STRUCTURE

NCSEA | CASE | SEI NOVEMBER 2019

CFS/Steel

INSIDE: Hudson Commons 38

Steel Stud Bearing Walls 8
Hot-Dip Galvanizing 20
Amherst New Science Center 30
 LeMessurier Calls on Tekla Structural
Designer for Complex Projects
Interoperability and Time Saving Tools
Tekla Structural Designer was developed specifically
to maximize collaboration with other project parties,
including technicians, fabricators and architects. Its
unique functionality enables engineers to integrate the
physical design model seamlessly with Tekla Structures
or Autodesk Revit, and to round-trip without compro-
mising vital design data.

“We’re able to import geometry from Revit, design in

Tekla Structural Designer and export that information
for import back into Revit. If an architect makes
geometry updates or changes a slab edge, we’ll send
those changes back into Tekla Structural Designer, re-
run the analysis and design, and push updated design
information back into Revit.”

Tekla Structural Design at Work:

The Hub on Causeway
Positioning a large scale mixed-use development next
to an active arena, a below grade parking garage, and
an interstate highway, and bridging it over two active
subway tunnels makes planning, phasing and
For over 55 years, “Tekla Structural Designer has streamlined our engineering paramount. Currently under construction,
LeMessurier has design process,” said Craig Blanchet, P.E., Vice Presi- The Hub on Causeway Project will be the final piece in
provided struc- dent of LeMessurier. “Because some of our engineers the puzzle that is the site of the original Boston Garden.
tural engineering are no longer doubling as software developers, it allows
services to architects, owners, contractors, developers us to focus their talents on leveraging the features of Despite being new to the software, LeMessurier
and artists. Led by the example of legendary structural the software to our advantage. Had we not chosen decided to use Tekla Structural Designer for significant
engineer and founder William LeMessurier, LeMessuri- to adopt Tekla Structural Designer, we would have portions of the project. “Relying on a new program for
er provides the expertise for some of the world’s most needed to bring on new staff to update and maintain such a big project was obviously a risk for us, but with
elegant and sophisticated designs while remaining our in-house software. So Tekla Structural Designer is the potential for time savings and other efficiencies, we
true to the enduring laws of science and engineering. not just saving us time on projects, it is also saving us jumped right in with Tekla Structural Designer. It forced
Known for pushing the envelope of the latest tech- overhead. us to get familiar the software very quickly.”
nologies and even inventing new ones, LeMessurier
engineers solutions responsive to their clients’ visions Efficient, Accurate Loading and Analysis “Tekla Structural Designer allowed us to design the
and reflective of their experience. Tekla Structural Designer automatically generates an bulk of Phase 1 in a single model,” said Barnes. The proj-
underlying and highly sophisticated analytical model ect incorporates both concrete flat slabs and compos-
An early adopter of technology to improve their de- from the physical model, allowing LeMessurier engi- ite concrete and steel floor framing. “Tekla Structural
signs and workflow, LeMessurier put its own talent to neers to focus more on design than on analytical model Designer has the ability to calculate effective widths
work in the eighties to develop a software solution that management. Regardless of a model’s size or com- based on the physical model which is a big time saver,”
did not exist commercially at the time. Their early appli- plexity, Tekla Structural Designer’s analytical engine said Barnes. “On this project, the integration with Revit,
cation adopted the concept of Building Information accurately computes forces and displacements for use along with the composite steel design features enabled
Modeling (BIM) long before it emerged decades later. in design and the assessment of building performance. us to work more efficiently. Adding the ability to do con-
crete design in the same model was a bonus because
While LeMessurier’s proprietary tool had evolved over we had both construction types in the same building.”
three decades into a powerhouse of capability, the
decision to evaluate commercial structural design “Tekla Structural Designer helped this project run more
tools was predicated on the looming effort required to “Tekla Structural Designer offers better efficiently, and in the end it was a positive experience,”
modernize its software to leverage emerging integration of multiple materials than said Blanchet.
platforms, support normalized data structure integra-
tion and keep up with code changes. we have seen in any other product.”

After a lengthy and thorough comparison of commer-

cial tools that would “fill the shoes” and stack up to the
company’s proprietary tool, LeMessurier chose Tekla “Tekla Structural Designer gives us multiple analysis
Structural Designer for its rich capabilities that ad- sets to pull from, which gives us lots of control. Most
dressed all of their workflow needs. According to Derek programs don’t have the capability to do FE and
Barnes, Associate at LeMessurier, ” Tekla Structural grillage chase-down. For the design of beam supported
Designer offered the most features and the best inte- concrete slabs, Tekla Structural Designer allows us to
gration of all the products we tested. They also offered separate the slab stiffness from the beam stiffness, so
us the ability to work closely with their development if we choose to we can design the beams without con-
group to ensure we were getting the most out of the sidering the influence of the slab. In the same model
software.” we can use a separate analysis set to review the floor
system with the beams and slab engaged,” said Barnes.
One Model for Structural Analysis & Design
From Schematic Design through Construction Docu- Barnes also shared similar benefits with concrete “Tekla Structural Designer provided the best fit
ments, Tekla Structural Designer allows LeMessurier column design. “Tekla Structural Designer does for our workflow compared to other commercially
engineers to work from one single model for structural grillage take-downs floor-by-floor, finds the reactions available software.”
analysis and design, improving efficiency, workflow, and applies them to the next floor. This allows us
and ultimately saving time. “Our engineers are working to view column results both for the 3-dimensional
more efficiently because they don’t need to switch effects of the structure as a whole and from the more
between multiple software packages for concrete and
steel design. Tekla Structural Designer offers better
traditional floor-by-floor load take-down point of view.
Doing both has always required significant manual Want to Evaluate
integration of multiple materials than we have seen in
any other product,” said Barnes.
intervention, but Tekla Structural Designer puts it all in
one place.” “We reduce the possibility for human error Tekla Structural Designer?
because with Tekla Structural Designer less user input
LeMessurier engineers use Tekla Structural is required,” said Barnes. “Tekla Structural Designer
Designer to create physical, information-rich models
that contain the intelligence they need to automate the
automatically computes many of the design parame-
ters, such as column unbraced lengths. The assump-
tekla.com/TryTekla
design of significant portions of their structures and tions made by the software are typically correct, but we
efficiently manage project changes. can easily review and override them when necessary.”

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4 STRUCTURE magazine
 Contents
Cover Feature

N OVEM BER 2019

38 HUDSON COMMONS
By Joseph Provenza, AIA, P.E., Jeffrey Smilow, P.E., Yujia Zhai, P.E.,
and Motaz Elfahal, Ph.D., P.E.

A fundamental question for every developer on sites with existing conditions

is to rebuild or reposition. For the acquisition of a drab eight-story commercial
building in Manhattan, developers decided that the 1960s-era cast-in-place
concrete building would receive seventeen floors of steel construction.

30 WHEN SCIENCE BECOMES 34 PERELMAN CENTER FOR POLITICAL

TRANSPARENT SCIENCE AND ECONOMICS
By Adam Blanchard, P.E., and Jeffrey Abramson, AIA By Allison Lukachik, P.E., S.E., and Amanda Gibney Weko

The glass façade of the Amherst College Commons is a structural The Ronald O. Perelman Center for Political Science and Economics
silicone glazed curtain wall system comprised of triple-glazed insulating involved renovation and reuse of a historic 1925-era building with
units. The curtain wall is hung in tension from a steel roof structure the construction of a new addition. Structural challenges involved a
cantilevered up to forty feet over the Commons below. Supporting the cantilevering steel feature stair, two steel transfer trusses, and the use
curtain wall is a paired steel plate assembly and steel tee profile. of concrete flat-plate floor framing.

Columns and Departments

7 Editorial The IRC – Does It Really Matter? 28 InSights Masonry Testing Technician Certification
Stephanie J. Young, P.E. By Nicholas R. Lang, P.E.

8 Structural Systems Steel Stud Bearing Walls 42 Structural Sustainability

By Connor Bruns, S.E., Eric J. Twomey, S.E., P.E., Terry McDonnell, S.E., P.E., Resilience: A Rallying Cry We Can Amplify
and Matthew Johnson, P.E. By Kate Stillwell

46 Structural Rehabilitation Adaptive Reuse of the Apex

12 Building Blocks SpeedCore
Hosiery Company Building – Part 1
By Jennifer Traut-Todaro, S.E.
By D. Matthew Stuart, P.E., S.E., P.Eng

16 Structural Quality Structural Masonry General Notes 50 Professional Issues

By Jefferson Asher, S.E., and John Chrysler, P.E. Upfront and In Need
By Dallas Erwin and Kate Peterson

20 Structural Practices Successful Detailing

for Hot-Dip Galvanizing In Every Issue
By Alana Hochstein 4 Advertiser Index
52 NCSEA News
24 Northridge – 25 Years Later 54 SEI Update
Nonductile Concrete Frames 56 CASE in Point
By Keith D. Palmer, Ph.D., S.E., P.E. 58 Resource Guide – Software Updates

Publication of any article, image, or advertisement in STRUCTURE® magazine does not constitute endorsement by NCSEA, CASE, SEI, the Publisher, or the Editorial Board. Authors, contributors, and advertisers retain sole responsibility for the content of their submissions.

N O V E M B E R 2 019 5
A Powerful Software Suite for Detailed
Analysis & Design of Reinforced Concrete Structures
 EDITORIAL
The IRC – Does It Really Matter?
By Stephanie J. Young, P.E.

L et’s face facts. It is unlikely that the majority of practicing struc-

tural engineers are familiar with the material contained within
the International Residential Code (IRC).
I expect you can tell that this issue is important to me. Our firm offers
engineering services to homeowners – something that is becoming more
and more rare. It has been an important part of our 35-year history, and
we intend to continue doing so. Contractors and homeowners contact
us for assistance with everything from investigating a failing founda-
Why would we? tion wall to the addition of another level on their house. Through our
When we provide a design for a new project, our guidance comes involvement in these projects, we have found it necessary to rely on
from the contents of the International Building Code (IBC) and related the IRC to better understand the basis for the original construction.
references. We must be familiar with this information, be comfortable Residential designs for new construction have also become more cre-
with the concepts, and understand how to ative, pushing the limits of what can easily
comply with these standards. Structures be addressed in a prescriptive code. Our
have become more complex. The Code firm is often asked to help interpret vari-
and the material standards must keep ous IRC sections that have been recently
pace with these changes. The result is a added to keep up with new materials and
collection of books that would rival my systems.
childhood encyclopedia set. While we have found that the major-
A request that structural engineers add ity of the information contained in the
the contents of the IRC to our repertoire design tables follow accepted engineering
would probably result in a groan or at practices and equations, several assump-
least a small chuckle. tions and limitations were involved in
Besides, the IRC itself indicates that its their development. Code language gener-
purpose is to allow for the construction of ally remains unchanged unless someone
one- and two-family dwellings without the need for an engineered design. speaks up. Maybe “the way things have been done for 20 years,” is
IRC Section R301.1 – “…The construction of buildings and structures just not good enough anymore. It is here where the value of structural
in accordance with the provisions of this code shall result in a system engineering knowledge comes into play.
that provides a complete load path that meets the requirements for the
transfer of loads from their point of origin through the load-resisting
elements to the foundation.”
What can we do?
It sounds like we are off the hook now, right? I have been the Chair of the NCSEA Code Advisory IRC Working
Well, maybe not. Our services could still be required. IRC language Group for the past two, 3-year code cycles, and I feel our work has
exists which allows for the engineered design of a specific element or been interesting and productive. Our group has been successful in
system, should that portion of the structure fall outside the criteria making code changes that corrected discrepancies and improved clarity.
for an IRC building. However, the remaining portion of the building It is not our vision to change the IRC to become an engineering
may continue to be constructed per the IRC prescriptive requirements. guideline like the IBC. Each of the codes has specific uses and targeted
IRC Section R301.1.3 – “…Where a building of otherwise conven- audiences and serve them well. Our goal is to ensure that the IRC is
tional construction contains structural elements exceeding the limits of not just a collection of empirical past practices but is based on proven
Section R301 or otherwise not conforming to this code, these elements engineering concepts. Codes are generally considered a summary of
shall be designed in accordance with accepted engineering practice.” minimum requirements and, as our engineering knowledge increases and
In this case, the engineer involved will likely provide the specific construction practices change, structural engineers should be monitor-
design based on the principles and practices they find most comfort- ing these documents to make sure they remain current and relevant.
able – namely those contained in the IBC. So, if you should encounter the IRC during your day-to-day activi-
There still seems to be no compelling reason to get involved with a ties, do not shy away. Take a bit of time to review and understand its
residential code, correct? contents. If you find a concerning issue, bring it to the attention of
our committee and we will do our best to address it through the code
revision process. If you have a bit more time and interest, volunteer
So then, why should we? to serve on your State or local Code Advisory Group, or join us at the
Our primary duty as engineers is to “hold paramount the safety, health, NCSEA level. All participation is welcome and appreciated.
and welfare of the public.” The public is not only a generic group of Structural engineers should do their best to elevate the
people, but includes our friends, families, and ourselves. Most people performance of all structures, including those we call home.■
spend nearly half of every 24 hours in their homes. This is more time
Stephanie J. Young is the President of Mattson Macdonald Young, Inc. in
than is spent in their offices, schools, churches, or shopping centers.
Minneapolis, MN. She is a member of the NCSEA BOD and Chair of
Yet we treat these facilities as somehow more worthy of our attention.
NCSEA Code Advisory IRC Working Group.
We, as engineers, have knowledge that can make life at home safer.

STRUCTURE magazine N O V E M B E R 2 019 7

 structural SYSTEMS
Steel Stud Bearing Walls
Multi-Unit Residential Construction
By Connor Bruns, S.E., Eric J. Twomey, S.E., P.E.,
Terry McDonnell, S.E., P.E., and Matthew Johnson, P.E.

P re-fabricated, structural cold-formed metal framing (CFMF) bear-

ing walls are a trending construction system and an economical
alternative to structural steel or reinforced concrete systems for mid-rise
construction. CFMF wall systems are particularly desirable for 6- to 12-story
multi-family apartments or condominiums, student housing, senior living,
and hotels. Vertically-aligned residential demising and partition walls Pre-fabricated, structural CFMF wall panels. Courtesy of Bear
Construction Co.
allow the CFMF to stack like timber-framed or concrete masonry unit
(CMU) bearing wall construction. However, CFMF wall buildings are less height restrictive than timber due to steel’s higher
strength and not as labor-intensive as CMU because of pre-fabrication. Additionally, CFMF systems integrate wall panels as
the structural system in what would typically be non-structural, stick-built partition walls.

The prevalence of CFMF wall panel systems comes with design and for floor levelness and are a heavier system resulting in increased load
construction challenges. Delegated design integration, trade coor- on the wall panels, podium, and foundations.
dination in a traditionally non-structural element, and fire-resistive Compared to steel deck options, CFMF floor joists may be appealing
detailing are among the challenges for this system. This article sum- because of their span capabilities without the use of shoring; however,
marizes the CFMF system layout process, design and specification a CFMF floor joist system is generally 6 to 12 inches deeper than a
options, and considerations that may be overlooked in initial plan- steel deck system leaving less room for MEP distribution, requiring
ning and pricing. lower ceilings or necessitating taller floor-to-floor heights. Additionally,
CFMF floor joist systems may require a fire-rated ceiling assembly
where steel deck systems can typically achieve an unprotected fire-
System Overview rating within the concrete. Steel deck options (shored or unshored)
CFMF systems are most efficient when the wall panels align, or “stack,” are appealing, given their simplicity in detailing and thin profile. For
from foundation to roof. Multi-unit residential construction often both decking and CFMF joist systems, if the span is parallel to a central
integrates programming space for retail, office, amenities, or park- corridor, a header is required to span from the end of the CFMF wall
ing typically at the lowest levels of the building. In these cases, the panel over the corridor. The header is a part of the structural load
CFMF bearing walls are constructed on a podium level, typically of path and may require a 1- or 2-hour fire rating.
structural steel or cast-in-place reinforced concrete. Both systems can The lateral load resisting system (LLRS) for a CFMF building can
be engineered to support discontinuous bearing walls and to provide be of a variety of structural systems. It may be beneficial to utilize
heightened fire rating separation that may be required between differ- the CFMF walls as the lateral system, relying on either sheeting or
ing occupancies. From the onset of a project, there should be a dialog CFMF steel straps. In this case, the transfer of overturning moments
between the design team and the owner to stack the walls, and ideally in the wall systems and transfer of the loads from the CFMF walls
the wall openings, to minimize transfers within the CFMF system. to the podium structure are important considerations; in the case of
CFMF bearing walls can be spaced between 10 and 32 feet apart depend- the former, the additional details may detract from the efficiency of
ing on the span capabilities of the floor construction. To span between the system. Alternatively, walls around the stairs and elevators are
the bearing walls, floor system options include cast-in-place concrete on an opportune location to introduce reinforced concrete shear walls,
unshored composite steel deck, cast-in-place concrete on shored long-span CMU shear walls, or steel braced frames for the LLRS. Regardless of
steel deck, or precast, prestressed hollow-core planks. Alternatively, floor the system chosen, the sequence of trades is a critical discussion to
construction may consist of concrete panels or steel deck supported on have with prospective contractors, whether they are involved early in
CFMF floor joists that span between the bearing walls. the project in a design-assist role or bidding the project.
Each floor system has advantages and disadvantages. For example,
concrete on unshored composite steel deck requires less labor associ-
ated with shoring than shored long-span steel deck; however, unshored
Design and Specification
steel deck is typically limited to a span length of about 15 feet, where Traditionally, CFMF wall panel construction has been governed by
long span deck can achieve up to 32 feet between structural walls. systems that were developed by fabricators and their Specialty Structural
Precast, prestressed hollow-core planks can achieve similar spans to Engineer (SSE). The SSE designs these systems, which are tuned to the
long-span steel deck; however, planks may require a structural topping preferred fabrication and installation techniques of the contractor. An

