Integration of Design and Construction of the Tallest Building in

Korea, Tower Palace III, Seoul, Korea

A.K. Abdelrazaq1, W. F. Baker2, K.R. Chung3, J. Pawlikowski4, Insoo Wang 5, K.S. Yom6
1
Executive Director, Samsung Corporation, Engineering and Construction Group
2
Partner, 4Associate, Skidmore, Owings & Merrill LLP, Chicago, USA
3
Principal, Dong Yang Structural Engineering Co., Ltd, Seoul, Korea
4
Vice President, 5Manager, Samsung Corporation, Construction & Engineering Group

Abstract
Tower Palace III was conceived as a 93-story residential tower soaring 320 meters into Seouls skyline. However,
concerns of the local residents and authorities over the building height resulted in a 73-story tower with the same
gross floor area. The early integration of aerodynamic shaping and wind engineering considerations played a major
role in the architectural massing and design of the tower. The Contractors input in selecting the optimum
structural system resulted in a cost effective tower that served the clients needs and the tower was completed ahead
of schedule. This paper presents a brief overview of the structural system development of the tower and its direct
integration with the construction aspects, discusses the construction planning of the key structural components of
the tower, and briefly describes the monitoring program incorporated into the tower for the evaluation of time
dependent deformation.
Keywords: indirect outrigger belt-wall system, composite column instrumentation, self compacting/consolidating concrete, mat
foundation, wind engineering integration with the architectural massing.

1. Introduction
Tower Palace III was part of Samsung Life
Insurance Togok site development plan, which is
located in the Kangnam district of Seoul, South Korea
and consisted of three phases. Phases I and II included
Tower Palace I and II development that comprised of
six high-rise residential towers varying from 42 to 66
stories. Phase III of this development, Tower Palace
III (TPIII), consisted of a 73-story single point tower
with an adjacent eight (8) story sport center, and six
(6) levels of parking below grade.

Tower Palace III site development is located in a

moderate wind climate and subject to moderate/low
seismic forces. Early planning and concept envisioned
this tower to be 320 meters high and an all-residential
building. The critical design criteria for this very tall
luxury residential tower called for controlling the
dynamic response of the tower and managing its wind
engineering aspects. During the design process, the
Figure 1: Tower Palace Development
building evolved into three different schemes, where
each of the schemes was accepted by the client and studies indicated that the tower massing, exterior wall
fully studied at the Boundary Layer Wind Tunnel treatment, and the dynamic building characteristics
Laboratory (BLWTL), See Figure 2. Force balance resulted in a structure that was not sensitive to
dynamic wind excitations, and the predicted building
Ahmad Abdelrazaq, Vice President / Executive Director acceleration and torsional velocities were below the
Samsung Corporation, Engineering & Construction Group internationally acceptable acceleration and torsional
12 flr Samsung Plaza bldg. 263Seohyun, Bundang-Gu, velocity criteria.
Sungnam-Gu Gyonggi-Do, Korea 463-721 While the three schemes had the same gross floor
Tel: 82.2.2145.5190; Fax: 82.2.2145.5770, area and approximately the same number of apartment
E-mail, Ahmad.abdelrazaq1@samsung.com units, the 93-story tower was not accepted by the

654 CTBUH 2004 October 10~13, Seoul, Korea

neighbors due to its height and the potential for traffic Structural System Design Approach
congestion in the area. The 73-story tower, scheme 3, The structural design process of the tower was
was finally selected by the client to satisfy the formulated based on the following goals:
concerns of the local authorities and the neighbors.
Optimize the tower structural system for strength,
stiffness, cost effectiveness, redundancy, and speed
of construction.
Manage and locate the gravity load resisting system
so as to maximize its use in resisting the lateral
loads while harmonizing with the architectural
planning of a luxury residential tower.
Incorporate the latest innovations in analysis,
design, materials, and construction methods.
Limit the building drift, acceleration, and torsional
velocity to within the international accepted design
criteria.
Control the relative displacement between the
vertical members, especially for composite
buildings.
Control the dynamic response of the tower under
wind loading by tuning the structural characteristics
of the building to improve its dynamic behavior and
a) 93-Story (320m) b) 77-Story (270m) c) 73-Story (264m)
to prevent lock-in vibration due to the vortex
Scheme 1 Scheme 2 Scheme 3
shedding. Favorable dynamic behavior of the
Figure 2: Tower Palace III Massing Studies tower was achieved by:

