Pre Engineered Buildings http://www.engineeringcivil.com/pre-engineered-buildings.

Introduction to Pre Engineered Buildings

Technological improvement over the year has contributed immensely to the enhancement of quality of life through various new products and
services. One such revolution was the pre engineered buildings. Through its origin can be traced back to 1960’s its potential has been felt only during
the recent years. This was mainly due to the development in technology, which helped in computerizing the design and design.

Though initially only off the shelf products were available in these configurations aided by the technological development tailor made solutions are
also made using this technology in very short durations. A recent survey by the Metal Building Associations (MBMA) shows that about 60% of the
non residential low rises building in USA are pre engineered buildings.

Although PEB systems are extensively used in industrial and many other non residential constructions world wide, it is relatively a new concept in
India. These concepts were introduced to the Indian markets lately in the late 1990’s with the opening up of the economy and a number of multi
nationals setting up their projects.The market potential of PEB’s is 1.2 million tones per annum. The current pre engineered steel building
manufacturing capacity is 0.35 million tones per annum. The industry is growing at the compound rate of 25 to 30 %.

With respect to design of the structure and aesthetic appearance India is way behind. Indian manufacturers are trying to catch up; comparatively
PEB’s is a new concept in India. Beside, in fabrication and other areas of PEB India is very good. As compared to other countries Indian codes for
building design are stringent but safer. IS standards are upgraded continuously. In India, American codes are also followed.

Pre engineered steel buildings can be fitted with different structural accessories including
mezzanine floors, canopies, fascias, interior partitions etc. and the building is made water proof
by use of special mastic beads, filler strips and trims. This is very versatile buildings systems and
can be finished internally to serve any functions and accessorized externally to achieve attractive
and unique designing styles. It is very advantageous over the conventional buildings and is really
helpful in the low rise building design.

Pre engineered buildings are generally low rise buildings however the maximum eave height can
go upto 25 to 30 metres. Low rise buildings are ideal for offices, houses, showrooms, shop fronts
etc. The application of pre engineered buildings concept to low rise buildings is very economical
and speedy. Buildings can be constructed in less than half the normal time especially when
complemented with the other engineered sub systems.

The most common and economical type of low rise buildings is a building with ground floor and
two intermediate floor plus roof. The roof of low rise buildings may be flat or sloped.
Intermediate floors of low rise buildings are made of mezzanine systems. Single storied houses
for living take minimum time for construction and can be built in any type of geographical
location like extreme cold hilly areas, high rain prone areas, plain land obviously and extreme hot
climatic zones as well.

Applications of Pre Engineered Buildings (PEB)

1. WAREHOUSES

2. FACTORIES

3. WORKSHOPS

4. OFFICES

5. GAS STATIONS

6. VEHICLE PARKING SHEDS

7. SHOWROOMS

8. AIRCRAFT HANGARS

9. METRO STATIONS

10. SCHOOLS

11. RECREATIONAL

12. INDOOR STADIUM ROOFS

13. OUTDOOR STADIUM CANOPIES

14. BRIDGES

15. RAILWAY PLATFORM SHELTERS

Advantages of Pre Engineered Buildings

REDUCED CONSTRUCTION TIME: Buildings are typically delivered in just a few weeks after approval of drawings. Foundation and anchor
bolts are cast parallel with finished, ready for the site bolting. Our study shows that in India the use of PEB will reduce total construction time of the
project by at least 50%. This also allows faster occupancy and earlier realization of revenue.

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LOWER COST: Due to the systems approach, there is a significant saving in design, manufacturing and on site erection cost. The secondary members
and cladding nest together reducing transportation cost.

FLEXIBILTY OF EXPANSION: Buildings can be easily expanded in length by adding additional bays. Also expansion in width and height is
possible by pre designing for future expansion.

LARGE CLEAR SPANS: Buildings can be supplied to around 80M clear spans.

QUALITY CONTROL: As buildings are manufactured completely in the factory under controlled conditions the quality is assured.