8 STRUCTURE magazine
alternate approach is for the Structural Engineer of Record (SER) on
the design team to design a custom stud framing system or to delegate
the design of a custom system to the contractor. The SER designing
the system is the least common approach and is not discussed here.
An appropriate delegated design, whether for a custom or proprietary
system, requires the design team to identify the location and extent of
the load-bearing CFMF walls on the drawings. The delegated design
of a building system describes a scenario where the SER provides a set
of design criteria for a contractor’s SSE to follow to design, fabricate,
and install the identified building system. In addition to identifying
the CFMF wall location and extent, it is essential that the design
team indicate other trades, both structural and non-structural, that
interface or are integral to the CFMF walls.
A crucial part of delegated design criteria is the communication of wall
and floor loading information to the contractor’s SSE. Floor load plans Unshored composite steel deck construction.
should be employed to show the magnitude and extent of superimposed
dead and live loads, particularly large or non-uniform loads and exterior construction. The matrix can be published with the construction docu-
wall loads. Specific details may also be required to indicate the location ments to define the design demarcation for each structural engineer. The
and magnitude of exterior wall loads or point loads, such as transfers, design team can rely on the matrix during submittal reviews to indicate
corridor transfer beams, and rooftop equipment. necessary coordination with other trades.
Exterior wall cladding is frequently a partial or complete delegated design. Regardless of the system – proprietary or custom – the SER should
The intersection of multiple delegated design components can result in develop a preliminary analysis of the typical CFMF wall components
poor coordination during construction. The design team needs to clearly both to establish the acceptability for the intended layout and to
document basis-of-design details for the integration of the various systems provide a basis of design for pre-construction budgeting and bidding.
as a basis for contractor bidding. In addition, a responsibility matrix is a This effort validates the approach, establishes design loads for the
useful tool to document the roles of the Architect of Record (AoR), SER, podium and foundations, helps the SER identify key layout options
the General Contractor (GC), the specialty subcontractors, the CFMF or constrictions, and indicates to the SER where special detailing,
fabricator/installer and their SSE, and the exterior wall fabricator/installer minimum size, or material gauge are required. This will help the SER
and their SSE during the submittal review process and the subsequent develop a more reliable delegated design.
continued on next page
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N O V E M B E R 2 019 9
 Top Track Details
Top tracks within a CFMF bearing wall function as a load-distribution
element where the floor system (e.g., the low flute of steel deck or
the flange of a CFMF joist) does not necessarily align with a vertical
stud. Wall panels are typically installed on top of each floor level, so
the top track should be designed/detailed to transfer the load of the
floor system and upper-level floors to the adjacent vertical stud. In
the authors’ experience, it is a false economy for the contractor to take
a cost savings by presuming the installers will align the floor system
with individual studs.
Construction Sequencing
Forethought into the coordination of trades during the vertical erec-
Shored long-span steel deck construction. tion sequence will drive construction efficiency. Traditional trades
such as masons, carpenters, ironworkers, concrete suppliers, and
concrete placement workers will need to be staged as each floor is
Design and Construction Considerations constructed, and they will need to be educated about the integration
of their systems with CFMF construction.
Podium Construction
Structural Studs vs. Partition Studs
Podium level construction should be designed to heightened deflection
criteria to account for the sensitivity of the gypsum wallboard (GWB) Historically, CFMF is not part of the primary structural building
clad CFMF bearing walls. Accumulated displacement can result in frame, typically serving as an exterior backup wall or a partition wall.
non-structural finish cracking if a podium level is not sufficiently While this is part of the intrigue and efficiency of the system, it can
stiff. Early programming should consider the increased depth of the create confusion on the construction site. Clearly documenting the
structure below the first floor of CFMF bearing walls. structural CFMF in both the structural and architectural drawings is
important. It is more important, however, to educate the contractor
Fire Ratings
and their subcontractor, early and often, that the structural CFMF
As the primary structural load carrying members, CFMF may be cannot be modified without review and analysis by the SSE for the
required to achieve up to a 2-hour fire rating. A 2-hour rating is achieved CFMF. Common field modifications include penetrations through
with a second layer of GWB on each side of the wall. This is an addi- studs for plumbing and electrical systems and temporary removal of
tional weight that needs to be considered in the design of the studs and studs for construction egress.
clearly indicated in the delegation language to the SSE. An additional
Exterior Cladding and Slab Edges
consideration for architects and contractors is the continuity of the
rating – it must continue around door jambs, electrical boxes, and similar The exterior edge of a CFMF bearing wall building can frequently be only
items integral with the structural CFMF wall. To the extent possible, the thin edge of a concrete slab on a steel deck. This creates a structural
the design team should coordinate all penetrations into a CFMF wall efficiency but can create heartache in the façade depending on the material
to occur within a non-structural portion of a CFMF structural wall to and attachment system. Determining the façade materials and attachment
simplify the fire rating details during construction. systems early when considering a CFMF structural system is critical – the
special details required of certain façade systems can quickly erode any
Future Flexibility
efficiencies in the structural CFMF. The AoR and SER should establish
While CFMF allows a typically non-structural partition wall to serve the basis of design details for the façade attachments and the requirements
as a primary structural element, it does not typically allow for future of both the structural and non-structural CFMF at façade attachments.
flexibility. While this may be acceptable for hotels and dormitories, it
may be less desirable in apartments and particularly condominiums
where owners may want the opportunity to modify their unit or
Summary
combine units in the future. A hedge against limiting future flexibil- CFMF bearing wall buildings are increasingly a cost-effective option
ity is to use a long-span floor system wherein either the exterior and in the low and mid-rise multi-unit residential market. As a new
corridor walls are the primary bearing walls, or only unit party walls approach to design and construction, there is a learning curve
are the primary bearing walls, or a combination thereof. for both designers and contractors. Understanding the
opportunities and the challenges of the system is key to a
Non-Stacked Walls
successful project.■
CFMF bearing walls are an efficient system for repetitive usage programs
such as residential. However, when atypical programs migrate into, under, All authors are with Simpson Gumpertz & Heger.
or above CFMF bearing walls, inefficiencies encumber the system. This Connor Bruns is a Consulting Engineer. (cjbruns@sgh.com)
typically takes the form of hot-rolled structural steel within the steel stud Eric Twomey is a Senior Consulting Engineer. (ejtwomey@sgh.com)
walls, an independent structural steel frame, or similar programs. This Terry McDonnell is a Principal. (trmcdonnell@sgh.com)
results in inefficiencies in the CFMF wall design and fabrication and
Matthew Johnson is a Principal. (mhjohnson@sgh.com)
increases the complexity of construction trade sequencing.

10 STRUCTURE magazine
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 building BLOCKS
SpeedCore
Lateral System Innovation for Today's
Construction Challenges
By Jennifer Traut-Todaro, S.E., LEED AP

T he millennial mindset is saving our profession. A

common question from young engineers – “Why
do we do things the way we do them?” – can be just as
off-putting to us as it is to the Baby Boomer down the
hall. The more experienced engineers often side with Gen-
Xer points of view and the played-out stories of rotary
phones, record players, and the lost art of hand-drafting. Figure 1. SpeedCore panel module in fabrication. Courtesy of Magnusson Klemencic Associates.
All we want to say is: “because we do.”
The thing is, the next generation is not challenging us. Instead, they Composite systems have been used for years, since pumpable con-
are challenging the history of how we do things – and it is a good crete was developed and became a structural material. Using the
thing they are because many of us have stopped asking, “WHY?” compressive strength and stiffness of concrete to enhance the strength
That question becomes more difficult to ignore when, for instance, a and ductility of steel is ideal, but prefabricated steel-plate composite
concrete contractor inevitably misplaces an embed to support a steel beam. (SC) wall panel development had gone the proprietary route and lost
The Request For Information in the designer’s inbox forces them to spend steam. The nuclear industry saw the safety and speed of the system’s
the time they do not have and money the owner did not plan to spend. construction and began to employ it in safety-related blast walls for
The Millennial mindset is saving our profession because when we nuclear facilities. They appreciated the additional robustness of the
get tired of asking why, millennials will jump in and do the asking for system’s properties, including radiation shielding and resistance to
us and, in turn, save the profession. Their answers to those questions extreme loading. The concept was able to gain popularity as an open-
can revolutionize everything we do. source option, designed by any engineer and built by any fabricator.

Innovate SpeedCore
Ron Klemencic, Chairman and CEO of Magnusson Klemencic Coupled Composite Plate Shear Wall – Concrete Filled (CCPSW-CF),
Associates (MKA), embraces that questioning mindset. At the 2019 or SpeedCore, is a non-proprietary, revolutionary method of composite
NCSEA Summit keynote, Klemencic stood on the stage and encour- structural-steel framing. The system consists of two steel plates that
aged the industry to ask “Why?” because he constantly asks the are held in position by cross-ties and a concrete core.
question himself – with revolutionary results. During construction, the steel faceplates with the steel cross-ties
Together with his MKA colleagues and AEC partners, he has brought provide stability under construction loading before the concrete infill
a previously existing idea forward in new packaging to the benefit is placed. In the case of Rainier Square Tower, permanent internal
of the project team, the owner, stability trusses were added for
and, ultimately, the industry. ease of transportation and erection
The Coupled Composite Plate (Figure 1). No additional concrete
Shear Wall – Concrete Filled wall formwork is built on-site. The
(CCPSW-CF) system is now pre-fabricated, panelized module
known as “SpeedCore.” serves as a permanent formwork
MKA had been exploring the for the concrete.
idea of a composite sandwich Ongoing research has shown
panel shear wall system for a taller that welded shear stud connec-
building application for several tors, in combination with fewer,
years before making a particularly more widely spaced cross-ties are
innovative proposal to Rainier effective in generating composite
Square Tower developer Wright action as well (Figure 2). After the
Runstad & Company: build the concrete infill has cured, it acts
first tall building project to use a compositely with the SpeedCore
composite core. Rainier Square components of plates, cross-ties,
Tower is a 58-story, mixed- and shear connectors. The steel
use, high-rise, currently under acts as both wall reinforcement
construction in the heart of and the primary resistance to ten-
downtown Seattle, Washington. Figure 2. SpeedCore construction detail. sion and shear demands on the

12 STRUCTURE magazine
lateral system. No additional wall reinforce- have shut down the Rainier Square Tower proj-
ment is placed on-site, greatly expediting wall ect without an innovative solution. Once the
construction. The concrete infill, working team behind Rainier Square Tower realized that
compositely with the steel faceplates, provides there would be an eight-week demobilization
overall flexural and shear stiffness to the struc- to complete only one level, and came to grips
ture because the confined concrete can resist with all the financial and logistical burdens
larger overturning compressive loads under related to that extended demobilization, they
lateral demands. took a serious look at SpeedCore.
In the SpeedCore erection schedule, there
is no need to advance the core ahead of the
surrounding steel frame to achieve simultane-
Rainier Square Tower
ous topping out, as in traditional cast-in-place Though MKA had been exploring the
concrete core construction. The construction SpeedCore concept for several years, no proj-
schedule is no longer subject to the time and ect team was ready to consider the progressive
on-site labor costs of placing formwork and SpeedCore module isometric. building idea and put pen to paper. A team
rebar. The module plates and cross-ties are pre- needed to silence that internal, nagging “why?”
fabricated off-site, leaving the steel erectors to do what they do best: to open their minds to an unconventional option. Once SpeedCore
build a kit of prefabricated parts. Embed site placement is a thing of was on the table for discussion, Rainier Square Tower’s general con-
the past, as they now arrive already affixed to the modules. The core tractor, Lease Crutcher Lewis, found the system promised substantial
is designed for advancing four stories above the surrounding structure savings. No rebar, no formwork, no curing lag, and no demobiliza-
in compliance with OSHA erection standards. tion for outrigger placement all meant a significant reduction to the
At first blush, SpeedCore undoubtedly builds faster. When building overall construction schedule.
with a concrete core, common practice means that concrete, with its To lend a sense of scale, the outriggers that provide additional
days-long curing period, sets the pace. The building schedule is at the lateral stiffness to the structure require 5,200-kip-capacity, buck-
mercy of advancing the concrete core. “Why?” The formed core must ling-restrained brace web members. This is one of the highest
be high enough that, once steel erection has begun, the erector does capacities of BRB elements manufactured. The outrigger loads
not have to demobilize and then remobilize. The concrete pour demo- are very high. For the original design, which used a conventional
bilization, due to high-capacity dissimilar material connections, would concrete core, MKA devised an embedded truss connection to

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N O V E M B E R 2 019 13
 and Cd = 5.5 – a system efficiency not
available during the design phase of
Rainier Square Tower. This confers a
significant reduction in loads applied
in analysis, taking better advantage
of the ductility and overstrength of
the SpeedCore system. Researchers
expect that more testing will facili-
tate additional optimization, such
as increased spacing between ties, a
reduction in overall wall thickness,
and a reduction in fire protection
requirements. Any of these improve-
ments would make the system even
more attractive.
There are currently four ongoing
SpeedCore research projects. As
more research is completed, design-
ers will be better able to evaluate
the system’s composite behavior and
Annotated two-story SpeedCore.
optimize the system even further.
Klemencic, Dr. Amit Varma (Purdue
transfer the load from the concrete core to the outriggers. In the University – Bowman Laboratory), and the American Institute of
SpeedCore version, the concrete is wrapped with the steel that is Steel Construction (AISC) are collaboratively producing a Design
typically cast inside the wall, allowing for more direct steel-to- Guide to aid engineers in this optimized design.
steel connections. Concrete’s weakness in tension no longer rules
the high-capacity connections, and the eight-week construction
shutdown is a thing of the past.
Combining “Why?” With Good Practice
Among the laundry list of challenges faced when designing and There is much promise in this system and engineers from all genera-
building, a significant reduction in a schedule is something to which tions must step out of their comfort zone to use it. The project team
we should be paying attention. The original cast-in-place concrete core of Rainier Square Tower took the time and resources to get it right
schedule estimated topping out 21 months after steel arrival on-site. for the benefit of the industry. Early and effective team communica-
During the planning phase, Lease Crutcher Lewis was confident that tion was key in setting up Rainier Square Tower for success. Early
the erection of the SpeedCore version of that same building would mock-ups to evaluate concrete mixes and pouring sequences ensured
take only 12 months. Switching to SpeedCore shaved nine months adequate consolidation and strength. Open-mindedness and realistic
off the construction estimate – almost 43% of the erection schedule goals drove the execution of mock-ups intended to evaluate planned
offsetting any additional construction costs associated with the system. efficiencies for shop and field fabrication methods.
The general contractor and the erector bettered their promise by an Once the tenants move into Rainier Square Tower and the next
additional two months, topping out the first week of August 2019. innovative building takes center stage, this building will be remem-
Long story short, Rainier Square Tower is the real-time market test bered for pushing the envelope. History will have been made. Asking
of the SpeedCore System. the question “Why?” might be tiring for those forced to find answers,
but it is what makes us better as designers – it is how we ultimately
build better. This is the pinnacle challenge of engineering. It is why
Research engineers studied problem-solving in school. It is why they have
Ongoing research is providing a better understanding of the SpeedCore so much fun in their careers. We should embrace the Millennial
system behavior under lateral loading and how the system’s materi- mindset and innovate.
als can be optimized. As an early innovator, MKA was not able to For more information about SpeedCore and its use in
take advantage of efficiencies they had theorized that are now being Rainier Square Tower, visit www.aisc.org/speedcore or
confirmed by research; the designers placed higher importance on a contact the Steel Solutions Center at solutions@aisc.org.■
streamlined review schedule and compliance with currently published
codes to design and permit the building. For the Rainier Square
Tower project, therefore, MKA designed the system conservatively, The online version of this article contains references.
using the same wall thickness used in the cast-in-place concrete core Please visit www.STRUCTUREmag.org.
option and a Seismic Response Modification Coefficient of R = 6.5.
MKA’s design method is documented and available for reference in
a joint Pankow Foundation-MKA design guide, Design Procedure for Jennifer Traut-Todaro is a Senior Advisor in the AISC Steel Solutions Center.
Dual-Plate Composite Shear Walls. This is the most current published Since SpeedCore broke onto the scene, Jennifer has been following the
design method and is conservative for today’s SpeedCore designs. development of SpeedCore research and the progression of the Rainier
The Federal Emergency Management Agency’s FEMA P695 Study Square Tower project. (trauttodaro@aisc.org)
preliminary findings assert that SpeedCore achieves R = 8, Ωr = 2.5,

14 STRUCTURE magazine
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 structural QUALITY
Structural Masonry General Notes
Specifying an Effective Quality Assurance Program
By Jefferson Asher, S.E., and John Chrysler, P.E., FTMS

T he quest for quality construction following a professional

design by the Structural Engineer is not a new concept. The
initial publishing of the 1927 Uniform Building Code (UBC), sub-
titled the material disciplines “Quality and Design,” acknowledged
the relationship between the design and implementation of a
construction project. Over the past 90 years, Quality Assurance,
the development of a program, and Quality Control, the imple-
mentation of that program, have evolved in such a manner that details can often cloud the ultimate intent.

The development of General Notes by Structural Engineers for spe- For several years, both sets of inspection tables matured. In 2009,
cific projects can be a challenging task, particularly regarding issues of the IBC contained a detailed list for two levels of masonry veri-
Quality Assurance and Quality Control. Conflicts can easily develop fication and inspection tasks in Tables 1704.3 and 1704.4. These
between the General Notes, the project Specifications, and the governing tables formed the basis for developing a Quality Assurance program
Building Code requirements. The development of Quality Assurance by listing the minimum Quality Control provisions required for
and Quality Control provisions contained in the 2016 version of TMS masonry construction. The two sets of tables ultimately disappeared
(The Masonry Society) 402/602, Building Code Requirements and in the 2012 IBC since they were redundant with the Verification
Specification for Masonry Structures, can help minimize these potential and Inspection Tables contained in TMS 402-11/ACI 530-11/ASCE
conflicts and provide design professionals with very helpful tools to 5-11, Building Code Requirements for Masonry Structures.
increase effective communication with all members of a project team.
Structural Notes
History Since the code has historically been lacking specific Quality Assurance
Although the concept of Quality and Design was introduced in 1927, and Quality Control provisions, Structural Engineers have been appro-
it was not until the 1943 edition of the UBC that a mechanism was priately listing material and construction requirements on structural
established to implement quality in masonry construction. Section drawings in the form of General Notes (as supplemented by the proj-
204 (b)2 stated that masonry must be continuously inspected by a ect Specifications). For the most part, Masonry General Notes have
“Registered Inspector” when the stresses exceeded 50 percent of the been a repetitive listing of material standards, such as ASTM C90 for
design stresses allowed by the masonry design chapter. Even though the Concrete Masonry Units, ASTM C270 for mortar, and ASTM C476
code required a “thoroughly qualified” registered inspector, there was for grout. In addition to listing the ASTM Standards, some of the
no direction on what constituted the qualifications or what to inspect. material properties contained in the Standards were also listed, such
The next code cycle (1946) required that the registered inspector be as the strength of the Concrete Masonry Unit, the strength and mix
qualified by the building official but, other than being qualified, the proportion of masonry mortar (which conflicts with the Standard),
registered inspector was given little direction on masonry inspection and the strength of grout.
for the next 30 years. Some progress was made in 1976 when the UBC
listed when to inspect masonry, such as during placement of masonry Table 1. Minimum quality assurance level.
units and reinforcement, before and during grouting operations, and
preparation of test specimens. Still, the code provided little guidance Designed in accordance Risk Category Risk Category
on the quality control aspects of masonry inspection. with I, II, or III IV
As the code transitioned into the International Building Code (IBC) • Allowable Stress Design
in 2000, inspection tables were introduced in the IBC and the ref- • Strength Design
erenced material standard, Building Code Requirements for Masonry Level 2 Level 3
• Prestressed Design
Structures (TMS 402/ACI 530/ASCE 5). Although similar, these • Strength Design of AAC
inspection tables contained inconsistencies, with the IBC taking a
senior position for inspection tasks. Even with the inconsistencies, • Veneer
this was a significant step forward in formulating consistent Quality • Glass Unit Masonry Level 1 Level 2
Control requirements. • Partition Walls

16 STRUCTURE magazine
 For example, there can easily be a con- Table 2. Verification.
flict in the way mortar is listed. That is, an Required for Quality Assurance(a)
inconsistent requirement for a specified MINIMUM VERIFICATION
mortar strength and a given proportion Level 1 Level 2 Level 3
mix. Numerous citations in the mortar Prior to construction, verification of compliance of
R R R
Standards explain why field-tested mortar is submittals.
not expected to meet the laboratory mortar Prior to construction, verification off ' and/or AAC,
strength as listed in ASTM C270. The pri- NR R R
except where specifically exempted by the Code.
mary reason is that the water-cement ratio of
mortar in the wall is significantly lower after During construction, verification of Slump flow
the masonry unit is laid when compared to and Visual Stability Index (VSI) when self- NR R R
the water-cement ratio in the test specimen. consolidating grout is delivered to the project site.
Another significant factor is that the aspect During construction, verification of f'm and f 'AAC
NR NR R
ratio of the mortar joint in a masonry wall for every 5,000 sq. ft. (465 sq. m).
provides a geometric configuration that is During construction, verification of proportions
considerably stronger than mortar in a test of materials as delivered to the project site for
specimen. NR NR R
premixed or preblended mortar, prestressing grout,
It is a customary practice for the Structural and grout other than self-consolidating grout.
Engineer to develop a master-set of General (a)
R=Required, NR=Not Required
Notes which are intended to be utilized on
every project. Of course, each construction
project is unique, and the specific circumstances and conditions which
TMS 402 Requirements
are associated with each project must be considered in the application IBC Section 1705.4 references TMS 402 for Quality Assurance
of the master-set of General Notes from project-to-project. Sometimes requirements. There are three levels of Quality Assurance in TMS
this does not occur, and General Notes which may be applicable to 402. Determination of the minimum quality assurance level is based
one project are left intact where different requirements may apply. on both the chosen design methodology and the Risk Category which
Further complicating this situation is the ever-changing nature of applies to the project at hand.
material standards and code requirements. This is all particularly true The Risk Category is as-defined in IBC Table 1604.5 and, to deter-
with respect to quality assurance and quality control issues. There is, mine the appropriate Quality Assurance level, the Risk Category is
however, a simple approach to circumvent the potential confusion. split into two groups. One group (Risk Categories I, II and III) covers
most buildings, and the other (Risk Category IV) encompasses critical
facilities expected to be operational after a disaster.
TMS 402/602 Requirements TMS 402 contains a simple table for determining the minimum
The Building Code Requirements and Specification for Masonry Structures Quality Assurance level applicable for a given project. A modified
document contains two standards, along with their commentaries: version of the table is shown in Table 1.
1) Building Code Requirements for Masonry Structures designated The most typical situation will include a structural design approach
as TMS 402 (formerly designated as TMS 402/ACI 530/ which utilizes either Allowable Stress Design or Strength Design,
ASCE 5);
2) Specification for Masonry
Structures designated as TMS 602
(formerly designated as TMS
602/ACI 530.1/ASCE 6).
These standards are produced by The
Masonry Society’s Committee TMS

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402/602. The Code covers design and
construction of masonry structures,
while the Specification is concerned
with minimum requirements for masonry
construction. The Code contains provi-
sions dealing with Quality Assurance in
masonry construction (along with many
other topics); the Specification covers
subjects such as Quality Assurance and
Quality Control in masonry construction.
In general, the Code is written as a
legal document, which is suitable for
adoption by the IBC; the Specification
is written as a master Specification which
is required by the Code and is meant to
be modified and referenced on a project-
specific basis.

