ctbuh.org/papers Title: Integration of Design and Construction of the Tallest Building in Korea Authors: Ahmad Abdelrazaq, Executive Director, Samsung E&C William Baker, Partner, Skidmore, Owings & Merrill Kwang Ryang Chung, Principal, Dong Yang Structural Engineers J Pawlikowski, Vice President, Samsung E&C Insoo Wang, Manager, Samsung E&C Subjects: Building Case Study Structural Engineering Keywords: Concrete Foundation Outriggers Publication Date: 2004 Original Publication: CTBUH 2004 Seoul Conference Paper Type: 1. Book chapter/Part chapter 2. Journal paper 3. Conference proceeding 4. Unpublished conference paper 5. Magazine article 6. Unpublished © Council on Tall Buildings and Urban Habitat / Ahmad Abdelrazaq; William Baker; Kwang Ryang Chung; J Pawlikowski; Insoo Wang Integration of Design and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 2Partner, 4Associate, Skidmore, Owings & Merrill LLP, Chicago, USA 3Principal, Dong Yang Structural Engineering Co., Ltd, Seoul, Korea 4Vice President, 5Manager, Samsung Corporation, Construction & Engineering Group Abstract Tower Palace III was conceived as a 93-story residential tower soaring 320 meters into Seoul’s 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 Contractor’s 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, [email protected] 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 tower’s 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 building’s briefly discusses the instrumentation of the tower to upper zone; and evaluate the long term behavior of the composite c) creating irregularities along the building’s 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