LOW MAINTENANCE : Buildings are supplied with high quality paint systems for cladding and steel to suit ambient conditions at the site, which
results in long durability and low maintenance coats.

ENERGY EFFICIENT ROOFING AND WALL SYSTEMS: Buildings can be supplied with polyurethane insulated panels or fiberglass blankets
insulation to achieve required “U” values.

ARCHITECTURAL VERSTALITY: Building can be supplied with various types of fascias, canopies, and curved eaves and are designed to receive
pre cast concrete wall panels, curtain walls, block walls and other wall systems.

SINGLE SOURCE RESPONSIBILTY: As the complete building package is supplied by a single vendor, compatibility of all the building components
and accessories is assured. This is one of the major benefits of the pre engineered building systems.

Pre Engineered Buildings Vs Conventional Steel Buildings

PROPERTY PEB BUILDINGS CONVENTIONAL STEEL

BUILDINGS

STRUCTURE WEIGHT Pre engineered buildings are on Primary steel members are
the average 30% lighter because selected hot rolled “T” sections.
of the efficient use of steel. Which are, in many segments of
Primary framing members are the members heavier than what is
tapered built up section. With the actually required by design?
large depths in areas of higher Members have constant cross
stress. section regardless of the varying
magnitude of the local stresses
along the member length.

Secondary members are light Secondary members are selected

weight roll formed “Z” or “C” from standard hot rolled sections
shaped members. which are much heavier.

DESIGN Quick and efficient: since PEB’s Each conventional steel structure
are mainly formed by standard is designed form scratch with
sections and connections design, fewer design aids available to the
time is significantly reduced. engineer.
Basic design based on

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international design codes are

used over and over.

Specialized computer analysis Substantial engineering and

design programs optimize detailing work is required from
material required. Drafting is also the very basic is required by the
computerized using standard consultant with fewer design
detail that minimize the use of aids.
project custom details.

Design shop detail sketches and Extensive amount of consultant

erection drawings are supplied time is devoted to the alterations
free of cost by the manufacturer. that have to be done.
Approval drawing is usually
prepared within in 2 weeks.

PEB designers design and detail As each project is a new project

PEB buildings almost every day engineers need more time to
of the year resulting in improving develop the designs and details of
the quality of designs every time the unique structure.
they work

DELIEVERY Average 6 to 8 weeks Average 20 to 26 weeks

FOUNDATIONS Simple design, easy to construct Extensive, heavy foundation

and light weight. required.

ERECTION SIMPLICITY Since the connection of The connections are normally

compounds is standard the complicated and differ from
learning curve of erection for project to project resulting tin
each subsequent project is faster. increasing the time for erection
of the buildings.

Periodic free of charge erection There has to be separate

is provided at the site by the allocation of labour for the
manufacturer. purpose of erection.

ERECTION COST AND TIME Both costs and time of erection Typically, conventional steel
are accurately known based upon buildings are 20% more
extensive experience with similar expensive than PEB in most of
buildings. the cases, the erection costs and
time are not estimated accurately.

The erection process is faster and Erection process is slow and

much easier with very less extensive field labour is required.
requirement for equipment. Heavy equipment is also needed.

SEISMIC RESISTANCE The low weight flexible frames Rigid heavy frames do not
offer higher resistance to seismic perform well in seismic zones.
forces.

OVER ALL PRICE Price per square meter may be as Higher price per square meter.
low as by 30 % than the
conventional building.

ARCHITECTURE Outstanding architectural design Special architectural design and

can be achieved at low cost using features must be developed for
standard architectural details and each project which often require
interfaces. research and thus resulting in
higher cost.

SOURCING AND Building is supplied complete Many sources of supply are there

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COORDINATION with all accessories including so it becomes difficult to co

erection for a single “ONE STOP ordinate and handle the things.
SOURCE”.

COST OF CHARGE ORDER PEB manufactures usually stock Substitution of hot rolled sections
a large amount of that can be infrequently rolled by mills is
flexibly used in many types of expensive and time consuming.
PEB projects.

