Complex building in Shanghai (Shanghai Tower)

Complex building in Shanghai (Shanghai Tower)

Building use

Complex building

Country/Region

China

Overview

Mega columns with wang-shaped steel and shear walls embedded with steel plates were adopted. The purpose of using steel-concrete composite columns and shear walls is to leverage the mechanical properties of different materials, increase the section bearing capacity, enhance the anti-seismic performance of the building, and reduce component size for more usable space.

Basic information (construction date, number of stories, gross floor area, adopted design code, engineer(s), Contractor(s), etc.)

Construction date: 2016
Number of stories: 127
Gross floor area: 520,000m2
Adopted design code: GB50068-2001; GB50009-2001; GB 50010-2002; GB 50011-2001(2008); JGJ 3-2002; GB50017-2003; JGJ 99-98; JGJ 138-2001; GB50007-2002; JGJ6-99; JGJ 102-2003; GB50223-2008; JGJ94-2008
Engineer(s): Architectural Design & Research Institute of Tongji University(Group)Co., Ltd
Contractor(s): Shanghai Construction Group

Issue and/or innovation

The structural design of the Shanghai Tower was systematically and thoroughly studied from three aspects: foundation and excavation engineering, main structure design, and flexible suspended curtain wall support structure design. The key technological innovations include: 1. Selection, design, and analysis of pile foundation for super tall buildings on deep soft soil foundations. The construction of ultra-long bored piles in Shanghai’s soft soil foundation requires crossing a thick sand layer, and post-grouting can effectively compensate for the reduction of lateral frictional resistance. Variable-stiffness leveling design is based on settlement control, which has a significant effect on controlling the differential settlement of high-rise buildings on group pile foundations and soft soil foundations.
2. Design of giant frame structures for super tall buildings. The “mega frame-core tube-outrigger truss” system provides considerable redundancy for the structure. Compared with the conventional frame-core tube system, it has six outer cantilever trusses that can provide an additional seismic bearing capacity. By performing performance-based design, finite element analysis, and seismic tests on various components and joints of the mega structure system, the safety and reliability of the structure are ensured.
3. Design of a suspended curtain wall support structure system.
A suspended curtain wall support structure system was proposed, which allows vertical free deformation relative to the main structure and reduces the level of stress on the curtain wall support structure. As a result, the component section is smaller, the structure is lightweight and transparent, and there is minimal visual obstruction. Meanwhile, the structure uses less steel and is highly constructible.

Reason for composite solution

The Shanghai Tower adopted mega columns with Wang-shaped steel and shear walls embedded with steel plates. The purpose of using steel-concrete composite columns and shear walls is to leverage the mechanical properties of different materials, increase the section bearing capacity, enhance the anti-seismic performance of the building, and reduce component size for more usable space.
The SRC frame column employs Wang-shaped solid web steel arrangement, forming multiple enclosed areas that effectively constrain concrete and improve the column’s compressive load-carrying capacity. The joint core of the strengthened storeys directly connect the outrigger truss and belt truss to the “王”-shape steel, enabling the entire column section to participate in resistance. The assembled “王” shaped steel skeleton can be directly welded at the factory, reducing welding workload and ensuring high construction quality. The steel plate shear wall can reduce the tensile stress generated by the piers under horizontal loads, prevent cracking caused by eccentric tensile stress, and improve the ductility of the piers. The use of steel can effectively reduce the thickness of the piers, optimize the core tube dimensions, reduce the amount of steel reinforcement, and decrease on-site steel tying work while ensuring the piers’ bearing capacity and stiffness.

Specific solution/technical details

The Shanghai Tower’s “mega frame-core tube-outrigger” structural system uses a combination of components for both the mega frame and core tube, which serve as the main lateral force resisting members. The core tube is a reinforced concrete square tube with a side length of about 30 meters, featuring steel plates embedded in the base reinforcement area and steel bones arranged in the edge components of the upper region. The thickness of the wing wall at the bottom of the core tube is 1.2 meters, gradually decreasing with height until it reaches 0.5 meters at the top. The steel structural components of the outrigger will penetrate the abdominal wall of the core tube, with the thickness of the abdominal wall decreasing from 0.9 meters at the bottom to 0.5 meters at the top to ensure continuous and uniform stiffness changes and an appropriate wall pressure ratio.
The mega frame consists of eight mega columns connected by two layers of high box-type space trusses on each reinforced layer. The eight mega columns terminate at the eighth partition, while the four corner columns end at the fifth partition. Four corner columns arranged diagonally below the sixth partition are mainly used to reduce the span of the box-type space truss. The mega column in the mega frame adopts a steel-concrete composite column, with a single-branch mega composite steel column spliced together by steel plates inside. The steel content of the mega column is controlled at around 4% to 5% (greater than 4% in the bottom 2-7 partitions, greater than 5% in the first and eighth partitions). High-strength concrete (C70) is used at the bottom of the mega column to reduce its cross-sectional size. The size of the mega column gradually decreases with height. The axial compression ratio of the mega column is controlled within the specification limit of 0.65.

Impact or effectiveness

Through the use of steel ribs in the giant columns and core tubes of Shanghai center Building, the giant columns and shear walls can better meet the seismic performance target requirements. The downforce stress of the shear wall under the seismic action is controlled within 2 times ftk, and the concrete does not collapse under the action of rare earthquakes. The internal steel stress does not exceed the steel yield stress.
Both the shear wall and the giant column show good ductility. At the same time, through vertical load optimization technology, the size of giant columns and the thickness of shear walls are further reduced, increasing the usable area of the building. The reduction in the dead weight of the structure also reduces the seismic action on the structure, ensuring that the overall stiffness to weight ratio and shear weight ratio of the structure meet the requirements of the code, and achieving better seismic performance of the structure.

References / Technical Papers Content

Ding Jiemin, Chao Si, Zhao Xin. Critical issues of structural analysis for the Shanghai Center project[J]. Journal of Building Structures, 2010,31(6):122-131.
Ding Jiemin, Li Jiupeng, He Zhijun. Research on key joints design of mega frame of[J]. Journal of Building Structures, 2011,32(7):31-39.
Lu Tiantian, ZHao Xin, Ding Jiemin, CHao Si. Stability analysis of the Shanghai Tower and research on effective length of super column[J]. Journal of Building Structures, 2011,32(7):8-14. Chen Yiyi, Wang Bin, Zhao XIanzhong. Hysteretic tests on outrigger truss and its connection with mega column and core tube of the Shanghai Tower[J]. Journal of Building Structures, 2013,34(2):29-36.
He Zhijun, Ding Jiemin, Lu Tiantian. Vertical earthquake action analysis for mega frame-core tube structure of the Shanghai Tower[J]. Journal of Building Structures, 2014,35(1):27-33.