This paper presents an overview of the a) Varying the building shape along the height
development of the towers structural system and its while continuing, without interruption, the
direct integration with the architectural massing and building gravity and lateral load resisting
construction planning for the key structural system;
components of the tower. In addition, this paper b) reducing the floor plan along the buildings
briefly discusses the instrumentation of the tower to upper zone; and
evaluate the long term behavior of the composite c) creating irregularities along the buildings
columns and the reinforced concrete core wall. The exterior surfaces, thus reducing the local
strain measurements at the composite columns and the cladding pressures as well as the overall
core wall correlated well with the predicted strains. wind loads on the building structure.

2. Structural System Design Approach Wind Engineering

Wind loads considered in the analysis of the tower
structure were developed using the code defined load
criteria as well as the results from the wind tunnel
testing program, which is based on historical
climatological data. The wind tunnel testing program,
conducted at the Boundary Layer Wind Tunnel
Laboratory (BLWTL) included 1) site proximity wind
analysis model, 2) force balance tests, see Figure 3,
conducted for all schemes, 3) cladding and pressure
integration test, and 4) pedestrian wind studies.
The climatological study performed for the project
was determined for a 100 year return period with a
mean-hourly gradient wind speed of 41 m/s. This
resulted in a wind pressure of 2.5kN/m2. Strength
design of the tower was based on both the code-
prescribed wind loads with exposure A and the wind
93 Story Tower 77 story Tower 73 story Tower tunnel developed 100-year return period. Wind tunnel
recommendation included combining the wind loads in
Figure 3: Wind Tunnel Test Models

CTBUH 2004 October 10~13, Seoul, Korea 655

the orthogonal direction and torsional moments A 3-dimensional finite elements analysis model,
simultaneously. 1.5% and 2% damping were assumed using FLAC 3D, was utilized to model the entire rock
for serviceability and strength design respectively. mass/foundation mat in order to better estimate the
foundation settlement and behavior. See figure 4.
Seismic Considerations
Two FLAC3D foundation analysis models were
TPIII is located in an area with low seismic
performed to evaluate the impact of the faults on the
activity and the building is essentially founded on rock
settlement analysis. Comparison of the analysis results
foundation with locally fractured and weak layers of
between the two models indicated that the overall
rocks. The seismic behavior and response of the tower
building settlement was increased by approximately
was evaluated using the modal response spectrum
23% due to the presence of the faults.
analysis method. Response spectrum curves and
loading conditions required by the Korean Building
Because of the variation of the rock quality, the
Law were utilized as a base for the seismic loading
presence of faults, and the shape of the
conditions. Since the building is very tall and flexible,
building/structure, it was prudent to utilize a mat
the tower was controlled by wind design rather than
foundation system under the tower footprint in order to
seismic design except at the top of the building, where
minimize the differential settlement, reduce the impact
the whip lash effects generated forces that are slightly
of the differential settlement on the superstructure
higher than the wind forces. The overall building drift
member design, and to bridge over the local weak rock
and interstory drift met the Korean and UBC 97
layers and pockets. Based on the 3DFLAC settlement
building code requirements.
analysis model, Dames & Moore provided the soil
stiffness that was utilized as a basis for soil-structure
analysis model of the tower.

Figure 4: FLAC3D- Foundation Analysis model

(Courtesy of Dames & Moore) Figure 5: Soil Structure Interaction Analysis Model

Foundation System Considerations

The tower superstructure is founded on a 3500 The mat foundation analysis indicated that the
mm high performance reinforced concrete mat over maximum anticipated settlement under the tower
lean concrete slab over prepared rock. The rock would be approximately 15mm. The building survey
quality and mechanical characteristics varied over the indicated that the actual foundation settlement was
site in general and in particular at the footprint of the smaller than anticipated.
tower due to the presence of ancient faults and shear
zones. These faults/shear zones started at Differential Axial Shortening Considerations
approximately 7 meters north of the foundation mat to While optimizing the lateral load resisting system
approximately 150 meters below the south edge of the of the tower, minimizing the differential shortening,
foundation mat. The presence of these fault caused between the composite columns and the core wall, was
concerns about the behavior of the foundation system. one of the critical issues considered during the
The geotechnical engineering work, performed by development of the structural system of the tower.
Dames and Moore, San Francisco, CA, USA, indicated
that these faults are inactive.