Change orders are easily Change orders that are made

accommodated at all stages of after the dispatch of hot rolled
the order fulfillment process. sections result in increasing the
Little or no material is wasted time and cost involved in the
even if a change order is made project.
after fabrication starts.

BUILDING ACCESSORIES Designed to fit the system with Every project requires different
standardized and inter and special design fro accessories
changeable parts. Including pre and special sourcing for each
designed flashing and trims. item. Flashing and trims must be
Building accessories are mass uniquely designed and fabricated.
produced for economy and are
available with the building.

FUTURE EXPANSIONS All project records are safely and It would be difficult to obtain
orderly kept in electronic format project records after a long
which make sit easy for the period of time. It is required to
owner to obtain a copy of his contact more than one number of
building record at any time. parties.

Future expansion is very easy Future expansion is most tedious

and simple. and more costly.

SAFETY AND RESPONSIBILTY Single source of responsibility is Multiple responsibilities can

there because all the job is being result in question of who is
done by one supplier. responsible when the components
do not fit in properly, insufficient
material is supplied or parts fail
to perform particularly at the
supplier/contractor interface.

PERFORMANCE All components have been Components are custom designed

specified and designed specially for a specific application on a
to act together as a system for specific job. Design and detailing
maximum efficiency, precise fir errors are possible when
and peak performance in the assembling the diverse
field. components into unique
buildings.

Experience with similar Each building design is unique,

buildings, in actual field so predication, of how
conditions world wide, has components will perform
resulted in design improvements together is uncertain. Materials
over time, which allow which have performed well in
dependable prediction of some climates may not do well in
performance. other conditions.

Design of Pre Engineered Buildings (PEB)

The main framing of PEB systems is analyzed by the stiffness matrix method. The design is based on allowable stress design (ASD) as per the
American institute of Steel Construction specification or the IS 800. the design program provides an economic and efficient design of the main frames
and allows the user to utilize the program in different modes to produce the frame design geometry and loading and the desired load combinations as
specified by the building code opted by the user. The program operates through the maximum number of cycles specified to arrive at an acceptable
design. The program

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uses the stiffness matrix method to arrive at an acceptable design. The program uses the stiffness matrix method to arrive at the solution of
displacements and forces. The strain energy method is adopted to calculate the fixed end moments, stiffness and carry over factors. Numerical
integration is used.

Design Cycle

The design cycle consists of the following steps:

1. Set up section sizes and brace locations based on the geometry and loading specified for the frame design.

2. Calculate moment, shear, and axial force at each analysis point for each load combination.

3. Compute allowable shear, allowable axial and allowable bending stress in compression and tension at each analysis point.

4. Compute the corresponding stress ratios for shear, axial and bending based on the actual and allowable stresses and calculate the combined stress
ratios.

5. Design the optimum splice location and check to see whether the predicted sizes confirm to manufacturing constraints.

6. Using the web optimization mode, arrive at the optimum web depths for the next cycle and update the member data file.

7. At the end of all design cycles, an analysis is run to achieve flange brace optimization.
Frame Geometry
The program has the capability to handle different types of frame geometry as follows
Frames of different types viz. rigid frames, frames with multiple internal columns, single slope frames, lean to frames etc. Frames with varying spans,
varying heights and varying slopes etc.
Frames with different types of supports viz. pinned supports, fixed supports, sinking supports, supports with some degrees of freedom released.
Unsymmetrical frames with off centric, unequal modules, varying slopes etc.
User specified purlin and girt spacing and flange brace location.
Frame Loading
Frame design can handle different types of loadings as described below:
All the building dead loads due to sheeting, purlins, etc. and the self weight of the frame. Imposed live load on the frame with tributary reductions as
well.
Collateral load such as false ceiling, light fixtures, AC ducting loads, sprinkler systems and many other suspended loads of similar nature.