N O V E M B E R 2 019 17
 implying that Quality Assurance Levels 2 and 3 will Table 3. Inspections.
be specified and utilized by the Structural Engineer. MINIMUM SPECIAL INSPECTION
Frequency(a)
General Notes Simplified Inspection Task
Level 1 Level 2 Level 3
Structural Engineers are rightfully concerned that 1. As masonry construction begins, verify that the
the project documents, including the General following are in compliance:
Notes, are complete, coordinated, and clearly com-
a. Proportions of site-prepared mortar NR P P
municate the design intent. Utilizing the Quality
Assurance tables provided in TMS 602 will not b. Grade and size of prestressing tendons and
NR P P
only provide a complete task list for Quality anchorages
Control but also will deliver a more consistent mes- c. Grade, type and size of reinforcement,
sage for the inspector and contractor to accurately connectors, anchor bolts, and prestressing NR P P
understand what is required to comply with the tendons and anchorages.
Quality Assurance plan set forth by the engineer. d. Prestressing technique NR P P
The 2016 version of TMS 602 went a step fur-
e. Properties of thin-bed mortar for AAC masonry NR C /P
(b) (c)
C
ther in combining all Quality Assurance levels
into a single table. Now, the Structural Engineer f. Sample panel construction NR P C
has the option of utilizing the Verification and
Inspection tables in their General Notes, in 2. Prior to grouting, verify that the following are in
their entirety, with a statement of which Quality compliance:
Assurance Level (1, 2 or 3) is required for com- a. Grout space NR P C
pliance (Tables 2 and 3). When field personnel b. Placement of prestressing tendons and
receive the same set of code-conforming require- NR P P
anchorages
ments for every job, understanding and applying
those requirements will improve dramatically. c. Placement of reinforcement, connectors, and
NR P C
The Structural Engineer may enhance the require- anchor bolts
ments, such as making some of the periodic tasks d. Proportions of site-prepared grout and
NR P P
continuous or scheduling how much periodic prestressing grout for bonded tendons
inspection is required.
3. Verify compliance of the following during
construction:
Conclusion
a. Materials and procedures with the approved
Masonry Verification and Inspection Tables are NR P P
submittals
contained in TMS 602, Specification for Masonry
b. Placement of masonry units and mortar joint
Structures, a consensus document maintained by a NR P P
construction
balanced committee of users (designers), producers
(industry representatives), and general interest stake- c. Size and location of structural members NR P P
holders (academia and others). Committee members d. Type, size, and location of anchors including
spend countless hours developing and maintain- other details of anchorage of masonry
NR P C
ing the document, including the Verification and to structural members, frames or other
Inspection Tables. Quality Assurance and Quality construction.
Control provisions are regularly evaluated and e. Welding of reinforcement NR C C
reevaluated to ensure that the provisions harmo-
f. Preparation, construction, and protection of
nize with current applicable Standards and other
masonry during cold weather (temperature
provisions and that they are published for reference NR P P
below 40°F (4.4°C)) or hot weather
into the model building code. By simply incor-
(temperature above 90°F (32.3°C))
porating these tables into the General Notes, the
Structural Engineer will have a level of confidence g. Application and measurement of prestressing
NR C C
that the intent of the Quality Assurance force
program will be understood and uni- h. Placement of grout and prestressing grout for
formly applied.■ NR C C
bonded tendons is in compliance
i. Placement of AAC masonry units and
NR C(b)/P(c) C
construction of thin-bed mortar joints
Jefferson Asher is a Managing Principal with KPFF
Consulting Engineers in Los Angeles, CA. Asher is
Past-President/Chairman of the Board of KPFF. 4. Observe preparation of grout specimens, mortar
NR P C
(jeff.asher@kpff.com) specimens, and/or prisms.
(a)
Frequency refers to the frequency of inspection, which may be continuous during the listed task or periodi-
John Chrysler is Executive Director of the Masonry
cally during the task listed, as defined in the table. NR = Nor Required, P = Periodic, C= Continuous
Institute of America and current Chair of TMS
402/602 Committee. (jc@masonryinstitute.org)
(b)
Required for the first 5,000 square feet (465 square meters) of AAC masonry.
(c)
Required after the first 5,000 square feet (465 square meters) of AAC masonry.

18 STRUCTURE magazine
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 structural PRACTICES
Successful Detailing for Hot-Dip Galvanizing
By Alana Hochstein

B atch hot-dip galvanizing (HDG) after

fabrication, a total immersion process in
molten zinc, has a more than a 150-year track
mechanical properties of the steel,
but certain practices will reduce or
eliminate concerns related to the
record of providing corrosion protection for galvanizing temperature (approxi-
steel in the harshest environments. Though mately 830 degrees F).
primarily known for corrosion resistance, For example, when steel is
hot-dip galvanizing following ASTM A123, immersed in the galvanizing kettle,
Specification for Zinc (Hot-Dip Galvanized) the change in temperature affects
Coatings on Iron and Steel Products, is increas- areas with increased residual stress
ingly specified for low initial cost, durability, from severe cold working. Parts
longevity, availability, versatility, sustainability, that are severely cold-worked
and aesthetics. To achieve these additional ben- reduce the steel’s ductility and
efits, there are several areas where structural increase the potential for cracking
engineers and detailers can work together to during hot-dip galvanizing due
ensure steel pieces are successfully fabricated to to strain-age embrittlement, the Holes for vertical and angled tube trusses.
achieve maximum galvanizing quality without effects of which are accelerated at
negatively impacting structural integrity. The the galvanizing temperature. Designers and
best practices specific to hot-dip galvanized steel detailers can incorporate best practices
Venting and Drainage Details
steel may be unfamiliar to structural engineers to reduce stresses induced during bending, As hot-dip galvanizing involves the immer-
and detailers experienced in other methods of hole-punching, rolling, and shearing prior to sion of steel in a series of process tanks, it is
corrosion protection, but an upfront effort to hot-dip galvanizing to avoid these concerns. critical to ensure the free flow of pretreat-
incorporate these details will pay dividends Recommendations for design best practices, ment solutions, air, and zinc so a smooth
in terms of reduced cost, quick turnaround, minimum bend diameters, and thermal treat- and uniform coating is achieved. Improper
and optimal quality. This article summarizes ments to relieve internal stresses are found venting and drainage details can result
key topics which have the most significant within ASTM A143, Standard Practice for in poor appearance, bare spots, excessive
impact on the quality of hot-dip galvanizing for Safeguarding Against Embrittlement of Hot- build-up of zinc, blowouts, or danger to
general corrosion protection, Architecturally Dip Galvanized Structural Steel Products and plant personnel. To optimize galvanizing
Exposed Structural Steel (AESS), painting or Procedure for Detecting Embrittlement. quality, ASTM A385, Standard Practice
powder coating after hot-dip galvanizing, and The galvanizing process temperature can also for Providing High-Quality Zinc Coatings
fireproofing. impact susceptible fabrications, which may (Hot-Dip), provides preferred venting and
distort as a result of relieving stresses induced drainage details for poles, handrails, trusses,
Impact of HDG Process during steel production and fabrication. ASTM tanks, gusset plates, stiffeners, end-plates,
A384, Standard Practice for Safeguarding and bracings. Most venting and drainage
Temperature Against Warpage and Distortion During Hot- details do not impact structural integrity or
Studies investigating common structural steel Dip Galvanizing of Steel Assemblies, identifies design function, but occasionally the pre-
grades confirm the hot-dip galvanizing pro- factors and types of fabrications prone to dis- ferred hole sizes and placements may not be
cess produces no significant changes in the tortion as they experience different thermal suitable for assemblies or trusses when large
expansion and contraction stresses in holes are placed on the sides of load-bearing
addition to uneven heating and cooling members. Alternative hole details provided
during angled immersion into the gal- in ASTM A385, in addition to direct com-
vanizing kettle. Specifically, light gauge munication with the detailer and galvanizer,
material (20 gage to < ¼ inch) welded can lead to a suitable substitute, sometimes
or riveted to plate, bars, or angles tend to at the expense of aesthetic quality or overall
distort, as do a-symmetrical pieces and corrosion protection.
fabrications containing different material
thickness that heat and cool at different
rates. Distortion is primarily mitigated
Material Size and Shape
through design measures found within Galvanizing kettle dimensions limit the size of
ASTM A384 to avoid high internal articles which can be fully coated. The average
stresses and steel details for temporary galvanizing bath is 40 feet long, but 55- to
or permanent bracing to provide stability 60-foot-long baths are common. Oversized
during the inevitable thermal expansion articles are designed in modules, galvanized
Overlapping surfaces. and contraction cycles. separately, and joined by bolting or welding.

20 STRUCTURE magazine
 For slip critical connections, galva-
nized steel offers a lower slip coefficient
than bare or mild steel and therefore
decreased slip resistance. Clearance holes
sized 1⁄8 inch larger than the nominal
bolt diameter are acceptable for slip-
critical connections and accommodate
galvanized bolts without hole clearing.
Standard clearance holes are already sized
1
⁄8 inch larger for bolts sized 1 inch or
greater, but this same increase results
in an oversized hole for bolts sized less
than 1 inch in diameter. When oversized

Say
Rust bleeding. holes are used, a further reduction in
slip capacity due to the reduction in the
Alternatively, progressive dipping (dipping connection area ensures slip does not occur.

Hello
each end of the article sequentially) is used As the design slip resistance is reduced 15%
to fully coat articles nearly double the bath for connections using oversized through-
dimensions. However, progressive dipping holes, this leads to additional bolts in the
results in uneven heating and cooling of the connection design.

to the
material since only a portion of the article is Where painted or black steel faying surfaces
immersed in molten zinc while the other is are required to achieve a higher slip resistance,
exposed to cooler air. This results in differ- the HDG coating is ground off in the field,

New
ent expansion rates for the upper and lower or a masking material is applied before galva-
part of the component, which may distort nizing to prevent coating formation. Suitable

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the article. Distortion can be mitigated by masking materials include acid-resistant or
confirming lifting arrangements with the high-temperature paints, tapes, greases, and

3N
galvanizer, requesting increased venting thread compounds. Alternatively, zinc-silicate
and drainage to allow quick immersion and paints are applied to galvanized faying sur-
withdrawal from the galvanizing kettle, and faces to increase the slip coefficient without
designing for thermal expansion conditions. coating removal.

Deck.
Specifically, welds and constrained or framed
portions of an assembly must be designed to
handle the increased stresses from thermal
Welded Connections
expansion at the galvanizing temperature. It is possible to weld after HDG using
all conventional welding techniques with
Bolted Structural
Connections
no impact on overall structural design.
However, when assemblies are welded prior It's still
N deck.
to HDG, there are recommended design
The components of a bolted connection, and detailing practices to ensure adequate
including nuts, bolts, or studs, are sent to the corrosion protection and structural integrity.
galvanizer when disassembled. Components
with male threads are galvanized normally,
It is best practice to avoid designs such as
back-to-back channels with narrow gaps It's just
wider.
while nuts and holes are provided an increased between overlapping surfaces to be welded.
thread size after galvanizing to accommodate Less viscous pretreatment solutions enter
the increased bolt thread diameter that results the gap between these surfaces, but zinc
after application of a thick galvanized coating. cannot enter gaps less than 3⁄32-inch-wide.
Oversizing guidelines for interior threads for Trapped fluids or air will superheat to gas at See the advantages
galvanizing are detailed in Table 5 of ASTM the galvanizing temperature and may result of Vulcraft 3N Deck
A563, Specification for Carbon and Alloy in destructive pressures or weld blowouts. vulcraft.com/decks
Steel Nuts. Otherwise, the internal surfaces uncoated
For bearing type connections, the pres- by zinc will eventually weep out of the gap
ence of a hot-dip galvanized coating on with unsightly rust stains. Such areas need
the contact surfaces is not detrimental to to be sealed using silicone caulking or an
performance and does not affect design epoxy sealer to prevent weepage.
strength. Section J3.2 of the AISC Manual Where overlapping surfaces are unavoid-
of Steel Construction: Load and Resistance able, the engineer should be involved and
Factor Design (LRFD manual) states over- informed regarding the options for steel
sized holes are not to be used in bearing type details listed in ASTM A385 to avoid these V U LC R A F T G R O U P
connections, but hole interior may require concerns. When the gap between overlap-
unblocking or cleaning after galvanizing to ping surfaces is less than 3⁄32-inch-wide, fully
ensure bolt placement. seal-weld these areas to prevent the access

N O V E M B E R 2 019 21
 for AESS and will significantly improve identically to a duplex system. When apply-
the appearance of assemblies containing ing spray-applied fire-resistive materials
multiple steel chemistries and steels of (SFRMs) over galvanizing, pre-application
chemical compositions outside the rec- of mechanically fastened galvanized metal
ommended ranges for galvanizing listed lath or the use of a bonding agent may be
in ASTM A385. Next, galvanized AESS required. Further recommendations will vary
projects will also benefit from additional by fireproofing manufacturer.
attention to cut edges. Flame, plasma,
or laser cutting increases hardness and Resources for Hot-Dip
alters the diffusion properties near the
cut edge, either making it difficult to Galvanizing Detailing
Galvanizing roughness.
develop a coating or resulting in a thick Most design best practices and steel details
of cleaning fluids. However, seal-welding can coating which is prone to delamination. For necessary for successful galvanizing are read-
inadvertently affect the structural behavior all AESS categories, grind thermally cut edges ily available and easily adopted from the
of the welded components, and the use of up to 1⁄16 inch. Finally, direct communication supporting ASTM specifications referenced
seal-welding requires a variance to comply with the engineer and galvanizer to determine throughout this article.
with AWS D1.1, Structural Welding Code – placement, quantity, and size of vent and To better navigate and visualize the informa-
Steel. Alternatively, the detailer may specify drain holes in relation to the lifting orienta- tion contained in these galvanizing standards,
stitch welding when the gap is at least 3⁄32 inch. tion can help maximize aesthetics without the American Galvanizers Association (AGA)
Although this method provides full corrosion impacting structural integrity. publication Design of Products to be Hot-dip
protection to the interior area, the engineer Galvanized After Fabrication and the National
should be consulted to confirm if a full seam Institute of Steel Detailing (NISD) publica-
weld is required for structural purposes.
Duplex Systems tion, Hot-Dip Galvanizing: What We Need To
A duplex system involves applying paint or Know, contain a wealth of practical examples
Architecturally Exposed powder coating over the hot-dip galvanized and standard reference tables. Additionally,
coating to achieve desired aesthetics or increased the AGA publication Recommended Details
Structural Steel longevity. ASTM D6386, Preparation of Zinc for Hot-dip Galvanized Structures provides
Because the initial appearance of HDG is (Hot-Dip Galvanized) Coated Iron and Steel working drawings with details for commonly
challenging to predict, a uniform finish can Product and Hardware Surfaces for Painting, galvanized components.
be difficult to achieve without significant provides the standard practices to prepare gal-
cost to remedy common surface conditions vanized surfaces for painting. Instructions are
unsuitable for AESS members (roughness, included for smoothing, cleaning, and profil-
Early Communication
runs, excess zinc). To facilitate communica- ing the surface based on the identified initial A basic understanding of the hot-dip galva-
tion and minimize the cost, Section 10 of the surface condition. Meanwhile, ASTM D7803, nizing process, recommended steel details,
AISC Code of Standard Practice describes a Preparation of Zinc (Hot-Dip Galvanized) and a review of the above considerations are
categorical approach for AESS members based Coated Iron and Steel Product and Hardware key to producing a high-quality galvanized
on viewing distance and type/function of the Surfaces for Powder Coating, contains similar coating. However, do not underestimate
structure. To achieve the elevated standards practices for powder coating. These specifica- the value of discussing elevated standards
of each AESS category, the AESS Custom tions list surface conditions, such as zinc runs or unique elements of a project with the gal-
category can be used to incorporate additional and rough coatings, which present challenges vanizer and fabricator directly. Establishing
details to maximize aesthetic quality. when the part is duplexed. open lines of communication early on in
For example, abrasive blast cleaning of the the design process is the best way to maxi-
steel before galvanizing, per SSPC SP 6/ mize aesthetics for the corrosion protection
NACE No. 3, is not required for standard
Passive Fireproofing of AESS members, duplex systems, passive
structural steel but is the specified minimum Some passive fireproofing materials require fireproofing, and more. These conversations
additional prepa- are worth the extra time upfront to alleviate
ration to achieve potential future headaches and will result
a particular bond in the fabrication of structures that will
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• Expert Advice such as what live loads to use, how to estimate damping, recommended materials (IFRMs) contains references. Please visit
acceleration or velocity limits, and more. often require a www.STRUCTUREmag.org.
• Makes use of the new complex analysis procedures for sensitive equipment and specific primer to
occupancies in DG11 2nd Ed. easy.
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should be prepared

22 STRUCTURE magazine
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 NORTHRIDGE 25 YEARS LATER
Nonductile Concrete Frames
By Keith D. Palmer, Ph.D., S.E., P.E.