656 CTBUH 2004 October 10~13, Seoul, Korea

 55 Belt Wall

Exterior
Columns
Exterior R/C Core
Columns Wall System
16 Belt Wall
Interior Composite
Columns Floor Framing
Core Wall
Mat
Foundation

a) Structural System Diagram b) Floor Framing Plan

Figure 5: Structural System Diagram & Typical Floor Framing Plan

3. Structural System Description components, which included the belt wall and the floor
slabs.
Floor Framing System
Several Floor framing system were considered for The core wall system
the tower, including a flat plate system and composite While the exterior flanges of the core wall vary in
steel framing. However, because of the client thickness from 550 mm at the bottom to 400 mm at the
marketing requirements, a composite floor framing top, the interior core wall web thicknesses were
system was selected. The composite floor framing maintained at 300mm throughout the building height.
system consisted of a 150mm composite metal deck In a typical level, the core wall vertical wall
slab spanning 3 to 4 meters between 400mm deep hot components are rigidly connected by a series of
rolled composite steel beams, see Figure 5. The 750mm deep composite or reinforced concrete link
400mm beam depth was selected to allow for MEP beams. The link beam widths typically match the
openings so that the ceiling sandwich is minimized. adjacent core wall thicknesses.
The composite structural steel beams were arranged to
reduce the number of embedded plates into the core
wall and were fireproofed with cementitious material
to achieve the applicable fire rating.

Lateral Load Resisting System

The lateral load resisting system of the tower
provided resistance to wind and seismic forces and
consisted of a high performance, reinforced concrete
core wall system, from the foundation to the roof that
was linked to the exterior composite columns by an
indirect outrigger belt wall system at the mechanical
levels (16 to 17, and 55 to 56). The interaction of the
core wall system and the exterior columns was
provided through deformation compatibility, resulting
in significant forces in the belt wall system Figure 6: Composite Link Beam Details

CTBUH 2004 October 10~13, Seoul, Korea 657

 Figure 7: Belt wall system load flow diagram between the core wall and the exterior belt wall system

Due to the link beam depth limitations, a core walls throughout the building life, and during the
composite structural steel beam was introduced at the construction period.
locations where large shear and bending moment
forces existed. See Figure 6. The composite link The indirect outrigger belt wall system
beam consisted of a built-up wide flanged structural The indirect outrigger belt wall system is
steel beam or a single structural steel plate that were essentially similar to an outrigger wall system;
embedded in the concrete section. The structural steel however, the mechanism of force resolution between
web section, where required, was designed to resist the the core wall and the belt wall system is indirect,
majority of the shear forces and the composite section through the floor slabs rather than the direct wall
was utilized in resisting the bending moments. Since connection. The indirect outrigger belt wall system
the composite link beam section provides significant consists of an exterior reinforced concrete perimeter
shear ductility, the bending moment forces in the link wall that rigidly connects the exterior composite
beams can be limited. Thus the maximum forces that columns and the very stiff floor slabs.
the core wall system can attract in a seismic event can
The indirect outrigger belt walls for TPIII were
be managed, and the overall building behavior can be
located at the mechanical levels (16 and 55) and
controlled without significant damage even in severe
consisted of an 800mm wide by 8 meter high wall
seismic event.
perimeter wall and a 300mm thick floor slabs, at the
top and the bottom of the perimeter walls. While the
The exterior columns
high perimeter belt wall bending and shear stiffness
The exterior columns of the tower are typically
connected the exterior composite columns rigidly, the
steel reinforced concrete columns (SRCC) that vary
floor slab high in-plane bending and shear stiffness
from 1350mm Diameter at subgrade levels, to a
forced deformation compatibility and shear force
maximum of 1000x1000 from levels 4 to 56, to
redistribution between the core wall and the exterior
900x900 from level 57 to 65, to 800x800 from the 66
belt wall frame system.
level to the roof. In order to minimize the column size,
concrete filled (CFT) with high strength concrete was Since the perimeter belt walls reduced the relative
considered for the exterior and interior columns at the displacements between floors, the lateral system
conceptual design stage. However, SRC columns were rotations at the belt wall levels were significantly
adopted instead, in order to minimize the differential reduced, and thus reducing the building lateral
relative movement, due to immediate and long term displacement significantly. The restraining effects of
deformations, between the exterior columns and the the exterior columns against the belt wall rotation
resulted in axial loads in the exterior columns. These