Wind loads input such as basic wind speed or basic wind pressure that will be converted to deign wind pressure as per the building code specified by the
user and shall be applied to the different members of the building according to the coefficients mentioned in the codes prescribed by the user.
The

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standard building codes like MBMA, UBC, ANSI, IS:875 part 3 etc are used fro this purpose.
Crane and non crane loading can be specified by the user and the program has the capability to handle these special loads and combine them with
the other loads as required.
Seismic loads corresponding to the different zone categories of various international codes can also be defined and combined with other load cases as
required.Temperature loads can also be specified in the form of different differential temperature value on centigrade and specifying the appropriate
coefficient for the thermal expansion.Load combinations with appropriate load factors can be specified by the user as desired.

Design Codes

Following are the main design codes generally

used: AISC : American institute of steel

construction manual AISI : American iron and steel

institute specifications MBMA : Metal building

manufacturer’s code

ANSI : American national standards institute specifications

ASCE : American society of civil engineers

UBC : Uniform building

code IS : Indian

standards

Design Criteria

DESIGN METHOD: Allowable stress design method is used as per the AISC specifications.

DEFLECTIONS: Unless otherwise specified, the deflections will go to MBMA, AISC criteria and standard industry

practices. PRIMARY FRAMING: Moment resisting frames with pinned or fixed bases.

SECONDARY FRAMING: Cold formed Z sections or C sections for purlins or girts designed as continuous beams spanning over rafters and columns
with laps.

LONGITUDANAL STABILITY: Wind load on building end walls is transferred through roof purlins to braced bays and carried to the foundations
through diagonal bracing.

DESIGN SOFTWARE

The latest software that is used for design is STAAD 2007.

DESIGN PROCESS

The frame data is assembled based on number of frame members, number of joints, number of degrees of freedom, the conditions of restraint and the
elastic properties of the members. Based on this, the data is stored and member section properties are computed. The overall joint stiffness matrix is
obtained based on the above frame data by summation of individual stiffness matrices considering all possible displacements. The load vector is then
generated based on the loading data and the unknown displacements are obtained by inverting the overall joint stiffness matrix and multiplying with
the load vector.

Knowing the free joint

displacements REPORT ON

PLANT VISIT DEPARTMENTS

IN THE PLANT

PRODUCTION, PLANNING & CONTROL (PPC)

SHEARING

BUILT

UP

FINISHI

NG

COLD

FORM

SHIPPIN
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G

QUALITY CONTROL
Pre Engineered Buildings http://www.engineeringcivil.com/pre-engineered-buildings.h

MAINTENANCE (ELECTRICAL)

MAINTENANCE

(MECHANICAL)

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PRODUCTION, PLANNING & CONTROL

The PPC department in our plant is headed over by Mr. C.M.PANDE. The PPC department can be called to be the controller of all the other
departments of our plant because it keeps a check on at what point of time what kind of work and how much work according to the manpower
available is to be given to a particular department. They also plan the releases as to how much tonnage is to be released on any given data. They
also keep a proper record on daily, weekly, monthly basis that how much work is being done by which department and is it fulfilling the criteria or
not so as to ensure proper meeting up of the targets assigned. We also got to know about the manufacturing processes that how they take place in a
sequent manner in our plant. They also made us aware of the system that how a BOQ and drawings travels from the head office to the plant and then
the work is actually distributed among the departments in the plant. The PPC department is using nesting software to prepare proper part marks for eg.
We get HR plates in a standard width of 1500 mm so nesting software tells us that what sized plates should be cut from that so as to minimize the
scrap, this job is also done by the PPC and is known as part marking. The entire job in the plant is done according to these part marks only. Also the
job of maintaining the inventory of raw materials is done by the PPC department i.e. it has to keep a check on the quantity of raw materials available
and has to ensure that sufficient quantity of material is always available. Also it has to take care of the transport availability for dispatching the
materials. PPC department works in co ordination with the every department like with accounts department.

This informational post has been submitted to us by Er Gursharan Singh and then modified by Er Kanwarjot Singh. To see the presentation of the same
click here.

Presentation On Pre Engineered Steel Buildings

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