T he Northridge earthquake struck the

greater Los Angeles area during the
early morning hours of January 17, 1994.
the use of a lower
“K” factor, which
can be thought of as
The earthquake was responsible for approxi- proportional to the
mately 60 deaths, more than 9,000 injuries, inverse of the “R”
and an estimated $20 billion in damages. factor in ASCE 7.
Significant ground shaking occurred over a Meanwhile,
wide area and exceeded design code values researchers and
in many locations. Numerically, most of practitioners were
the damage was to wood-frame residences, beginning to under-
but upwards of 200 concrete buildings were stand the advantages
red-tagged. The Northridge earthquake of ductile behavior
was the first big test of pre-1980 concrete and began testing
buildings and post-1980 buildings designed and quantifying Figure 1. Kaiser Permanente. Source: NISEE-PEER, University of California, Berkeley.
using updated code provisions following the ways to provide
1971 San Fernando earthquake. The 1971 ductility in concrete structures. In 1961, 5) Weak columns – strong beams.
San Fernando earthquake exposed the defi- Blume, Newmark, and Corning published 6) Slab-column punching shear.
ciencies of the building codes in place at the Reinforced Concrete Buildings for Earthquake 7) Plan or vertical irregularities resulting
time, particularly related to concrete. The Motions. The book provided design methods in torsion or soft or weak stories.
collapses of the Olive View Medical Center and detailing principles for ensuring duc-
and the Veterans Administration Hospital tile behavior such as maximum allowable Damage to Concrete
that occurred as a result of the San Fernando steel percentages, providing closely-spaced
earthquake are famous examples of the haz- closed ties in columns and beams, and pro- Frame Buildings
ards posed by “nonductile” concrete (NDC) viding continuous top and bottom steel for The damage caused to pre-1980 concrete
buildings. Several of these NDC buildings stress reversals. Unfortunately, the concept buildings by the Northridge earthquake was
collapsed or were severely damaged during of a ductile moment-resisting frame did significant but not a surprise. In general, pre-
the Northridge earthquake as well, includ- not find its way into codes until the 1967 1980 shear wall buildings met life safety and
ing the Kaiser Permanente Office Building Uniform Building Code (UBC). However, collapse prevention performance objectives.
(Figure 1) and Saint John’s Hospital. This ductile frames were required only for build- The Sherman Oaks Towers was a 12-story
article discusses building code provisions ings greater than 160 feet in height. These building designed to the 1964 Los Angeles
for concrete structures, the performance of provisions required smaller tie and stirrup City Code. The structure comprised flat-slab
non-ductile concrete frame structures in the spacing along the lengths of moment frame floors and relatively symmetric concrete shear
Northridge earthquake, associated changes columns and beams, respectively, and special walls, on the perimeter and surrounding the
made to the building code after, and retrofit transverse joint reinforcement. elevator core. Damage consisted primarily of
ordinances being considered today for existing The San Fernando earthquake provided shear wall boundary element failure due to
non-ductile concrete buildings. the impetus to update code requirements to the lack of closely-spaced confinement rein-
ensure the ductile behavior of concrete struc- forcement. The building was yellow-tagged
tures, and the 1976 UBC is considered to be but was repaired relatively quickly with epoxy
Seismic Code Background the first code to provide seismic resistance of injection of the cracks and installation of steel
Seismic building codes are continually concrete buildings similar to current code. straps at the location of the wall boundary
evolving based on new information gained Given the lag in construction year relative to element failures.
through research and observation of building design year, the benchmark that most engi- Pre-1980 frame buildings typically fared
performance during earthquakes. The great neers use for determining if a building is likely worse than their shear wall counterparts.
1906 earthquake prompted the City of San NDC is 1980. The Holiday Inn in Van Nuys was a seven-
Francisco to include earthquake design load The most common types of deficiencies in story concrete frame structure built in 1966.
requirements for buildings. In July 1959, the NDC buildings include: The frames consisted of exterior column-
SEAOC Seismology Committee published the 1) Beam and column stirrups and ties spandrels and interior flat slabs. Minor
first edition of the Blue Book, officially titled spaced relatively far apart, caus- structural damage occurred during the San
Recommended Lateral Force Requirements. This ing shear failures and lack of core Fernando earthquake but was repaired using
“code” was the first to formalize the relation- confinement. epoxy injection and patches. The building
ship between earthquake demands, building 2) Use of 90-degree bends on closed stir- was red-tagged following the Northridge
period, and the ductility of the lateral-force- rups instead of 135-degree hooks. event and required temporary shoring for
resisting system. Preference was given to 3) Lack of joint shear reinforcement. fear of collapse. The major damage mainly
moment-resisting space frames for lateral 4) Inadequate lap splices and locating consisted of column shear failure below
resistance relative to bearing walls through them in regions of high flexural stress. the fifth floor due to lack of ties (Figure 2),

24 STRUCTURE magazine
 proper confinement for the longitudinal
reinforcement, causing loss of gravity-
load carrying capacity. Similarly, damage
occurred in frame buildings that utilized
flat slab floor construction that was not
designed to accommodate large displace-
ments and the shear demands imposed
on them at the column. A flat slab build-
ing with perimeter moment frames in the
Sherman Oaks area is one such building.
Slab damage, including spalling and con-
crete crushing, was observed on the top
and underside at the columns around the

It's
outline of the drop panel. This building
was red-tagged by the city. A few similar
failures were also observed in residential

N deck
concrete podium garages with wood struc-
tures above.
Several buildings and parking garages saw
partial or total collapse, including the Kaiser

that's
Permanente Office Building (Figure 1)
in Northridge and two garages at the
Figure 2. Holiday Inn, Van Nuys. Source: NISEE- Northridge Fashion Center. The Kaiser

eight
PEER, University of California, Berkeley. collapse was attributed to inadequate con-
finement in the columns and shotcrete

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which led to significant spalling and buck- shear walls inadequately attached to the
ling of the longitudinal reinforcement. The frame. The Northridge parking garages

inches
building was later retrofitted with concrete were relatively new structures (circa 1988)
shear walls. but were constructed of precast double
Champaign Tower is a 15-story concrete and inverted tees. Failure was attributed
building in Santa Monica and experienced to large diaphragm movements causing

wider.
extensive perimeter column damage due to the failure of gravity columns that lacked
deep parapets on the balconies. This “short- proper confinement. Additionally, large
column” behavior results from high shear out-of-plane displacements of the perim-
demands that the columns attract due to eter frames occurred causing the precast
their high stiffness. The coupling beams in beams to unseat. Collector failures were
the shear walls in the orthogonal direction also observed in the topping slabs of precast The extra eight
also experienced significant shear damage. decks in the vicinity of shear walls.
Surprisingly, the damaged columns were still A large percentage of rigid-wall-flexible-
inches gives you:
able to maintain gravity load resistance. diaphragm buildings were also damaged. • Faster installation
Saint John’s Hospital is another building These buildings typically comprise walls cast
located in Santa Monica and consisted of on the ground and tilted up into position • Fewer bundles to lift
several buildings, built between 1942 and with a panelized wood roof system. Several
• Fewer sheets to spread
1966, that were damaged. The Main Wing roof collapses occurred due to failures of the
and the South Wing were yellow-tagged, connection between the tilt-up panels and • Fewer side-laps to connect
and the North Wing was red-tagged and diaphragm (See the past STRUCTURE arti-
demolished. The North Wing lateral system cle, April 2019, by Lawson and McCormick). • Compatibility with Hilti,
comprised perimeter punched concrete walls. In general, post-1980 and retrofitted Pneutek, Simpson
Significant shear cracking occurred in the buildings performed as intended with a and other fasteners
piers and spandrels at the second floor. There few exceptions. A retail facility in Topanga
was less wall at this level than the one above, Plaza, constructed in the early 1960s, was See the advantages
resulting in a likely weak-story. Additionally, retrofitted in 1989 through the addition of of Vulcraft 3N Deck
the piers were relatively short in many loca- shotcrete walls. These walls were attached vulcraft.com/decks
tions creating a “short-column” condition. to the existing walls with dowels designed
Taller piers at the second floor did not experi- to transfer the calculated seismic forces. The
ence shear cracking. new walls were designed to resist seismic
Much of the column damage and collapses load in tandem with the existing walls. More
were caused because the columns, designed damage occurred in the new walls; the exist-
V U LC R A F T G R OU P
for gravity loads only, were not detailed to ing walls exhibited sliding shear failures at
accommodate the displacements they would the base, transferring most of the load to the
undergo during an earthquake. As a result, new walls. Additionally, many of the cracks
shear failures occurred and did not provide in the new walls occurred along horizontal

N O V E M B E R 2 019 25
 planes likely caused by shrinkage of the shot-
crete walls and the lack of gravity loads on
Current Status
the new walls. Modern standards such as ASCE 7,
Minimum Design Loads for Buildings and
Recommendations Following Other Structures, and ACI 318, Building Code
Requirements for Structural Concrete, con-
the Earthquake tain the requirements for concrete structures
Following the earthquake, significant field designed for seismic resistance. The infor-
investigations and studies were performed by mation provided represents a vast body of
structural engineers that resulted in several rec- knowledge gained through observations after
ommendations to improve the performance of earthquakes and theoretical and experimental
concrete buildings. The UBC was published research performed at universities. However,
every three years, but interim changes are often there are still thousands of pre-1980 NDC

The
produced; several changes directly related to the buildings in high seismic regions in the
failures observed in Northridge were imple- U.S. and abroad. The California Seismic
mented in the 1996 UBC Supplement. Safety Commission estimates that there are

N deck
1) The strength-reduction factor for 40,000 in California. The SEAONC Existing
reinforcement used for diaphragm Buildings Committee, in cooperation with
chords and collectors in topping slabs EpiCenter, recently completed an inventory
over precast concrete members was based on all Sanborn maps for the City of

for all
reduced to 0.6 from 0.7. San Francisco. The inventory resulted in an
2) Minimum thickness of topping slabs estimate of 3,400 pre-1980 concrete build-
placed over precast floor and roof ings, verifying the estimate calculated by

your
elements was increased from 2.5 to 3 the Concrete Coalition. The risk of these
inches or 6 times the diameter of the buildings has not been accurately quanti-
ADVERTISEMENT–For Advertiser Information, visit STRUCTUREmag.org

largest slab reinforcing bar. fied and is difficult given the variability of
3) Spacing limits and transverse rein- building configurations, system types, and a

design
forcement requirements were added frequent lack of drawings. Methodologies to
for chord and collector reinforcement determine the risk of these buildings include
at splices and anchorage zones. ASCE 41, Seismic Evaluation and Retrofit of

needs.
4) The coupling beam definition was Existing Buildings, Tiers 1, 2, and 3, and the
expanded to include all beams con- recently developed methodology for ranking
necting walls regardless of the span/ buildings in an inventory, ATC 78, Seismic
depth ratio. Additionally, a maximum Evaluation of Older Concrete Frame, Frame-
shear strength limit of 10√f'c was Wall, and Bearing Wall Buildings for Collapse
added, along with the requirement Potential. Several Southern California cities
Available in the that longitudinal bars be enclosed have recently adopted ordinances that require
following versions: with transverse reinforcement.
5) Allowance of smaller amounts of
owners to assess the collapse potential of their
older concrete buildings and retrofit these if
(FM and UL Listed)
reinforcement in compression mem- the assessment deems this necessary. These
3NL-32 Nestable side-lap bers with a cross-section larger than cities include the City of Los Angeles, West
required for loading was removed for Hollywood, and Santa Monica. San Francisco
3NI-32 Interlocking side-lap members in Seismic Zones 3 and 4. is currently deciding what to do about the
® 6) Stricter requirements were imple- NDC building stock in the city. The knowl-
3PLN-32 PunchLok II system
mented for frame members not part edge to design and retrofit concrete buildings
of the lateral system. Tie spacings safely currently exists. Hopefully, the cur-
See the advantages were reduced for members with rent stock of NDC buildings will be
of Vulcraft 3N Deck induced moments and shears (from able to be economically retrofitted
vulcraft.com/decks 3(Rw/8) times the displacements) that before the next big one hits.■
do not exceed the design moment
and shear strength of the member. The online version of this article
Additionally, when the axial load in contains references. Please visit
those members exceed 30% of the www.STRUCTUREmag.org.
design axial strength, they must be
reinforced according to the provisions
for lateral frame members. Keith Palmer is a Senior Project Manager in
The City of Los Angeles/SEAOSC Task Force the San Francisco office of Simpson Gumpertz
also recommended that DBS survey and iden- & Heger. He is the current Chair of the
V U LC R A F T G ROUP Existing Buildings Committee of the Structural
tify all concrete structures constructed before
Engineers Association of Northern California
1976 and develop a mandatory retrofit ordi-
and the Co-Chair of the Nonductile Concrete
nance. As discussed below, the ordinance has
Subcommittee. (kdpalmer@sgh.com)
finally been implemented albeit 25 years later.

26 STRUCTURE magazine
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 INSIGHTS
Masonry Testing Technician
Certification
Raising the Bar for Testing and Quality Assurance
By Nicholas R. Lang, P.E.

I t is a familiar situation for anyone who has

been involved in a masonry construction
project. Things have progressed through
quality assurance programs.
The level for a given proj-
ect is defined in TMS 402,
design, bidding, and contracting, and are in Building Code Requirements
the construction phase. One day, as part of the for Masonry Structures. The
specified quality assurance program, a testing level required depends on Nicholas Lang of the National Concrete Masonry Association discusses
laboratory technician visits the job, samples the type of design used as critical measurement verifications for concrete masonry units.
materials, and takes them away for testing. well as the Risk Category
Sometime later, usually after 28 days, the for the building. For example, an empirically
dreaded call is made – the materials are not designed structure in Risk Category I, II, or
Scope of Certification Program
compliant. The project shuts down, meetings III requires Level 1 Quality Assurance; while There are two separate certification
ensue, and further evaluation, usually costly a building designed using Strength Design in programs; the Masonry Field Testing
destructive testing, is performed. Finally, Risk Category IV requires Level 3 Quality Technician (MFTT) program, which is
additional testing shows satisfactory results Assurance. designed to evaluate technicians sampling
and the project resumes. However, this process The requirements for each level of quality and testing in the field, and the Masonry
has caused significant lost time and testing. assurance are found in TMS 602, Specification Laboratory Testing Technician (MLTT)
There can be ways to reduce the frequency for Masonry Structures. The quality assurance program, which evaluates the knowledge
of situations such as the ones described program can contain a variety of things, from of technicians who test materials in the
above. A crucial part of improving quality a review of project submittals to inspection laboratory. The test methods for determining
assurance and testing of masonry products requirements to testing. All levels of masonry properties of masonry materials have been
is ensuring the person performing the testing quality assurance require at least some mate- developed through ASTM International.
is knowledgeable about masonry testing rial testing. Ensuring that this testing is done Many of these standards have both field
procedures and is qualified to perform this properly, in accordance with ASTM standards and laboratory components. Because of
testing. A relatively new tool for qualifying and test methods, is of utmost importance. this, there is overlap in the actual methods
technicians is the American Concrete Depending on the applicable level of quality between the two certification programs,
Institute (ACI) Masonry Testing Technician assurance, tasks related to material evaluation although there is no overlap of actual
Certification Program. Developed by ACI in and testing from TMS 602, Table 3, include: content. The MFTT program evaluates
conjunction with industry experts from The • Prior to construction, verify f´m and knowledge based on the field components
Masonry Society (TMS), Portland Cement f´AAC unless exempted by code of the relative standards, and the MLTT
Association (PCA), and the National Concrete • During construction, verify grout program evaluates knowledge based on the
Masonry Association (NCMA), this program slump flow and Visual Stability Index lab components.
provides a mechanism for testing technicians for self-consolidating grout The ASTM standards used by the programs are:
to be certified to test masonry products. • During construction, verify f´m and f´AAC • ASTM C67 – Sampling and Testing
for every 5,000 square feet of masonry Brick and Structural Clay Tile
• During construction, verify propor- (MFTT only)
Why is Testing Necessary? tions of materials for preblended • ASTM C90 – Loadbearing Concrete
It is important to understand why testing of mortar, prestressing grout, and grout Masonry Units (MLTT only)
masonry products is necessary. Testing can be other than self-consolidating grout • ASTM C140/C140M – Sampling and
performed for a wide variety of reasons, such Unfortunately, testing of masonry materials Testing Concrete Masonry Units and
as product development, quality control on is sometimes performed incorrectly. This is Related Units (MFTT & MLTT)
behalf of the manufacturer, and compliance primarily due to a lack of familiarity with specific • ASTM C270 – Mortar for Unit
with various specifications. When performed testing requirements for masonry. Testing labs, Masonry (MLTT only)
on a specific project, testing is usually part of in general, are usually more familiar with testing • ASTM C780 – Preconstruction and
the overall quality assurance program. for poured concrete, and there are some specific Construction Evaluation of Mortars
As defined by masonry building codes, differences in how masonry materials are tested. for Plain and Reinforced Unit Masonry
quality assurance is “The administrative and The goal of the ACI Masonry Testing Technician (MFTT & MLTT)
procedural requirements established by the Program is to evaluate the knowledge of • ASTM C1019 – Sampling and Testing
contract documents to assure that constructed individuals on the proper testing requirements Grout (MFTT & MLTT)
masonry is in compliance with the contract and to recognize those that demonstrate • ASTM C1314 – Compressive Strength
documents.” There are three levels of masonry command of that knowledge. of Masonry Prisms (MFTT & MLTT)

28 STRUCTURE magazine
 • ASTM C1552 – Capping Concrete that the questions can be varied for different In many aspects, they are still in the early
Masonry Units, Related Units and exam offerings. For the performance exam, stages of adoption.
Masonry Prisms for Compression checklists were developed that detail each There is an identified need for a certification
Testing (MLTT only) step in the test method. These checklists are program based on experiences with improper
These test methods were selected because used by examiners during the test to ensure testing and job site problems, as discussed
they are the ones most commonly performed that examinees cover all needed steps and earlier in this article. This primarily relates
on masonry materials. For some methods, demonstrate proficiency in each one. to field technicians; however, there must also
such as ASTM C140/C140M, only part Following development, ACI staff audited all be an incentive for laboratory personnel to
of the standard is covered. ASTM C140/ materials to ensure that questions were fair and participate. The 2016 version of TMS 602
C140M contains test methods for a wide instructions were satisfactory. From there, two has a new requirement to “Utilize qualified
variety of concrete masonry products, pilot programs were held in different locations in laboratory technicians to perform required
including concrete masonry units (CMU), the U.S. The feedback from the pilot programs laboratory tests.” The commentary to the
concrete pavers, segmental retaining wall was used to refine details of the program further. Specification lists the ACI certification
units, and more. The certification, however, Finally, after several years of development, the programs, or equivalent, as a way to
only covers testing of CMU. CMU is the program was approved by ACI’s Committees demonstrate that a technician is qualified.
product tested most frequently by a wide and offered to all interested parties. With this version of TMS 602 adopted into
variety of laboratories and is required for the 2018 International Building Code, demand
quality assurance on many projects by TMS for these programs will increase.
602. Future certification programs may cover
Becoming Certified Additionally, efforts are underway to
more products and methods. In order to become certified, an interested require certified technicians with ASTM
individual needs to find a sponsoring group standards. ASTM C1093, Practice for
Developing a that is offering the program. TMS is a National Accreditation of Testing Agencies for
Sponsoring Group and provides the program Masonry, contains requirements for quality
Certification Program in locations around the U.S. on request. In control and assurance for labs. The standard
Once the need for a program is identified, addition, local chapters of ACI (located in the currently includes minimum experience
the first step in development is to create a U.S. and throughout the world) may offer the requirements for lab personnel but does
committee. The committee that was tasked program. The best way to find a class is to not contain certification requirements. The
with developing this program was ACI 601-C, check with TMS (www.masonrysociety.org) committee charged with maintaining this
chaired by Chris Robinson, Executive Director or a local ACI chapter. standard is actively evaluating changes to
of the Construction Materials Engineering Many sponsoring groups offer optional require certifications for testing personnel,
Council in Orlando, FL. This committee education/review sessions to help prepare and it is expected that this will be included
was populated with subject matter experts, examinees, but there are no required in C1093 in the future.
industry representatives, and testing laboratory prerequisites for the certifications. The written
personnel. Many interested industry groups examination is broken into sections for each
were represented and provided support for test method. A minimum score of 70% overall
Summary
developing the program: The Masonry Society is required, as well as at least 60% on any There is a demonstrated need for accu-
(TMS), the National Concrete Masonry individual section, to pass the written exam. rate testing of masonry materials used in
Association (NCMA), the Portland Cement For the performance examination, each test is construction. Proper equipment must be
Association (PCA), and others. TMS took performed. The examinee must achieve 100% used, the correct procedures followed, and
a leadership role in the development and on each of the methods, and they have two technicians must be knowledgeable and com-
subsequent promotion of the program. trials for each method. petent to assure this. The ACI Masonry Field
Once the overall scope of the programs, Both the written and performance Testing Technician and Masonry Laboratory
including the test methods listed above, was component must be completed in order to Testing Technician programs were developed
developed, the next step was to create a Job achieve certification. This ensures that the to address knowledge and competency. These
Task Analysis (JTA). The JTA is a step-by- technician not only has sufficient knowledge programs evaluate the knowledge and skill
step walkthrough of a test method, describing but has the ability to perform necessary testing of technicians on common masonry tests
in detail the knowledge and skills needed for skills. The certification is good for 5 years, at in both the laboratory and the field. Use of
a technician to perform the work required which time the individual must re-certify by qualified, certified individuals will raise the
by the test. Since both certification programs passing the exams again. level of testing quality for masonry materials
include both a written examination and a The program is maintained regularly by ACI and reduce instances of improper testing. All
performance examination, the JTA identifies Committee C670, which is comprised much designers and specifiers are encour-
the information that a technician needs to like the original development committee, aged to require certified testing
know (and is evaluated in the written exam) with representation by testing labs, industry technicians for masonry testing.■
and those items that are a skill (and is evaluated groups, subject matter experts, and other
in the performance exam). Once the committee interested parties.
approves this JTA, exam development begins. Nicholas R. Lang is the Vice President of Business
The committee developed a sizable bank of
written examination questions that covered
Increasing Demand Development for the National Concrete Masonry
Association. He is an active member of ASTM
the breadth of knowledge for each test For a certification program to be successful, International, The Masonry Society, and the
method. The question bank was 2-3 times there must be demand. These certification American Concrete Institute. (nlang@ncma.org)
as large as needed for any given exam so programs have been available since late 2014.