658 CTBUH 2004 October 10~13, Seoul, Korea

axial forces were counter balanced by force couples saving in casting time by placing the mat in a
into the belt wall system, which were then counter single pour and within 12-hours;
balanced by force couples into the slabs that are finally reduction of labor force;
resisted by the interior core wall system. consistent concrete quality and uniformity,
The advantages of the indirect outrigger belt wall especially in areas with high rebar congestion.
system over a more conventional direct outrigger wall Increasing the concrete bond to rebar due to the
system can be summarized as follows: elimination of bleeding under rebar;
reduction of concrete bleeding;
Placement of the belt wall system at the perimeter eliminating the vibration noise.
did not restrict the mechanical floor space and
allowed for freedom in placing the mechanical
equipment in the plant space, thus reducing the
amount of coordination work required between
trades.
The Construction of the belt wall system was not
in the construction schedule critical path;
The belt system did not have a direct link between
the core wall and the exterior columns, and
therefore eliminated one of the most difficult
technical problems encountered in the design and
detailing of the direct outrigger wall systems,
which is the potential of generating large forces
due to the differential movement between the core
wall and the exterior columns; and Figure 8: Casting the foundation mat
The extensive detailing and construction sequence
work required for the direct outrigger wall system A cooling pipe system was suggested by the
is significantly reduced. contractor to control the heat of hydration for the
massive mat concrete pour and to reduce the curing
4. Construction Planning time. The curing time was reduced from 45 days to 15
days and the maximum temperature at the center of the
Samsung Construction was involved with the mat was reduced from 93oC to 82oC. The maximum
design team from the early design stage in evaluating differential temperature between any two points within
all building systems (structural, architectural, building the mat was less than 20 oC.
services, etc.). Alternate systems and details were
discussed and incorporated in the construction
documents. In addition, the General Contractor issued 90
Hydration Analysis
A
B
a detailed construction and design schedule that was 80 B
C
C

utilized by the design team as a base for providing the 70

Temperature ( C)

necessary documents on time so that the General 60 A

Contractor could proceed early in the construction 50

o

ambient+20 C
planning and work. The core and shell of the 73 story 40

tower and the six (6) subgrade levels were completed 30

ambient
in approximately 18 months. The entire project was 20

completed in 28 months, including the residential fit- 10

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
out space and finishing work. A 3-day cycle was Time (days)

utilized for the tower superstructure and all subsequent 1 00

Actual Temperature
construction activities. 90

80
C enter
70
Tem perture ()

Mat Foundation Construction 60 T op 0. 5m from top

The tower is founded on 3500mm thick, 40Mpa 50

reinforced concrete mat. The mat foundation system 40

30
a m b ient

required significant planning effort while preparing for 20

the 8000 cubic meter pour of high performance 10

20H 52H 96H 139H 163H 177H 240H

concrete. See Figure 8. The General Contractor used 0

0 24 48 72 96 12 0 14 4 16 8 192 216 2 40
self-compacting self-consolidating concrete (SCC) for T im e (h)

the mat foundation. The advantages of using SCC Figure 9: Hydration analysis and measurement
included:

CTBUH 2004 October 10~13, Seoul, Korea 659

 The cooling pipe system consisted of 25mm
stainless steel coils that were spaced vertically at
750mm on center, and horizontally at approximately
1500mm on center, at 128 locations. , The water flow
rate in the cooling pipe system was limited 18
liters/min. The cooling pipes were connected to a
central cooling tower, located at the job site, which
was used to temper the water. The water entered the
cooling pipe system at 34oC, existed at 47oC.
Comparison between the predicted and the actual
temperature of the mat, due to heat generated by the Steel Erection
hydration process, confirmed that the predicted heat of Tier N
Plumbing
Bolting,
hydration analysis results were consistent with the W ldi
actual temperature of the mat. Thus testifying to the
already established analysis procedures utilized for Decking
predicting the heat of hydration of mass concrete. N-1 Stopper
Stud Bolt
Core Wall Construction
Figures 10 and 12 depict the construction MEP work
sequence of the tower and shows that the reinforced N-2 Reinforcing
Conc casting
concrete core wall is constructed at four (4) floors
ahead of the structural steel framing. The core wall
and the structural steel construction is followed by the N-3
Curtain wall
Fire proofing
composite deck placement, the floor slab concrete
pouring, the MEP system installation, and finally the
exterior cladding system installation. The central core
wall construction utilized a climbing formwork system Figure 10: Tower Construction Sequence
designed and provided by Doka (DOKA SKE 100).
shrinkage effects, because of the restraining effects of
Structural Steel Erection and Floor Framing the core wall and the exterior belt wall system.
The structural steel erection of the tower was
divided into 3 wings. In order to reduce the structural Major Equipment
steel erection time and to improve the construction Three (3) self climbing cranes, supported directly
cycle, all the steel columns were erected as four story by the core wall, were utilized for the tower
tiers, and the five (5) different balcony framing around construction. Two concrete pumps (one for
the perimeter of the building were prefabricated and emergency) were available at the site and were used
erected as single units. This erection sequence reduced for concrete placement. All concrete was pumped
the number of pieces handled at the site. Each tier from the ground level to approximately 264m above
consisted of four (4) floors and all the structural steel the ground.
in these floors were erected in 12 days, thus resulting
in 3-day cycle. The concrete slab, at a typical floor,
5. Axial Shortening of the Tower
was divided into 3 equal pours, one for each wing.