N O V E M B E R 2 019 29
 When Science
Becomes
Amherst College’s New Science Center enlivens the sciences on campus by allowing the community
to see the work being done. Courtesy of Chuck Choi Architectural Photography.
Transparent
By Adam Blanchard, P.E., and
Jeffrey Abramson, AIA, LEED AP

“One of the defining features of this building is transparency. It really demystifies the sciences.”
– Amherst College Operations
T he New Science Center (NSC) at Amherst College anchors In realizing the architectural vision of the Commons space, a struc-
the eastern edge of the bucolic hilltop campus in Amherst, tural scheme needed to be developed that would accommodate the
Massachusetts. From overall organization to the finest detail, the multi-story, column-free space and would evince the feel of a living
design of the NSC achieves transparency and interaction at every room serving the whole campus. By hanging the glass wall from the
level. The surrounding landscape seamlessly meets the transparent roof structure, the wall mullions would be in tension and thus would
glass façade of the Commons, blurring the edges of the central living require smaller sections to resist the design loads. Concurrent with
room and creating a gathering space that feels like an extension of being in tension due to the self-weight of the steel and glass, the
the outdoors. paired plate mullions of the glass wall are subjected to bending forces
The glass façade of the Commons is a structural silicone glazed from the wind and seismic loads acting laterally. The tensile stress in
curtain wall system comprised of triple-glazed insulating units and the paired plate mullions is analogous to a pre-tension of the steel
an automated shading system which controls the glare and the overall so that, in bending conditions, the mullions remain in permanent
lighting levels. The curtain wall is hung in tension from a steel roof net tension, thus negating the need for stability bracing. The base
structure cantilevered up to forty feet over the Commons below. of the mullions are connected through two vertically slotted holes
The structure supporting the curtain wall is comprised of a paired which allows the bending moment to be resisted – and resolved to
steel plate assembly and steel tee profile which acts as the vertical lateral loads into the concrete slabs – while preventing any vertical
mullion for the system. The approach to hang the system and design load forcing the mullions into compression.
the structure as an assemblage of components, rather than a larger The structural system of the NSC is cast-in-place concrete throughout.
single member, resulted in maximized transparency and transmis- However, the roof structure spanning over the Commons necessitated
sion of daylight as it filters through the members to the interior. a steel frame to sustain the weight of the glass wall concurrently with
The building’s primary unifying feature is the distinctive roof which cantilevering over the column-free Commons space. The columns
covers the multi-story, glass-enclosed Commons and provides a quiet supporting the glass wall are nearly 40 feet removed from the curtain
visual datum for the undulat-
ing Pelham Hills beyond. The
roof performs many functions
simultaneously: it provides both
natural and artificial light, its
photovoltaic panels generate
electricity, and its shape and
materials afford acoustic con-
trol, all while radiantly heating
and cooling the Commons.
The steel roof structure, con-
cealed within curvilinear glass
fiber reinforced gypsum ceil-
ing panels, is cantilevered
from the exposed concrete
structure of the lab wings over
the Commons, which in turn Structural detail at the base of the glass wall and the connection View of the erected steel paired plate mullions and two-bolt
suspends the glass curtain wall. to the concrete wall and slab. connection at the base of the glass wall.

30 STRUCTURE magazine
wall, supporting a load of nearly 10,000 to the varying stiffness of the cantilevers
pounds per mullion in addition to the and the changing magnitude of the applied
dead, snow, wind, and seismic loads. loads, leveling nuts were implemented
The roof frame is comprised of cantile- where the cantilevers were anchored to
vered beams reaching from 32 to 40 feet columns.
from its nearest support, each aligned These nuts, sometimes as far as 40 feet
with a curtain wall mullion assembly. from the glass wall, allowed very fine
Near the free end of each cantilever is adjustments to the initial position of the
the connection of the curtain wall; each steel cantilevers by turning the nuts as
connection sustains up to 10 kips. The much or as little as needed; a small adjust-
cantilevers are anchored to the tops of ment in the leveling nut would result in
the concrete columns in the lab wing. a comparatively large repositioning of the
Due to the programmatic need for an cantilever at the glass wall position. In this
open lab environment, it was infeasible manner, each cantilever was able to be set
to have columns spaced at the same at a pre-determined elevation before load-
5-foot-3-inch-rhythm of the roof steel. ing the steel with the glass wall. Selecting
As a result, some of the cantilever steel the proper elevation to set the cantilevers
roof beams were supported not directly required that the Glass Design-Assist
by columns, but by girders spanning Structural detail of the cantilevered W36 roof beams with Contractor supply LeMessurier with the
leveling nuts for adjustability throughout glass installation.
between the columns. loads of the glass wall at each cantilever so
Each roof cantilever supported variable that deflections could be predicted. This
amounts of load, adding a layer of complexity to the already-variable would allow the steel to deflect to the datum elevation once the entire
support conditions: cantilevers supporting the full 70-foot-high glass glass wall was suspended from the roof steel. The predictions of steel
are flanked on each side – where the pavilions interact with the glass deflection were determined via a full finite element model of the roof
wall – by cantilevers supporting loads for only a 10-foot height of frame, applying the glass reactions supplied by Novum Structures.
glass. In some instances, beams supporting the highest and lowest
loads were immediately next to one another; the relative stiffness of
adjacent cantilevers needed to be tailored on a one-by-one basis so
In-Situ Deflection Control
that two conditions were met: Once the glass wall was hung from the roof steel, achieving a consistent
1) The top of the glass wall (i.e., the underside of steel) was at a horizontal datum across the roof, the differential deflection of adjacent
constant elevation after the glass was hung. cantilevers needed to be controlled to limit the stress placed on the
2) No two adjacent cantilevers deflected more than ¼ inch dif- caulking between adjacent panes of glass. By querying the roof finite
ferentially under transient loads (wind, seismic, snow). element model, the section properties of the cantilevers were adjusted
Because cantilevers holding different loads and consisting of varying to result in deflection characteristics across the entire roof such that
supports will lead to different structural deflections, the two condi- no two adjacent cantilevers deflected by more than ¼ inch due to
tions noted above needed to address both the initial position of the transient loads. This effort involved increasing the section properties
cantilevers and the in-situ movements of the cantilevers. of some W36s (including custom built-up shapes) to decreasing the
section properties of others and allow normalization of deflections
at each cantilever location.
Initial Position – Adjustability Installation followed the careful planning and selection of the cantile-
W36 steel beams were selected for the cantilevers in all instances to vers. Barr & Barr engaged Structures Derek to erect the structural steel
maintain consistent steel elevations, both at the top of steel for a flat with the task of setting each piece at its designated elevation. To achieve
roof and the bottom of steel for a consistent datum for the glass wall; this, surveys were conducted frequently to provide continuous feedback
this also allowed for a consistent length of glass wall mullions. Due about the position of the steel defining the datum at the top of the

Structural detail at the head of the glass wall and the connection to the cantilever beams. View of the erected roof framing and curtain wall connection plates at the top of the wall.

N O V E M B E R 2 019 31
 “This is the biggest transformation of the Amherst campus since its founding. It says that we
care deeply about science, and it says the same thing about community, about our commit-
ment to sustainability, about our commitment to beauty.” – AMHERST COLLEGE, PRESIDENT
glass. As the cantilevers Science Center. The resulting glass wall, with its perfectly vertical
were tied together with and horizontal datum lines, underscored the close coordination
secondary framing and of the entire project team. It was through this meticulous craft in
roof deck, final adjust- design and construction that the driving forces of layered
ments were made to the transparency and academic connectivity were achieved,
steel before installing the and the campus fundamentally transformed for the future.■
glass. Once the roof was
in its final connected Adam Blanchard is a Principal at LeMessurier and teaches at The Boston
condition, adjustments at Architectural College. (ablanchard@lemessurier.com)
Schematic section at Commons showing the one leveling nut resulted Jeffrey Abramson is a Senior Associate at Payette. (jabramson@payette.com)
framing geometry of the column (right), in a proportional effect
glass wall (left) and the roof cantilevers (top).
on cantilevers on either
side of the adjusted location. Surveys were conducted periodically Project Team
through the installation of glass, and corresponding adjustments were Owner: Amherst College, Amherst, MA
made at the leveling nuts so that, at the end of glass installation, the Structural Engineer: LeMessurier, Boston, MA
steel had come into alignment across the entire length of the roof, Architect: Payette, Boston, MA
precisely as planned. Construction Manager: Barr & Barr, New York, NY
Faced with an aging science center unable to accommodate today’s Structural Steel Contractor: Structures Derek, Sainte-Marie,
technologies, equipment, and pedagogies, Amherst sought a new, Quebec, Canada
forward-looking building that would create an open learning envi- Glass Design-Assist Consultant: Studio NYL, Boulder, CO
ronment for the entire campus community for the next 100 years. Glass Design-Assist Contractor: Novum Structures
By creating a Commons space that was welcoming, the desired Menomonee Falls, WI
effect of a living room had been brought to life inside the New

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 T he University of Pennsylvania’s
Ronald O. Perelman Center for
Political Science and Economics (PCPSE)
serves as a unified facility dedicated
to global social science teaching and
learning. It opened to students for the
2018-2019 academic year.
The $77.6 million project involved
a 54,440-square-foot renovation
and reuse of the historic 1925 West
Philadelphia Title and Trust Co. Building
with the construction of a new 56,700-
square-foot addition. Kuwabara Payne
McKenna Blumberg Architects (KPMB)
of Canada designed the project to inte-
grate old and new. The combined facility
contains a 120-seat auditorium, class-
rooms, collaboration areas, computing
rooms, and faculty offices. LEED Silver
Certification remains pending.
Exterior dusk view from 36th and Walnut Streets of the PCPSE on the
University of Pennsylvania campus. Courtesy of Adrien Williams.

PERELMAN CENTER
FOR POLITICAL SCIENCE AND ECONOMICS
BY ALLISON LUKACHIK, P.E., S.E., C.D.T.,
An Unlikely Pair: Steel Trusses and Flat-Plate AND AMANDA GIBNEY WEKO

Keast & Hood structural engineers of Philadelphia, PA, provided exterior, the two separate campaigns revealed themselves through
structural design for the project, led by Principal Constantine G. slight changes in the structural framing and discovery of a sizable
Doukakis, P.E., and Associate Allison Lukachik, P.E., S.E., C.D.T. rubble stone wall roughly separating the basement into halves.
Structural challenges involved a 30-foot-tall cantilevering steel Keast & Hood dug into historical archives maintained by the
feature stair, two 19-foot-tall steel transfer trusses to enable a column- Athenaeum of Philadelphia and old city maps to confirm that not
free lower-level auditorium, and the use of concrete flat-plate floor only was the building constructed as two sequential campaigns
framing to compensate for low floor-to-floor heights in the West separated by only two years, but it was designed under two different
Philadelphia Title and Trust building. To further complicate efforts, architects. Unfortunately, drawings did not exist for either project,
no structural drawings existed for the original building, which fea- and the concrete-encased steel limited the engineers’ ability to gain
tured two variations on an existing concrete-encased steel structure. much information via visual survey. The team used 3-D laser scan
Through the use of 3-D structural analysis and team collaboration, information and probes to understand the structure and identify
the engineering solution applied structural gymnastics and more beam sizes. Engineers found that the system changed slightly within
than a little creativity. the addition. Lightweight steel joist framing discovered at the second
level revealed the original two-story banking space was infilled at
some point. Although in good condition, the steel’s age meant it had
Existing Conditions limited strength. In locations where new usage necessitated higher
Shortly after the West Philadelphia Title and Trust building opened loads, the concrete had to be removed, steel reinforcements added,
in 1925, an addition was built. Mostly indistinguishable from the and fire-resistive materials spray-applied to restore the fire rating.

34 STRUCTURE magazine
 Programmatic and Pragmatic
Acknowledging the limits of the existing building structure to
minimize the need for structural reinforcements, the team placed
high-occupancy spaces in the new building and lower-occupancy
rooms in the original bank building. The new forum was one
exception to this approach where reinforcement of the 1927 fram-
ing was introduced.
The design removed a significant portion of the second-floor infill
to recreate the original grandeur of the ground floor. Inserted within
the void previously occupied by an old stair and elevator towers, a
new feature stair provides access to the auditorium. A basement loca-
tion for the auditorium worked best with circulation and ability to
accommodate the depth of sloped seating. However, functionality as
an auditorium necessitated a column-free room.
Keast & Hood considered post-tensioned concrete because it
Construction progress elevation view of long span, steel story truss with steel
could achieve both the large span and meet the low floor-to-floor hangers down to the first-floor structure.
height of the existing building, but recognized its future limita-
tions. Making penetrations in post-tensioned concrete requires
care to avoid cutting tendons, which carry a large amount of
Transfer Trusses
force. While controlled de-tensioning is both possible and safe In the new portion of the building, two 19-foot-tall, 53-foot-long
when done correctly, the process can be costly. Since the ceiling steel transfer trusses support four floors above and one floor below
of the auditorium forms the floor plate of a large classroom and to enable the column-free basement auditorium. Steel beams frame
circulation above, engineers wanted to avoid potential limitations between the trusses at the building’s first, second, and third levels,
and ensure the University of Pennsylvania had the flexibility for infilling the floor slab within the surrounding flat-plate concrete
future changes without requiring costly structural interventions. slab structure. The second floor frames into the bottom chords; the
When viewed in the context of the space and architectural objec- third floor frames into the top chords; and from the bottom, six steel
tives, steel proved the best solution. hangers support the first floor. The concrete columns for floors four

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N O V E M B E R 2 019 35
 through seven and the roof bear on the stair assembly. Three-quarters to one-
trusses, which become integral to the inch-thick steel plates serve double duty
structure of the entire building. These as the stair’s stringers and guard rails,
two trusses in effect support all levels giving the stair a sleek, industrial look.
of the building either through direct These plates also provide the stiffness
framing, hangers, or via columns that necessary to cantilever out 30 feet from
post up from their top chords. the floor slab, with minimal deflection
experienced under code-prescribed
loading conditions, and to ensure vibra-
Flat-Plate Concrete tion issues common to feature stairs
Most of the former bank building fea- did not manifest. Challenges included
tured floor-to-floor heights of 12 feet. determining depths into which struc-
To accommodate comfortable ceil- tural elements could be concealed,
ing heights of nine to ten feet, and to understanding how the stair would
avoid awkward shifts of floor heights be fabricated, and evaluating whether
between the old and new parts of the the handrail would be used structur-
building, Keast & Hood turned to flat- ally. Analysis efforts determined that
plate concrete. The solution kept the the handrails were not required for the
structure to the 12-foot ceiling height 3-D feature stair analysis model rendering created in Ram Elements. stability or reinforcement of the deep
and accommodated mechanical, elec- plate stringers, allowing their architec-
trical, and plumbing runs in the ceiling space without infringing tural expression to remain independent. The architecturally exposed
on the already tight space. At column locations where punching steel also required careful detailing of welds for a clean visual appear-
shear was a concern, stud rails within the depth of the concrete slab ance. Engineers used RAM Elements to perform analyses. The team
were utilized instead of large column drop caps, keeping the ceiling engaged stair engineer Providence Engineering Corporation of
cavity open. Traditional steel with concrete slabs on deck would have Lancaster, Pa., who verified design and constructability, matching
compromised too much head height, reducing the ceiling heights the structural team’s numbers exactly.
to uncomfortably low positions.
Creativity and Collaboration
Systems Integration The challenging constraints of the existing building inherited by the
The use of steel to span the auditorium and support the addition, design team encouraged a high degree of creativity and
and the use of flat-plate concrete in the addition, required detailing collaboration that resulted in an impressive facility for the
to ensure compatibility of the different systems. Integration with University of Pennsylvania.■
the existing concrete-encased steel structure further complicated the
process. Engineers used several programs within the Bentley RAM Allison Lukachik is an Associate with Keast & Hood in Philadelphia, PA.
software suite to perform analysis and eliminate potential conflicts. She served as Project Manager for the Perelman Center for Political
Particular effort was made to manage and coordinate construction, Science and Economics structural engineering scope of work.
including phasing between the two structural building trades. (alukachik@keasthood.com)
Amanda Gibney Weko is Principal of AGW Communications in
Signature Stair Haddonfield, N.J. Trained as an architect, she writes for and about the built
environment and is a longtime collaborator with Keast & Hood.
A 30-foot-tall cantilevering steel feature stair connects three levels of (amanda.weko@agwdesigncommunications.com)
the conjoined building. The signature staircase provides primary access
to the basement auditorium. Here, structural gymnastics compensated
for horizontal thrust at the floor levels and provided support for the Project Team
cantilevered condition. Owner: University of Pennsylvania, Philadelphia, PA
The stair cantilevers down from each floor like a sideways Z, attaches Structural Engineer: Keast & Hood, Philadelphia, PA
to the next floor, and cantilevers again. Sections of the slabs were Architecture: Kuwabara Payne McKenna Blumberg Architects,
removed and replaced with horizontal steel trusses that tie into the Toronto, Ontario, Canada
existing columns to deal with horizontal thrust at floor levels. These Construction Management: Hunter Roberts Construction
are capped with steel plates for support and aesthetic uniformity with Group, Philadelphia, PA
the steel stair. The design eases the massive horizontal forces developed Concrete Subcontractor: Healy Long & Jevin, Wilmington, DE
as a result of the cantilevered condition while not overstressing the Environmental Design and Energy Analysis: Atelier Ten,
slabs. A substantial concrete mass footing anchors the stair at the base New York, NY
and ensures horizontal loads do not transfer to the adjacent rubble MEP/Fire Protection Engineering and LEED Administration:
stone basement wall of the existing building. AHA Consulting, Inc., Lexington, MA
The stair solution required much collaboration between architects Stair Fabricator: Crescent Iron Works, Philadelphia, PA
and structural engineers. Hidden horizontal tube steel trusses were Steel Fabricator and Erector: Steel Suppliers Erectors, Inc.,
incorporated at each landing to prevent twisting. Hidden steel tubes Wilmington, DE
beneath the stair treads provide added support and stiffness to the

36 STRUCTURE magazine
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 T
Hudson
o Rebuild or Reposition? That is the fundamental question
every developer must address when acquiring a site with exist-
ing conditions. In New York City, a place known for its ephemeral
urban fabric and innovative high-rise buildings, large developments

Commons
often lean towards a tabula rasa (clean slate) for ease of construction
and maximum flexibility. Cove Property Group, however, had other
plans when they acquired a drab eight-story commercial building on
34th St and 9th Ave in Manhattan. The existing 1960s-era cast-in-place
concrete building would receive seventeen additional floors, encom-
INNOVATIVE APPROACHES passing 300,000 square feet, in the form of a sleek steel office tower.
TO VERTICAL EXPANSION When its transformation is complete, Hudson Commons will be a
26-floor, LEED Platinum Class A property accommodating 700,000
By Joseph Provenza, AIA, P.E., LEED AP BD+C, square feet of rentable office space (Figure 1).
Jeffrey Smilow, P.E., F.ASCE, Yujia Zhai, P.E.,
Hudson Commons was conceived by Cove Property Group. The
and Motaz Elfahal, Ph.D., P.E.
architect of this visionary renovation and addition is Kohn Pederson Fox
Associates (KPF) with WSP serving as the engineer of record. Mueser
Rutledge Consulting Engineers (MRCE) served as the geotechnical
consultant. The construction manager is Pavarini McGovern (PMG).

Project Description
Hudson Commons is situated in the heart of Manhattan’s west side.
The area has seen an expansive transformation in recent years, most
notably the 14-acre Hudson Yards megaproject just to the west. As a
direct neighbor of Penn Station to the east, the site is tightly woven
into the urban fabric and infrastructure of New York City.
The existing 423,000 square-foot cast-in-place structure was initially
designed as a warehouse and built in 1962. The structure is comprised
of two-way concrete slabs on a 24- by 28-foot grid with drop panels,
“mushroom” capitals, and a masonry core providing lateral stability. The
low, massive building is representative of the period. Early site investiga-
tions showed that the robust structure was in excellent structural shape.
The expressive vertical expansion adds 17 floors of steel construction
rising to 421 feet, bringing the total rentable area to 700,000 square
feet. The addition takes the form of a sleek modern office tower inher-
ently amalgamated to the bold Hudson Yards development rising just
beyond. The subtle renovation of the original building, which includes
a new wrap-around brick façade and curtain wall, keeps the project
grounded in the context of the neighborhood and its 1960s roots.
Accomplishing the vision developed by Cove and KPF required
WSP to face several unique challenges which would inspire highly
innovative structural solutions. Indeed, the existing cast-in-place
columns and footings required sizeable retrofits for the gravity loads
of the new tower above, and the existing roof slab required extensive
retrofitting to accommodate a landscaped park. The most invasive
feature, however, was the addition of a new reinforced concrete core
linking existing and new construction to provide lateral stability for
the new taller building. Adding to the complexity of the upgrades was
the combined decision of the client and the CM team for a shoring-
free demolition of a 125- by 25-foot area throughout the existing
building to accommodate the new core.

Foundation System
The geotechnical composition of the site and the existing foundation
elements presented an interesting engineering challenge. While the
existing structure was bearing on the good-quality substrate typical
of Midtown Manhattan, the bearing capacity ranged from 20 to 40
ton/ft2, and there was a steep drop off through the site. Furthermore,
the constraints of working within the confines of an existing structure
were immediately evident, particularly for the use of deep foundation
elements and the associated equipment.
Figure 1. Before and after renderings of the Hudson Commons renovation.
38 STRUCTURE
Courtesy of Neoscape, Inc. 2017.
magazine
 The new reinforced concrete core is sup- concrete. Also, WSP provided 3-D laser scan-
ported by a new 48- to 72-inch-thick mat ning services for the entire structure which
foundation bearing directly on sound bedrock yielded an accurate representation of as-built
(Figure 2). With the core walls in-line with column dimensions and locations, the latter
existing columns, consideration of existing being critical to tie in the tower grid above. To
column foundations added another layer of minimize any potential compatibility effects,
complexity. While some column foundations concrete strength for the retrofitting jackets
were narrow piers reaching the bedrock, a matched the one determined through the
few columns were supported by larger pile coring campaign (approximately 5,000 psi).
caps. The latter were treated as breaks in the Continuity of reinforcement was critical
mat foundation with cold joints only. The to maintaining a consistent load path. GPR
small footprint of the new core translated scanning was performed at each column
to large overturning moments which were allowing WSP to map and coordinate loca-
addressed by providing 45 600-kip anchors tions for holes to be drilled for reinforcement
socketed 45 feet into rock. MRCE speci- to pass through the existing slabs. Large diam-
fied 450-ton micropiles socketed 15 feet into eter (#14 bars) and high-strength (Gr 75)
sound bedrock to achieve the required load reinforcement were utilized to maintain
demand. Three types of foundation retrofits jacket thicknesses under 12 inches, result-
were developed: ing in 60-inch-maximum-diameter columns.
1) Piers-to-rock encapsulating and tied Column capitals were removed to achieve the
into existing piers-to-rock, Figure 2. Existing foundation and in-progress desired reinforcement continuity; however,
2) New caisson caps articulating existing foundation mat for shear wall core. they were rebuilt during the cast operation
piers-to-rock, and to maintain the original aesthetic (Figure 3).
3) Enlarged caisson caps articulating existing pile caps. The forming and casting of circular columns in the building’s con-
strained environment was a costly and troublesome prospect. Shotcrete
was used for columns and capitals to circumvent this difficulty.
Gravity System Concrete was placed and compacted/consolidated at the same time due
Originally designed as a moderately-loaded warehouse, the existing to the force with which the shotcrete is sprayed. A skilled technician
structure is inherently robust. The reprogrammed office building affords hand trowels the last layer, leaving the final product indistinguishable
a load “credit” from the reduced demand. Even with this credit, there from traditional methods. Typically used to line tunnels and swimming
was insufficient capacity to accommodate 17 additional floors. Large pools, this application by the construction team proved invaluable and
spans (up to 48 feet) in the office tower, to achieve expansive column-free was a genuinely innovative and unique feature of Hudson Commons.
areas, amplified the demands at the base of the building where more load WSP faced another interesting challenge in the conversion of the
goes to fewer columns. Conversely, a smaller number of columns had existing roof to a lush landscaped amenity area, which is one of the
the benefit of an overall reduction in the reinforcing steel for the project. numerous green spaces throughout the building (Figure 4). The exist-
The solution implemented by WSP was the retrofitting of existing ing structure had limited load capacity as it was designed initially as an
concrete columns employing new reinforced concrete “jackets.” Before unoccupied roof. The first solution involved a layer of CFRP under the
arriving at this solution, and as with any project involving existing slab with a new concrete topping slab. As the landscape design evolved
structures, the first task was the assessment of existing conditions to include up to 4 feet of soil in some locations, a critical threshold was
and a study of available construction documents. Although some reached making the CFRP-based solution unfeasible (per the provisions
original drawings were available, core samples were extracted from of ACI Committee 440 in the Guide for the Design and Construction
various locations to determine the in-situ compressive strength of of Externally Bonded FRP Systems for Strengthening Concrete Structures).
WSP worked closely with PMG to determine the most cost-effective
approach, and the final structural solution was a secondary support
system of steel beams installed under the existing slab in the green
areas. New steel members were designed as non-composite sections
to eliminate the need to perforate the roof for stud installation. Clips
were installed along the length of the beams to prevent lateral-torsional
buckling (Figure 5).

Lateral System
Hudson Commons required a full upgrade of its lateral load-carrying
system to provide stability of the existing structure and the new tower
above. WSP worked closely with KPF, whose architectural design
included a new circulation and mechanical core eccentrically placed
along the north side of the property to maximize the rentable area.
One of the most notable features of the Hudson Commons core,
however, is its prominence in the architectural expression as it rises
above the existing building. The new spine of the building reads as
such, using exposed architectural concrete to celebrate the material
Figure 3. Column jacket before and after the casting operation. in a tribute to the historic architecture of the neighborhood.
continued on next page
N O V E M B E R 2 019 39
 The two main challenges of the new core system were constructability
and the desire by Cove and PMG for a shoring-free demolition for the
new core (Figure 7), given that shoring systems are costly and may stifle
construction progress. The unique solution implemented by WSP was
to reinforce the existing concrete slab with steel members around the
perimeter of the area to be demolished. Steel members were installed
above and below the slab following the bending moment demand.
Top steel members were removed after casting the core walls. Steel
members below the slab were fitted with studs to trigger composite
action and remained as a permanent bracket connecting the new
core walls with the existing slab. This innovative solution resulted in
significant savings in terms of both cost and schedule.

A Vertical Expansion Showcase

Hudson Commons presented an interesting challenge. Shotcrete column
encasements and retrofitting of various foundation elements allowed the
addition of 17 floors and about 300,000 square feet of rentable area to the
existing structure. Strengthening of the existing roof to accommodate its
conversion to a lush amenity space is a standout. KPF’s design celebrates
this essential element of the structure by leaving the new spine exposed
Figure 4. Rendering of the green amenity space on the roof of the existing building.
Courtesy of Neoscape, Inc. 2017.
as it reaches skyward from the base. Careful attention to constructability
and sequencing contributed significantly to the project’s success.
The new reinforced concrete core runs from foundation to the top Hudson Commons demonstrates unique and innovative solutions
of the building and is comprised of 10,000-psi concrete shear walls to overcome the limitations of adaptive reuse and showcases the pos-
ranging from 12 to 24 inches in thickness (Figure 6). To counteract sibilities of large scale vertical expansion. With developers and cities
the torsional effects of the eccentric core, WSP envisioned a box-like alike striving towards more sustainable solutions to expansion, the
configuration wrapping the entire mechanical and circulation program. relevance of such projects is rapidly accelerating. Hudson
In this closed-box system, the core is placed along existing column lines, Commons topped out in late 2018 and was scheduled to
and the existing columns create breaks in the shear walls analyzed by be tenant-ready by the end of summer 2019.■
considering individual piers at the base building. While this might not
All authors are with WSP.
be ideal from a structural perspective, the benefit of this approach was
the absence of link beams in the base building, which allowed maximum Joseph Provenza is an Associate and the Project Manager.
flexibility with regards to routing services out of the core. Above the Jeffrey Smilow is Executive Vice President, USA Director of Building
Structures, and Principal-in-Charge of the project.
existing roof, the walls are connected through reinforced concrete link
beams to provide adequate lateral stiffness. Three-dimensional finite Yujia Zhai is Vice President of Building Structures and the Project Director.
element analysis software was used to model both the existing and new Motaz Elfahal is Structural Analysis Manager and Vice President of Building
Structures.
structure allowing for an optimized and efficient structural design.

Figure 5. The underside of roof slab reinforced Figure 6. Reinforced concrete core emerging above the roof slab of the Figure 7. Shoring-free slab demolition for the
with additional non-composite steel beams. existing building. core with temporary steel above the slab and
permanent steel below the slab.

40 STRUCTURE magazine
 structural SUSTAINABILITY
Resilience: A Rallying
Cry We Can Amplify
By Kate Stillwell

R esilience may be the phrase of the decade, but it is not

a new concept. Structural engineers have been building
resilience all along; it is only now that others are catching on.
And, as structural engineers, there are tangible steps we can
take to amplify the resilience we build.
Consider the broader meaning of resilience: the ability of a
person or system to adapt to shock and return to a “new normal.” Figure 1. Sand Palace Mexico Beach, Florida.

In this context, structural engineers need to ask: is structural design be next. What has become abundantly clear is the lack of redundancy
truly resilient, i.e., does it achieve its performance objectives, if related in our social and economic systems.
elements of resilience are lacking? Most engineers think only about Vulnerabilities exist across all dimensions of resilience, including
the building. However, a building is only one part of the physical infrastructure/lifelines, post-event governance, and social connect-
infrastructure, and the physical infrastructure is only one part of a edness. Making this last point by counter-example, the research of
city and community. Daniel Aldrich at Northeastern University convincingly shows that
Some frameworks for thinking about resilience have a dizzying communities with high degrees of social connectedness have demon-
array of “spokes.” As a simpler alternative, consider the metaphor of strably better disaster outcomes – not only survival and displacement
stability: resilience as a three-legged stool. Resilient structural design rates but also the speed of recovery in the medium- to long-term. And
can only serve its intended purpose if the other legs of the stool are “social connectedness” extends to electronic connectedness. Social
also present. Are they? media as resilience-builder? Heck, yes!
The three legs are physical resilience (including safe buildings, However, perhaps most fragile is our financial structure. Even a
lifelines, data), social resilience (including neighborhood cohesion, cursory glance at post-disaster financial systems reveals a staggering
effective governance, NGOs, and many others), and financial resil- lack of savings at both macro and micro scales.
ience (including public aid, insurance, banks). At the federal level, FEMA continues to provide post-disaster
After the shock of a natural disaster, what good are safe buildings if Individual Assistance grants, but the public is becoming more and
no one stays to live in them? more pessimistic about the timeliness and availability of federal relief.
The classic case in point: Hurricane Katrina in 2005. Fully 40% of Likewise, FEMA messaging itself has shifted to downward-manage
the residents of New Orleans left and never returned. The population public expectations on grant amounts.
ticked back up but was mostly comprised of newcomers. And now, a At the municipal and state levels, public entities must constantly
mere 14 years later, New Orleans suffered another debilitating flood. balance competing priorities. It might win votes in the short-term to
The last thing structural engineers should want is for their building to use limited resources to solve here-and-now problems, but this puts
be “resilient in a vacuum,” i.e., functional but abandoned, whether for a strain on the number of resources available for emergency reserves.
lack of occupants, finances, infrastructure, or political will (Figure 1). Worst of all is the systematic lack of savings at the individual level.
When structural engineers understand and incorporate these other, Annual surveys by Bankrate repeatedly show that a staggering majority
interrelated parts of resilience, they increase the chances that their of Americans lack even $1,000 in savings. What this means is that
designs will achieve true resilience. It will help prevent their good the unanticipated expenses of a natural disaster – even just the cost
work designing reliability, predictability, redundancy, and reparability of evacuation – could tip a family into a spiral of debt.
from going to waste. The leverage of financial resilience cannot be understated. Case
However, how do structural engineers incorporate inter-disciplinary studies from two different historical and cultural contexts make
notions of resilience into their design? It will vary across context, this point.
project, physical setting, and ownership, but the intent of this article
is to provide food for thought.
Recovery is Driven by Money: Case Studies
Figure 2 is a photo of the 1906 San Francisco earthquake showing a
Redundancy: Notably Lacking group of people on Potrero Hill, smoke billowing in the background.
We have all seen the social and economic disruption from extreme Their city is in flames, yet they are smiling, as if undaunted. They
disasters, and it is frightening to imagine that your home town could possibly foresaw what would happen over the next decade: massive

42 STRUCTURE magazine
massive public and private investment, $50 million at the time. In business at the “top of their list” for post-disaster work. This way,
today’s dollars, considering the population in 1906, this amounts to they limit the degree and expense of follow-on damage such as
$2,500 per capita – which is astounding because it is 5 to 10 times mold or sprinkler leakage.
the per-capita post-disaster disbursements that are typical in recent The Napa earthquake occurred early on a Sunday morning. One
decades. This allowed San Francisco to bounce back so definitively three-story building in the city center, used as an administrative center
that it hosted the 1915 Pan-Pacific Expo and established itself as for processing legal documents, was unoccupied at the time. From
an international destination. the exterior, there was no visible damage. Therefore, no one entered
INFO SPECS
Something similar happened in the decade after the M7.7 2001 the building until Monday morning, more than 24 hours later. By
Bhuj (India) earthquake. It was a tragic disaster for thousands FileName:
of 19-1670_Ad_1/2Island
then, extensive Structure_July_Bridge
flooding hadRepair Solutions due
occurred PagetoSize: 5w" x 7.5h"
a single bleed head
sprinkler
people, but at the macro level, it was a financial success story.Job#: The19-1670 that had sheared PR#: N/A off. Many of the legal documents Number of Pages: 1
were permanently
state and national government 1 1 4 4quickly
E . N e w pinvested
o r t C e n t $2
e r Dbillion
r.
Artist:
into Georgina Morra Email: damaged.
and irreplaceably gmorra@mapei.com Bleed: Yes Amount: .125"
the rebuild. This had the flywheel effect of attracting another $10
Deerfield Beach, FL 33442 Date: June 7, 2019 10:29 AM
The point is not that it is necessary to strengthen Colors: CMYK Process, 4/0
the building so
billion or more from the private market, enough to create momen- that none of the sprinkler heads will shear off; there will always
N O T E : C O L O R S V I E W E D O N - S C R E E N A R E I N T E N D E D F O R V I S U A L R E F E R E N C E O N L Y A N D M A Y N O T M A T C H T H E F I N A L P R I N T E D P R O D U C T. be

tum for a remarkable economic boom.

Over the following decade, the state of
Gujarat experienced 10% GDP growth,
and the employment of women doubled.
Some have gone so far as to call this the MAPEI bridges the
gap with concrete
“Gujarat miracle.”

Extending Our Reach:

Contingency-Planning repair solutions
Disasters cause unanticipated conse-
quences unrelated to damage, which
have real costs and affect recovery, and
structural engineers have the know-how
to extend resilience-building beyond just
construction documents. Here are two
examples from the M6.0 Napa earthquake
in 2014.

ADVERTISEMENT–For Advertiser Information, visit STRUCTUREmag.org

This first example demonstrates how the
client can gain critical information for
contingency-planning if the structural
engineer performs an assessment of the
immediate vicinity.
Velo Pizza is a thriving local business
in Napa in a historic masonry building.
Carroll Avenue Bridge
Takoma Park, MD Corrosion protection
The owners had done the right thing
Bear Cut Bridge
and had retrofitted their building. When Key Biscayne, FL
the 2014 M6.0 earthquake struck, the
employees and the customers all stayed
safe, and there was basically no damage.
Initially, they had a green tag, “safe to
occupy.” Then a red tag was added below I-80 Verdi Bridge

the green tag – Unsafe. What was that all Concrete repair mortars Verdi, NV

about? The building next door, also an

unreinforced masonry building, was not
retrofitted, and there was the dangerous
possibility that, in an aftershock, bricks
from next door would fall through Velo’s
roof and hurt someone. At no fault of
their own, Velo had to close temporar-
ily and lost revenue. The employees lost
income. If Velo knew about this con-
tingency (maybe they did!), they could
JEA Northside Generating Station
Jackonville, FL Products for structural strengthening
have made specific plans to mitigate its
financial consequences.
The other example illustrates the poten-
tial value for a client to engage a repair
contractor on retainer, putting their

N O V E M B E R 2 019 43
 surprises you cannot plan for. The The author set out to tackle some
point is to make a contingency plan of these interrelated resilience chal-
so that someone goes to the build- lenges. In the choice between social
ing within an hour and turns off the versus economic challenges, it was
sprinklers, thus limiting the damage. natural to gravitate toward financial,
being an engineer and comfortable
Practical Steps to with numbers. The financial challenge
of resilience is two-fold: not only do
Amplify Resilience Americans have an abysmally low
Structural engineers are uniquely savings rate, but 9 out of 10 people
influential in building resilience in forego non-mandatory insurance for
all its forms. We can help clients the most severe disasters like earth-
build social and financial resilience quake and flood, which disrupt life
as well as structural resilience. The for whole communities, whether or not
Table is only a starting point. When an individual’s property suffers damage.
we take tangible steps to help build This led the author to a commitment
the interrelated parts of resilience, to build financial resilience for both
it will amplify the resilience of our individuals and communities after a
structural design. The Table pres- natural disaster. Even though not cur-
ents actionable ideas for SEs to help rently practicing engineering, there is
promote address financial and social still a strong alliance for the author with
resilience. Figure 2. San Franciscans on Potrero Hill. the SE community because the mission
remains fundamentally the same as the
resilience-building motive of structural engineers.
One SE’s Professional Journey One of the best things about being a structural engineer is the grati-
The author became a structural engineer to make the world a better fication of making the world safer and more resilient. And
place – to save lives and protect livelihoods. Starting to practice in that gratification only increases when we extend our services
1998, Hurricane Katrina in 2005 presented a professional crisis: Are to build resilience more broadly. Onward!■
safe buildings serving their purpose if no one stays to live in them?
Our social and economic systems are much more fragile than our Kate Stillwell is the Founder and CEO of Jumpstart, and she builds financial
buildings. How can we bring the talents of our profession to these resilience through parametric insurance. Kate is SEAONC Past President
larger challenges of resilience? What are the best ways for us to bolster and a SEAONC Fellow. She also co-founded the U.S. Resiliency Council
other, interrelated systems so that the built environment can more and the GEM Foundation.
effectively do the job we are designing it to do?