Belt Wall Construction One of the key issues considered during the
Because of the complex behavior of the belt wall development of the structural system of the tower was
system, the size of the concrete pour, and the geometry the differential shortening between the core wall and
of the tower, the project called for special detailing, the exterior/interior composite columns during
construction sequence, and construction planning construction and after significant completion time of
effort. Discussion between the General Contractor and the project. The complex behavior of the composite
the design team resulted in eliminating the belt wall columns called for special considerations in
construction sequence from the construction schedule calculating the elastic and long term deformation for
critical path. Construction sequence analysis of the the core wall and the exterior columns. The axial
tower was performed and its impact on the building shortening of the building was done using the state of
design was incorporated into the design process. the art ACI 209 committee draft report for predicting
While the belt wall system was cast in two separate the creep, shrinkage and temperature effects of
pours, the floor slabs were cast in three different pours reinforced concrete structures. This draft report is
at each floor in order to eliminate the potential for based the Gardner-Lockman GL2000 Model, which is
axial load cracking in the slabs, resulting from based on RILEM base of test data.

660 CTBUH 2004 October 10~13, Seoul, Korea

 The predicted composite columns and core wall At TPIII, several high frequency strain gages were
axial shortening by the new analysis program were installed at several SRC columns and at two locations
compared to the actual in-situ strain measurements at in the core wall at several floors. These strain gages
TPIII, and was found to correlate well, thus testifying were connected to a single data logger from which the
to the accuracy of the new analysis models and information has been down loaded automatically for
approach in predicting the time dependent deformation processing by the researchers and the design team.
for axially loaded members. See Figures 11 for
In addition to the in-situ elastic and inelastic time
comparison of the predicted strain to the actual
dependent deformation monitoring programs, a
measured strain.
monitoring program has been installed to monitor the
building dynamic response to dynamic excitations,
especially as it relates to wind effects. It is anticipated
that the instrumentation programs will be expanded
and integrated into a single system that could
essentially provides a health monitoring program to the
building structure, which could finally be integrated
with the permanent intelligent building system.

Figure 11: Measured vs. predicted strains at a

typical Interior composite column

Figure 12: Measured vs. predicted strain at

reinforced concrete core wall
A compensation program was developed to make
up for the overall building shortening and the Figure 12: In progress construction of the tower
differential shortening between the columns and the showing the construction methods of the tower.
core wall. The building shortening was calculated to
be between 270mm to 300mm for the core wall and 6. Conclusion
the exterior columns respectively. However, the
maximum differential shortening, at level 60, between This paper provided a brief overview of some of
the columns and the core wall was estimated to be the issues considered in developing the structural
40mm, at the completion of the building, and 20mm systems and construction planning of Tower Palace III,
after 20 years. Therefore, the column elevations were the tallest building in Korea. The monitoring
adjusted during construction for 20mm so the relative programs incorporated into the design of the tower are
movement between the core wall and the columns very unique, could provide invaluable information and
would be limited to a maximum of 20mm. The actual reference to the engineering community, and should be
measured differential shortening between the core wall considered as part of the intelligent building
and the exterior columns have been found to be less system of important building in the world. Tower
than the predicted shortening. Palace III is a landmark tower for the city of Seoul.

CTBUH 2004 October 10~13, Seoul, Korea 661