Table of actionable ideas to promote resilience.

Actionable Ideas Financial Resilience Social Resilience

At the building-specific level • Coordinate our design with the insurance broker • Offer client services to propose standards
to develop a custom policy that is tied to struc- and incentives for neighboring buildings or
tural performance community redevelopment to achieve resil-
ience. This is particularly relevant to larger
developments.
At the organizational level • Advise clients on what level of downtime, and • Encourage risk managers to become mem-
therefore time-induced losses, they may experi- bers of interdisciplinary resilience-building
ence to assist them in determining the amount of organizations such as EERI or the Earthquake
business interruption insurance to buy Country Alliance
• Advise clients to hire structural engineers or other • Offer client services for evaluation of the other
professionals “on-call” to stem post-disaster losses aspects of resilience – for example, cost-benefit
(see the example in the article) analyses, probabilistic studies, lifeline interde-
pendency evaluations, etc.
At the individual level • Encourage clients to add employee benefits that • Employer-sponsored activities such as athletics
bolster post-disaster financial stability, such as • Employer-specific groups on social networks,
savings plans or insurance policies that pay right such as Facebook, for the sole use of post-
away. The availability of funds makes it more disaster communication and coordination
likely for employees to come back to work. This is
especially important for organizations that provide
post-disaster services such as utility districts and
hospitals (and structural engineers!)

44 STRUCTURE magazine
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 structural REHABILITATION
Adaptive Reuse of the Apex Hosiery
Company Building
Part 1: History of the Philadelphia Demolition
Ordinance and the Apex Hosiery Building
By D. Matthew Stuart, P.E., S.E., P.Eng, F.ASCE, F.SEI, A.NAFE, SECB

T his four-part series discusses how the collapse of a building

during a demolition operation in Philadelphia in 2013, which
resulted in several fatalities, led to enactment of a City Ordinance to
prevent similar future calamities. As a result of the Ordinance, the
author became involved with the structural investigation, review of
the Site Safety Demolition Plan, and Demolition Special Inspections
associated with the adaptive reuse of the Apex Hosiery Company
Building located in Philadelphia.
As a result of the investigation, a unique type of reinforced concrete
Figure 1. The aftermath of a June 5, 2013, building collapse associated with
flat slab construction, the SMI System, was encountered. The author
demolition of a series of adjoining two- and four-story mercantile loft structures
had previously dealt with this type of construction at another building onto the immediately adjacent, one-story Salvation Army Thrift Store building in
in Philadelphia. The findings of the investigation assisted with the Philadelphia. Courtesy of Lindsay Lazarski, WHYY.
successful completion of both the partial demolition of the existing
structure and the success of the adaptive reuse project. found to be responsible for the fatalities and injuries by a civil court
jury. The ruling resulted in a total settlement of $227 million for the
individuals that were killed or injured in the incident.
Building Demolition Collapse
On June 5, 2013, a building associated with the demolition of a series
of adjoining two- and four-story mercantile loft structures collapsed
City of Philadelphia Demolition Ordinance
onto the immediately adjacent, one-story Salvation Army Thrift Store At the time of the collapse, the City of Philadelphia did not require
building. The thrift store was located at the corner of South 22nd Street demolition contractors to document their qualifications. However,
and Market Street in Philadelphia and was open and full of shoppers as a result of the incident, the City announced two days after the
at the time of the collapse. The collapse resulted in the death of six collapse that new demolition rules and standards would be enacted
individuals and seriously injured fourteen people. to prevent similar tragedies in the future.
The unintended collapse was precipitated by an unsupported, four- The new City Ordinance documented several new demolition per-
story masonry brick wall that was immediately adjacent to the Thrift mitting requirements, including:
Store. The unstable condition was created when the demolition contrac- 1) Post a notice of the demolition of a structure and distribute
tor removed most of the floor and roof framing, originally connected notifications to properties adjacent to and near the building
to the same wall, using an to be demolished.
18-Ton excavator. The after- 2) Site plan.
math of the collapse can be 3) Demolition schedule.
seen in Figure 1. 4) Special Inspections.
As a result of the incident, 5) The submission of a Site Safety Demolition Plan or “engineer-
both the demolition con- ing survey” as required by OSHA that includes:
tractor and operator of the a) Details of the type of construction and condition of the
excavator were convicted of structure to be demolished.
six counts of involuntary b) Inspection details of the structural conditions of the
manslaughter and sentenced adjoining properties.
to prison. Six months after c) Description of the means and methods of protecting
the incident, OSHA also adjacent structures.
levied fines against the d) Description of the method of demolition.
demolition contractor’s and e) Details of potential hazards.
excavator’s companies. Also, f ) Confirmation of the presence of underground utilities.
the project developer, the g) Description of safety and environmental issues.
architect who had been hired Continuous demolition Special Inspections were also required by the
Figure 2. Apex Hosiery Company Building to monitor the demolition, Ordinance, and must also be overseen by a licensed structural professional
located in Philadelphia – prior to renovation. and the Salvation Army were engineer for the following conditions:

46 STRUCTURE magazine
Figure 3. The 6-story structure was constructed as a reinforced concrete,
flat slab supported by round and rectangular columns with column
capitals and drop panels.

1) Demolition of a building in excess of three stories

or 40 feet in height.
2) Where the use of mechanized demolition as a part
of the Site Safety Demolition Plan, or SSDP, is
approved by a licensed structural engineer.

Site Safety Demolition Plan and

Special Inspection Project
As a result of the demolition Ordinance, the author
became involved in a number of demolition projects.
The services provided to clients for demolition projects
included the development of demolition bid documents,
which are not required by the Ordinance, the engineering Figure 4. Two-way reinforcing was confirmed to be orthogonal and parallel to
review of Site Safety Demolition Plans (SSDP) devel- the main column grids and did not include any diagonal 4-way reinforcing.
oped by demolition contractors, and Special Inspections
that are performed by a separate inspection and testing division of
the author’s firm, Pennoni. One of the most interesting demolition
Apex Hosiery Company Building History
projects that the author has been involved with was the adaptive reuse The original building was designed by Architect Frederick Muhlenberg
of the Apex Hosiery Company Building located in Philadelphia, for use by the Apex Hosiery Company and built in the 1920s; the
shown in Figure 2. building was in use until April 1954 when the factory was closed.
The renovation of the existing, six-story reinforced concrete manu- Following a series of ownership changes, the School District of
facturing building involved the demolition of the Penthouse, roof, and Philadelphia purchased the building in 1967, and the factory floors
6th and 5th floors, leaving a three-story structure that was to be used were converted into classrooms for a middle school. In June 1984,
as affordable rental housing. Structural engineering services for the
project involved both pre-demolition and post-demolition condi-
tion assessments of the structure and façade, and Special Inspections
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during the demolition phase. The pre-demolition survey included Demos at www.struware.com
the installation of several crack monitors at selected locations within
the portions of the building that were to remain for the purpose Wind, Seismic, Snow, etc. Struware’s Code Search program calculates these and
other loadings for all codes based on the IBC or ASCE7 in just minutes (see online
of monitoring movement of the structure during the demolition video). Also calculates wind loads on rooftop equipment, signs, walls, chimneys,
phase. The pre-demolition effort also involved a peer review of the trussed towers, tanks and more. ($250.00).
SSDP that had already been approved by another engineering firm. CMU or Tilt-up Concrete Walls Analyze solid walls for out of plane loading and
In addition, the author completed a gravity load capacity analysis panel legs next to or between openings by automatically calculating loads to the wall
of the remaining structure to confirm the feasibility of the proposed leg from vertical and horizontal loads at the opening. ($75.00 ea)
adaptive reuse of the building. Because there were no existing Floor Vibration Program to analyze floors with steel beams and/or steel joist.
structural drawings for the building, the load-carrying capacity Compare up to 4 systems side by side ($75.00).
was determined via small, exploratory demolished openings in Concrete beam/slab Program to provide bending, shear and/or torsional reinforcing.
the existing concrete slab, used to observe and document the size, Quick and easy to use ($45.00).
spacing, and concrete cover of the internal reinforcing.

N O V E M B E R 2 019 47
 the school was renamed Roberto Clemente Middle School and
remained in use until the mid-1990s when a new Clemente school
building was constructed elsewhere in the city. The building was
subsequently used for storage but became deteriorated and was
abandoned in 2007.

Description of Structure
The footprint of the building, which somewhat resembled the
shape of the letter F, occupied most of the triangular block
bounded by North 5th Street, Rising Sun Avenue, and West
Luzerne Street. The 6-story structure was constructed as a rein-
forced concrete, flat slab supported by round and rectangular
columns with column capitals and drop panels, as shown in
Figure 3, page 47. Laboratory material testing of the existing
reinforcing samples and in situ non-destructive evaluation of
the existing concrete compressive strength were performed along
with field measurements of the critical structural components of
a typical framed level. The average in situ concrete compressive
strength of 6,000 psi was established via both a Schmidt Impact
Hammer and a CAPO-TEST pullout device.
Based on observations at several exploratory openings in the
south end of the building, the two-way reinforcing was con-
firmed to be orthogonal and parallel to the main column grids
and did not include any diagonal 4-way reinforcing (Figure 4, Figure 5. Based on observations, the reinforcing was confirmed to be the SMI, or
page 47). The top reinforcing bars were also “trussed,” in other Smulski Method system, which involved the use of smooth, round concentric rings,
words bent down, towards the bottom of the slab near the edge or hoops, of small-diameter steel bars. Courtesy of ACI Journal Proceedings, 1918.
A Test of the SMI System of Flat Slab by Edward Smulski
of the drop panels and thus became the bottom reinforcing, a
common method of rebar placement during the era in which
the building was constructed.
Based on observations at additional exploratory openings in
the north end of the building, the reinforcing was confirmed to
be the SMI or Smulski Method system, which involved the use
AutoTight®
of smooth, round concentric rings, or hoops, of small-diameter TIGHTER CONNECTIONS
steel bars as illustrated in Figure 5. The north and south sections
of the main rectangular building footprint were separated by an BETTER PERFORMANCE
expansion joint; therefore, it was evident that the separate north
and south portions of the building had been built using two
distinctly different methods of two-way flat slab construction

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that were available during the era the facility was constructed.
Why this situation occurred during the construction of the
building was unclear, particularly in light of a 1922 article from
a textile industry publication that indicated a single design/
build contractor, Beling-Bush Company, Inc., was awarded the
project. However, a review of a historic Sanborn Fire Insurance
 
Map of the property indicates that the north and south sec-
tions of the building were constructed at different times. The
northern half appears to have been completed first in 1923
by Beling-Bush Company, Inc., while the southern half was
completed in 1925 presumably by another contractor. Also,
per the same map, the eastern wings of the building
associated with the southern half of the facility were
completed even later, in 1929.■

Part 2 of this series will provide more details on the SMI

system and peer review of the site safety demolition plan.

ZERO LOOSENESS
Matthew Stuart is the Senior Structural Engineer at Pennoni Associates Inc.
in Philadelphia, PA. (mstuart@pennoni.com) PH: (360) 378-9484 – WWW.COMMINSMFG.COM

48 STRUCTURE magazine
Contact CoreBrace at:
5789 West Wells Park Road
West Jordan, UT 84081
801.280.0701
corebrace.com
info@corebrace.com
 professional ISSUES
Upfront and In Need
Affordable Housing Explained
By Dallas Erwin and Kate Peterson

A ffordable housing is in the news more than ever before.

As rising rents and harrowing rates of homelessness echo
across the country, housing advocates are relieved to see the
spotlight finally shine on the need for this essential community
resource, but their relief is shortlived. All this attention is the
result of millions of families searching for a stable place to call
833 Bryant rendering.
home. The National Low Income Housing Coalition (NLIHC)
estimates that there’s a shortage of 7.2 million homes. Innovative partnerships are slowly creating positive change. To build more
and better housing for the people that need it most, resourceful engineers are necessary. Affordable housing building trends
offer a glimpse into the sweeping social change affecting neighborhoods and how engineers can make a difference.

From an engineer’s perspective, affordable housing and market-rate

Affordable Housing developments are similar in many ways. What is different is the funding
The phrase “affordable housing” isn’t always understood uniformly and, consequently, the planning. All well-executed real estate develop-
outside of the industry – essentially it offers subsidized homes for ments have concise planning, but affordable housing needs the details
low-income individuals to help free them from rent burden (more earlier than what is commonly expected with market-rate properties.
than 30% of income going to rent), so they have more resources to Mercy Housing’s seasoned real estate developer, Kuhl Brown, offers
spend on other essentials like food, healthcare, and education. insight into the affordable housing industry and what that means for the
Mercy Housing is an affordable housing nonprofit; with a presence engineering aspect of planning: “We often need engineering design input
in 41 states, they have over 37-years’ experience serving low-income and insight early, requiring higher concept detail upfront. Affordable
families, veterans, seniors, and people with special needs. Mercy Housing housing funding is typically competitive, and pre-development is a
partners with communities to make long-term commitments, resulting huge component of being successful.” The subsidies Kuhl references
in positive, measurable outcomes for residents and neighborhoods. are the Low-Income Housing Tax Credits (LIHTC). Pronounced
colloquially as ‘lie-tech,’ it is not a buzz
word, but rather the lifeblood of affordable
housing. Created in 1986 under the Reagan
Professional Master in Structural Administration, this vital funding source
Design of Tall Buildings raises private equity for affordable hous-

PMTB
ing through the allocation of federal tax
Dreaming of getting a credits going toward the rehabilitation and
ADVERTISEMENT–For Advertiser Information, visit STRUCTUREmag.org

professional master’s degree construction of below-market-rate housing

but can’t leave your job? for low-income tenants. LIHTC funding is
Earn a professional master’s excruciatingly competitive, while compli-
degree in structural design of tall ance is held to the highest standard and
buildings from an internationally administered by state housing finance agen-
recognized institution through cies. Deadlines are strict; you can typically
blended learning only apply for LIHTC funding twice a year,
[online + in-class] but each state is different. Kuhl confirms
approach that “construction type has a huge impact
For more info because land and sites are scarce and we
solutions@ait.ac.th are competing for the same land and labor
Apply now! +(662) 524 6388
solutions.ait.ac.th/pmtb costs that market-rate developers can fund
through private equity.”
Offered by There are several takeaways for the struc-
Civil and Infrastructure Engineering Department, tural engineer. First, the project will be
School of Engineering and Technology, Asian Institute of Technology (AIT), Thailand
front-loaded more than a typical project,
meaning more fee will be needed in the

50 STRUCTURE magazine
planning and schematic design phases. Also, the level of detail required
early will be greater than normal. Many structural engineers are
Ready to Roll Up Your Sleeves?
only used to selecting the structural system and roughing out typical Tightened budgets and deadlines make 3-D modeling increasingly
member sizes during schematics but, for affordable housing projects, popular to reduce planning errors. Modular construction is another
the architectural design is very far advanced, so the structural design trend that is increasingly appealing in the affordable housing scene.
needs to be too. Beam and column sizes and wall thicknesses need to Structural engineers with experience and know-how with evolving
be determined accurately for both coordination and accurate pricing. technologies focused on cost-effective quality construction (low main-
LIHTC geographic allocation tenance), and those that have the
can be enhanced through a 30% They [firms with affordable housing experience] are communication skills to engage
basis boost that is decided by the familiar with our unique requirements; these architects with the developer, architect, and
U.S. Department of Housing and and engineers know our design priorities and often how we choose contractor in project development
Urban Development (HUD). and problem-solving, have a leg
who to go with – experience and trust. It is particularly appealing
HUD’s Qualified Census Tract up. Kuhl notes that “We are always
(QCT) is the mapping system when all architects and engineers are under one firm – again, this asking, is there a more efficient pro-
that annually chooses tracts to be is friendly to time and cost. Because of our financing structures, duction possibility offsite? Some of
included as a QCT based on the we are trying to be more efficient with less money. Especially in these offsite construction methods
tract’s income. This often becomes competitive markets, we need to maximize scale and units on can cut down on construction time
essential in determining the via- smaller urban sites. The same problems that are common by six to eight months. Efficient
bility of where LIHTC funding structural and civil engineering is
can go. The decision ultimately for market-rate can pop up with affordable housing.” essential when it comes to doing
changes the substantial up-front ~ Kuhl Brown, Mercy Housing more with less.”
planning for engineers due to each When Kuhl is asked what engi-
site locations’ unique geological and zoning concerns. QCTs are com- neers can do if they are interested in affordable housing, he recommends
monly found in lower-income and middle-income areas and often in to simply “Get out and tour some; most developers love showing off what
higher-density urban areas. they have built!” Nonprofits like Mercy Housing do not just build homes;
Additionally, state and city ordinances require lengthier and more they build a sense of community. Creative collaboration is a theme of
detailed applications for affordable housing. “We cannot move for- not only affordable housing construction but the entire industry as well.
ward with construction until city and state applications are awarded, Housing is a complex, multifaceted issue that touches so many aspects
plus capital campaigns must be in place prior as well. We are held of society, and partnerships are vital. The affordable housing industry
to an even higher standard because our funding provides tax credits; continues to measure and quantify the far-reaching benefits
certain states require amenity packages that are at or above market of stable homes. From engineers to civic leaders and even
rate developments, depending on the market.” healthcare professionals, the message is clear, home is hope.■
During the initial planning, developers first look for need – does this
community truly need below-market-rate housing? There is a myriad of Dallas Erwin is Mercy Housing’s Content Manager. (derwin@mercyhousing.org)
economic and sociopolitical factors that play into this. Secondly, they
Kate Peterson is the Senior Vice President of Marketing and
think about opportunity – zoning and availability factors must fall into
Communications for Mercy Housing. (kpeterson@mercyhousing.org)
place. Thirdly, perhaps the most challenging, funding – LIHTC is part
of this equation and notably the country’s
largest affordable housing resource, but
it is not the only available opportunity.
Local and other soft funding sources can
be critical for success. There are no quick
answers to these questions.
The value of the LIHTC credits dropped

ADVERTISEMENT–For Advertiser Information, visit STRUCTUREmag.org

recently with the federal tax reform that
lowered corporation and business tax rates
and thus their need for credits. Additional

MOST
headwinds are construction costs, which THE
are climbing nationally but also some-
what market dependent. Kuhl points
to resourcefulness and creativity as the ICC-ES APPROVALS
paths forward; “We are always balancing FOR MECHANICAL AND ADHESIVE ANCHORS
cost and need with even small things like IN THE INDUSTRY
parking and other parts of the develop-
ment that may be seemingly simple, yet
complex from a development and zoning
or entitlement perspective.” Affordable
housing developers often use engineers
and firms that have previous experience WWW.ANCHORS.DEWALT.COM
with below-market-rate housing for prac- Copyright ©2019 D E WALT
ticality and cost saving purposes.
DW_STRUCTURE_112019_QtrPage_AD.indd 1 10/8/19 1:50 PM
N O V E M B E R 2 019 51
 NCSEA
NCSEA News
National Council of Structural Engineers Associations
2019 NCSEA Special Awards Honorees
The Special Awards honor individuals who have provided outstanding service
and commitment to the association and to the structural engineering field. These
prestigious awards will be presented at the NCSEA Awards Celebration taking
place at the Structural Engineering Summit in Anaheim, CA, on November 14,
2019. Visit www.ncsea.com to learn more about the Special Awards and about
this year's recipients.
Congratulations to the 2019 Special Awards Honorees!

NCSEA Service Award

This award is presented to an individual who has worked for the betterment of NCSEA to a degree that is beyond the norm of
volunteerism. It is given to someone who has made a clear and indisputable contribution to the organization and the profession.

Ben Nelson, P.E., is Structural Division Manager and Chairman of the Board for Martin/Martin
Consulting Engineers, based in Lakewood, Colorado. He has practiced structural engineering for over
35 years, all with the same firm. He served on the Board of the Structural Engineers Association of
Colorado (SEAC) for 5 years and was President in 1999. He was SEAC’s delegate to NCSEA from
2002-2010 and was elected to the NCSEA Board of Directors in 2007, serving 7 years, including
NCSEA President in 2012-2013.
While NCSEA President, Mr. Nelson founded the initial Young Member Group (YMG) which
evolved into the YMG Support Committee as well as the YMG scholarship program to encourage
greater participation at the NCSEA Annual Conference, later the NCSEA Summit. He is most proud
of the growth of YMGs throughout nearly all of NCSEA’s Member Organizations and their substantive
impact to the future of NCSEA and the structural engineering profession.
Mr. Nelson also established NCSEA’s Susan Frey Educator Award in 2014 and has served on NCSEA’s
Awards Committee since 2013. He has presented numerous talks and sessions to structural engineers
throughout the country. In his 17 years with NCSEA, he also actively served on many NCSEA committees
including Advocacy, Winter Institute, Structural Engineering Summit, Continuing Education, and
Member Organization Liaison/Communications.

Robert Cornforth Award

This award is presented to an individual for exceptional dedication and exemplary service to an NCSEA Member Organization as
well as to the structural engineering profession.

Thomas A. DiBlasi, P.E., SECB, has been a practicing engineer for over 34 years and is a licensed
Professional Engineer in 14 states. Over the past 34 years, he has moved the profession forward by
being an active member of many boards, associations, and committees, and also by encouraging staff
and future generations of structural engineers to participate in professional learning opportunities and
to get involved.
Mr. DiBlasi is the Principal/President of DiBlasi Associates. The success of DiBlasi Associates is due to
DiBlasi's own dedication to the field as well as his mentoring and support of his small, yet impressive
staff of only four.
He has been involved with the Structural Engineers Coalition of ACEC/CT since its inception in the
1980’s. He carried over that support to NCSEA, where he represented Connecticut as their delegate, he
served as President of the Board of Directors in 2011-2012, and where he currently sits as Chair of the
Code Advisory Committee.
Mr. DiBlasi has made important contributions to the field at both the state and national level which is
highlighted though his tireless work on committees that focus on a variety of aspects of the field from
professionalism to code writing, to supporting future engineers.

52 STRUCTURE magazine
 News from the National Council of Structural Engineers Associations

Susan M. Frey NCSEA Educator Award

This award, established to honor the memory of Sue Frey, one of NCSEA’s finest educators, is
presented to an individual who has a genuine interest in, and extraordinary talent for, effective
instruction for practicing structural engineers.
Dr. S. K. Ghosh heads the consulting practice, S. K. Ghosh
Associates LLC, Palatine, Illinois, now a subsidiary of the
International Code Council. Dr. Ghosh is active on many
national technical committees, is an Honorary Member of ACI,
and is a Fellow of ASCE, SEI, and PCI. He is a member of
ACI Committee 318, Standard Building Code, and the ASCE 7
Standard Committee (Minimum Design Loads for Buildings and
Other Structures). He is a former member of the Board of Directors
of ACI, EERI (Earthquake Engineering Research Institute), and
BSSC (Building Seismic Safety Council). He is a member of the
Board of Governors of ASCE’s Structural Engineering Institute.
Dr. Ghosh has influenced seismic design provisions in the United
States for many years. In addition to authoring many publications
in the area of structural design, Dr. Ghosh has investigated and
reported on structural performance in most recent earthquakes.

James Delahay Award

This award is presented at the recommendation of the NCSEA Code Advisory Committee to recognize outstanding individual contributions
towards the development of building codes and standards. It is given in the spirit of its namesake, a person who made a long and lasting
contribution to the code development process.
Kelly E. Cobeen, S.E., joined WJE in 2008 with twenty-three years of experience in structural
design, working in a wide range of project types, sizes, and construction materials. She has a special
interest in seismic resistance of light-frame construction, applicable to new construction and seismic
upgrade of existing buildings.
Ms. Cobeen has been involved in numerous code development, research, and educational activities.
Her code development activities include involvement in the NEHRP Recommended Provisions for
Seismic Regulations for New Buildings, as well as the International Building Code and International
Residential Code development. Her educational activities include coauthoring the Design of Wood
Structures textbook, teaching wood design at University of California, Berkeley, and teaching seminars
for professional organizations.
In addition to light-frame construction, Ms. Cobeen has extensive experience in design, evaluation, and
seismic upgrade of a wide range of building types, including concrete shear wall and frame buildings,
steel braced and moment frame buildings, masonry buildings, and masonry infill buildings.

NCSEA Webinars Register by visiting www.ncsea.com.

November 7, 2019 December 5, 2019
Permanent Bracing for Metal Plate Connected ASCE 7-16 Determining Component and Cladding
Wood Trusses Wind Pressures for Roofs
Jim Vogt, P.E. William L. Coulbourne, P.E., SECB, F. SEI, F.ASCE

November 19, 2019 December 10, 2019

Ground Improvement for Structural Engineers Mass Timber Structural Floor & Roof Design
Jeffrey Hill, P.E. Dr. Scott Breneman

Courses award 1.5 hours of continuing education after the completion of a quiz. Diamond Review approved in all 50 states.

N O V E M B E R 2 019 53
 SEI Update
Learning / Networking

STRUCTURAL STRUCTURES Sponsor/Exhibit

CONGRESS 2020
ENGINEERING
INSTITUTE to showcase
St. Louis, Missouri I April 5-8 your brand.

Registration is open! NEW Group registration discount is available. Check out the program and sessions and plan your schedule.
www.structurescongress.org

Visit the ASCE Bookstore at the NCSEA Summit

November 12-15 in Anaheim, CA.
Check out ASCE 7 Online and Hazard Tool demos and enter for a chance to win a 6-month individual
subscription to ASCE 7 Online.

Students/Young Professionals
Welcome Joseph Burns to the SEI Futures Fund Board
Joseph G. Burns, P.E., S.E., CEng, F.IStructE, F.ASCE, F.IABSE, FAIA, Managing Principal, Thornton Tomasetti, joined
the SEI Futures Fund Board on October 1 for a five-year term. With more than 35 years of experience, Joe is a passionate
advocate for the deeper integration of architecture and engineering, which he promotes through innovation, collaboration,
and leadership. A member of Thornton Tomasetti’s board of directors, his practice is based in Chicago while overseeing the
firm’s operations in the Middle East and Brazil.
Joe comments, “I am very excited to join the SEI Futures Fund Board, and engaging in its challenge of supporting the
growth and advancement of future generations in the structural engineering profession. Early in my career, I became
engaged with the ASCE Committee on Aesthetics in Design. This gave me an opportunity to collaborate with structural engineers beyond
my experiences at work, and led to a series of leadership positions within the ASCE Structural Division as chairman of the Committee on
Aesthetics in Design, Chair of the SEI Technical Activities Committee on Special Design Issues, and member of other committees like the
Tall Building Committee. This certainly had a big impact on my professional development and evolution. I am delighted to be in a posi-
tion to assist our next generation the way I was supported and mentored as a young engineer.”

SEI Online
Structural
Engineering
Channel
Podcast
Check out recent podcasts with SEI leaders on Confidential Reporting on
Structural Safety Now in the U.S., Performance-Based Wind Design, and more at
https://engineeringmanagementinstitute.org/tsec-podcast.

SEI on Twitter SEI on Facebook SEI Standards

Follow us: @ASCE_SEI Visit www.asce.org/SEIStandards to:
Follow us: @SEIofASCE
View ASCE 7 development cycle

54 STRUCTURE magazine
 News of the Structural Engineering Institute of ASCE

Membership
From Glenn Bell on Serving as SEI President FY20
Structural Engineering is the greatest profession on the organizations. However, there is so much more to be done. We live
planet. The work is challenging and meaningful, we and work in turbulent times where the pace of change brought on by
serve society in critically important ways, our members technological, societal, political, and economic influences is staggering.
are of outstanding caliber and integrity, and we have While we may find these changes unsettling, I think we live in the most
fantastic professional organizations like ASCE/SEI to exciting time for the future of structural engineering because society
propel us forward. will need highly qualified and creative structural engineers to meet its
My career to date has encompassed 45 years at future challenges. To secure this opportunity, we must simultaneously
Simpson Gumpertz & Heger Inc., 24 of them as its CEO and/or develop a new breed of structural engineers while elevating our profes-
Board Chair. The work has been fascinating, has stretched me in sion to play more impactful roles.
directions I never expected, and has offered a secure and comfortable In advancing structural engineers and structural engineering, these
means of living. My colleagues are exceptional individuals. are particular topics I am passionate about:
While I have long been involved in ASCE and SEI, some years ago, • Young Professionals: I am tremendously inspired by the
I decided that when I gave up my CEO hat and had more time as I creativity, energy, and brilliance of our youth. The role of we
transitioned toward retirement, I would give back to this great profes- “more mature” of the SEI leaders should be to unleash and
sion by stepping up my professional leadership. A pivotal event for me enable that youthful talent and ambition.
was a closing keynote address I delivered at Structures Congress 2012 • Reform of Structural Engineering Education: We have long
entitled Developing the Next Generation of Structural Engineers. The theme recognized that, to excel in the future, we need structural
resonated with many in the audience, and opportunities started to flow engineering leaders that are more creative, communicative, and
over the transom. Within a few years, I found myself on the board of collaborative. This requires a revolution in SE education.
the SEI Futures Fund, was a founding ExCom member of the new SEI • Bringing Together Practice, Education, and Research: If we are
Global Activities Division, and joined the SEI Board of Governors. I also to have a genuinely innovative, dynamic, and responsive pro-
was drawn into the Institution of Structural Engineers in the UK, where fession where new materials, structural systems, and processes
I currently serve as a Board Trustee. SEI and IStructE have formed a are brought to practice more quickly, we need an integrated
great collaboration; we held our first international structural engineering relationship between practitioners, teachers, and researchers.
conference in Dubai at the end of September. An unexpected bonus of • Collaboration with Like-Minded Organizations: We in SEI
these commitments is that I have developed a network of close profes- cannot accomplish what we need to in a vacuum. The AEC
sional friends around the globe. When the invitation came to stand for industry is vast and siloed. There is a whole world out there
the position of SEI President, I did not hesitate. that we must embrace.
My goal as SEI President will be to help continue our work to prepare I am grateful for the opportunity to serve as your President. In the
structural engineers and the structural engineering profession for a next year, I am committed to engaging with as many of our members
vibrant and sustainable future. Collectively, we have done great work as possible through travel and physical meetings, as well as through
since the publication of the SEI Vision document in 2013. Most notably, all virtual channels available. Please get involved in an SEI Chapter
we have made significant advances in adoption of performance-based or Committee effort. There is much work to be done and many
design, globalization, and collaboration with like-minded professional opportunities. www.asce.org/SEI

Advancing the Profession

Confistructural
Improve dential Reporting on Structural
CROSS-US is a confidential reporting
system that captures and shares lessons

Safety practice which

engineering
learned from structural safety issues
might not otherwise be available
and public safety to the public.
Access free reports on structural safety and sign up for updates at www.cross-us.org.
through learning Anyone is invited to confidentially submit
reports of structural failures, near misses,
from failures and concerns, and incidents, for anonymous

Errata If you
near misses. SEIdevelopment
Standards of Supplements
analysis commentary
andby
subject matter experts, and to use the
Errata including ASCE 7. See www.asce.org/SEI-Errata.
would like to submit errata, contact Jon Esslinger at jesslinger@asce.org.
valuable information posted.

f Learn more www.cross-us.org | www.asce.org/SEI N O V E M B E R 2 019 55

 CASE in Point
Did you know?
CASE has tools and practice guidelines to help firms deal with a wide variety of business scenarios that structural engineering firms face
daily. Whether your firm needs to establish a new Quality Assurance Program, update its risk management program, keep track of the skills
young engineers are learning at each level of experience, or need a sample contract document – CASE has the tools you need!
CASE has several tools available for firms to use to enhance their construction management practices.
CASE #4 – An Agreement Between Client and Structural Engineer for Special Inspection Services
CASE #6 – An Agreement Between Client and Structural Engineer for a Structural Condition
Assessment
CASE #7 – An Agreement for Structural Peer Review Services
CASE #8 – An Agreement Between Client and Structural Engineer for Forensic Engineering
(Expert) Services
CASE #12 – An Agreement Between Structural Engineer of Record (SER) and Contractor for
Transfer of Digital Data or Building Informational Model File
Commentary C – Commentary on AIA Document A201, General Conditions of the Contract for
Construction, 2017 edition
CASE 962-D – A Guideline Addressing Coordination and Completeness of Structural Construction Documents
CASE 962-E – Self-Study Guide for the Performance of Site Visits During Construction
CASE 962-F – A Guideline Addressing the Bidding and Construction Administration Phases for the Structural Engineer
CASE 962-G – Guidelines for Performing Project Specific Peer Reviews on Structural Projects
Tool 2-4 Project Risk Management Plan
Tool 4-3 Sample Correspondence Guidelines
Tool 9-1 A Guideline Addressing Coordination and Completeness of Structural Construction Documents
Tool 10-1 Site Visit Cards
Tool 10-2 Construction Administration Log

CASE Tool 5-1: A Guide to the Practice of Structural Engineering – UPDATED

CASE has updated and released CASE 5-1: A Guide to the Practice of Structural Engineering. This tool is intended to teach structural engi-
neers the business of being a consulting structural engineer and things they may not have learned in college. While the target audience for
this tool is the young engineer with 0 to 3 years of experience, it also serves as a useful reminder for engineers of any age or experience. The
Guide also contains a test at the end of the document to measure how much was learned and retained. Other sections deal with getting and
starting projects, schematic design, design development, construction documents, third party review, contractor selection/project pricing/
delivery methods, construction administration, project accounting and billing, and professional ethics.
Primary updates to 5-1 included adjustments reflecting changes in today’s technology and keeping the document current with best
business practices.

You can purchase these and the other Risk Management Tools at www.acec.org/bookstore.

CASE Winter Member Meeting

SAVE THE DATE!
CASE is revamping their meetings. The design of the meetings will be used to
encourage all members to attend different breakout sessions along with a proj-
ect discussion and a roundtable on unique business practices challenges faced
by structural engineering firms. The 2020 CASE Winter Member Meeting is
scheduled for February 27-20, 2020, in New Orleans, LA. More information
and registration information will be published in December. Questions? Contact
Heather Talbert (htalbert@acec.org).

Follow ACEC Coalitions on Twitter – @ACECCoalitions.

56 STRUCTURE magazine
 News of the Council of American Structural Engineers

CASE Summer Membership Meeting Update

CASE convenes two membership meetings a year for continuing education and networking. Over two dozen CASE members and guests
attended the recent meeting in Atlanta, GA, June 13-14, making this another well attended and productive meeting. During the meeting,
members had the opportunity to hear about the Mercedes-Benz Stadium Structural Design and Delivery from Richard Saunders, S.E., P.E.,
and Matt Breidenthal, P.E., S.E., LEED AP from HOK Atlanta. Linda Bauer Darr, ACEC President and CEO, engaged CASE members
in discussion regarding the future direction for ACEC and Coalitions. CASE members also attended break-out sessions with the CASE
Contracts, Guidelines, Toolkit, and Programs and Communications Committees.
Current initiatives include:
I. Contracts Committee – Chair: Brent Wright (brent@wrighteng.net)
• CASE Commentary A on AIA Document C401 to legal review
• Reviewing CASE Agreements #1 through Agreement #12

II.Guidelines Committee – Chair: Kevin Chamberlain (kevinc@dcstructural.com)

• Structural Engineer’s Guide to Working with a Geotechnical Engineer
• Seismic Engineering Business Practices for the Structural Engineer
• Guideline 962-D: Guideline Addressing Coordination and Completion of Structural Construction Documents

III. Programs and Communications Committee – Chair: Nils Ericson (nericson@m2structural.com)

• Submitted session topics for the 2020 NASCC Steel Conference; AISC liked both and has given us the option of doing both
• Finalized CASE’s three sessions at the 2019 ACEC Fall Conference
• Discussed the option selected for submission for the 2020 SEI Structures Congress
• Discussed schedule changes and speakers/topics for the 2020 CASE Winter Meeting: Thursday night local project highlight,
Friday morning breakfast roundtable, Friday lunch War Story

IV. Toolkit Committee – Chair: Brent White (brentw@arwengineers.com)

• Finished updates to the current tool: Tool 5-1: Guide to the Practice of Structural Engineering
• Finished the following new document: Tool 5-6: Lessons Learned

And the Scholarship Winner Is….

The CASE scholarship, administered by the ACEC College of Fellows, is awarded every year to a deserving student seeking a Master’s degree
in an ABET-accredited engineering program. Since 2010, the CASE Scholarship program has given over $29,000 to engineering students to
help pave their way to a bright future in structural engineering. CASE strives to attract the best and brightest to the structural engineering
profession, and educational support is the best way we can ensure the future of our profession.
The 2019 winner, Tyler Wilfong, will graduate in May 2020 with a Master’s Degree in Structural Engineering from California State
University, Fresno.

Manual for New Consulting Engineers

An HR Favorite for New Hires
ACEC’s best-seller, “Can I Borrow Your Watch?” A Beginner’s Guide to Succeeding in a Professional Consulting
Organization offers new engineers a head start in the business of professional consulting. This essential guide is tailored
to the unique needs of engineering firms, and the skills and experiences rookie consultants need to be successful in a
large organization, including:
• Proposal Preparation • Financial Management • Client Relationships
• Project Management • Staff Management
With over 140 pages of consulting expertise, this resource is the perfect addition to any new staffer’s welcome pack or in-house orientation.
It can even be a useful resource for more seasoned engineers looking to refine their skills. To order this book, go to www.acec.org/bookstore.
Bulk ordering is available; for more information, contact Maureen Brown (mbrown@acec.org).

N O V E M B E R 2 019 57
 SOFTWARE updates
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Meca Enterprises, Inc
CADRE Analytic Phone: 918-258-2913
Phone: 425-392-4309 Web: www.mecaenterprises.com
Web: www.cadreanalytic.com Product: MecaStack
Product: CADRE Pro 6.9 Description: Design of steel cylindrical stacks. Allows Trimble
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Loading conditions include discrete, pressure, or guy wired supported steel stack. Provides a 3-D Web: www.tekla.com/us
hydrostatic, seismic, and dynamic response. Features graphical representation of the stack being analyzed and Product: Tekla Tedds
for presenting, displaying, plotting, and tabulating handles many common design codes used to design Description: Automates repetitive and error
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Product: QuickQnect
Dlubal Software, Inc. Product: Tekla Structural Designer
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and steel design, Tekla Structural Designer
Product: RFEM, RWIND Simulation savings. In minutes, users can connect most steel
helps engineering businesses win more projects
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Integrate resulting wind pressures into the Preference Optimization and Bolt Optimization.
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on specialty structures is now possible with Web: risa.com
RWIND Simulation. Product: RISAFloor Victaulic
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constructed of steel (composite and noncomposite), Web: www.victaulicsoftware.com
open web steel joists, cold-formed steel, as well as Product: Victaulic Tools for Revit® 2020
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ENERCALC 3D.

58 STRUCTURE magazine
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