Complex building in Wuhan

Building use

Complex building

Country/Region

China

Overview

The structure is a frame-core tube-outrigger truss hybrid system. The lateral force resistance system consists of three parts : the reinforced concrete core tube with built-in steel plate or steel in some floors, the frame formed by CFT column and steel beam with six ring truss reinforcement, and the three outrigger truss connecting the core tube and the frame.

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

Construction date: 2015
Number of stories: 88
Gross floor area: 267,000m2 Adopted design code: GB 50068-2001; GB 50153-2008; GB 50223-2008; GB 50045-95 (2005 Edition); GB 50009-2001 (2006 Edition); GB 50011-2001 (2008 Edition); GB 50010-2002; GB 50017-2003; JGJ 3-2002; JGJ 138-2001; CECS 28: 90; CECS 230: 2008)
Engineer(s): East China Architectural Design and Research Institute Co., Ltd.
Contractor(s): China Construction Third Engineering Bureau Co., Ltd

Issue and/or innovation

1. In this project, a floor system combining steel beams and composite slabs with lighter weight than reinforced concrete floors is adopted. The frame columns use CFT columns that can provide sufficient stiffness and facilitate connection with steel beams. The shear walls in the reinforced concrete core tube adopt concrete shear walls with built-in steel plates or steel steels to control wall thickness.
2. The maximum diameter of the bottom layer of the CFT column directly connected with the outrigger truss is 3.0m. In order to strengthen the interaction between steel tube and concrete, measures such as built-in structural steel cage, longitudinal stiffeners and studs are arranged on the inner wall.
3. The bottom area of this project adopts the steel plate concrete shear wall with built-in steel plate or section steel, and the maximum thickness of the bottom layer is 1.2m. Under the premise of meeting the requirements of structural bearing capacity, it also meets the requirements of wall thickness and effectively improves the use efficiency of the building.
4. The steel plate or steel oblique bracing shear wall used in the outrigger truss floor of this project meets the force demand of the outrigger truss to the shear wall of less thickness.

Reason for composite solution

The purpose of using CFT column is as follows:
1. In the lateral force resistence system of this project, there are 8 outer frame steel tube columns connected to each other through the outrigger truss and the core tube, which requires the frame column to have sufficient stiffness to participate in the work of the anti-lateral system.
2. Under the same size conditions, the bearing capacity of CFT column is higher. The use of CFT column can reduce the size of the frame column, and the reduction of the size of the frame column can improve the utilization rate of the building plane.
3. Better seismic performance : CFT columns have ductile failure characteristics, stronger plastic deformation capacity and energy dissipation capacity.
4. The construction of CFT column is simple, and there is no need for formwork when pouring concrete. Also, the connection with the steel structure floor beam is direct and simple.
The purpose of using steel plate or SRC shear wall is as follows:
1. Control the thickness of shear wall and improve the utilization rate of building plane.
2. The shear wall of outrigger truss floor requires built-in steel or steel plate to meet the large force demand of outrigger truss to shear wall.
3. Compared with the reinforced concrete shear wall, the steel plate concrete shear wall reduces the thickness of the shear wall and the weight of the structure, thus reducing the adverse effects of the earthquake.
4. Good seismic performance: Steel plate or steel reinforced concrete shear wall has ductile failure characteristics, its hysteresis curve is fuller than ordinary reinforced concrete shear wall, and has strong plastic deformation capacity and energy dissipation capacity.

Specific solution/technical details

1. The diameter of the CFT column at bottom of the structure is 3.0m, which is larger than the size of the commonly used CFT column. In this project, through finite element numerical analysis and experimental study of CFT columns with multi-layer frame beams, the basic law that the large-diameter CFT columns are effectively transferred from the steel beams and trusses connected to the outer steel tubes to the concrete inside the steel tubes and the effective diffusion in the concrete along the column height is understood. The steel plate, studs and steel cages are arranged on the inner wall of the steel tube to ensure that the outer steel tube and the internal concrete can work together under axial compression.
2. The focus of the bottom shear wall of this project is to control the wall pressure ratio under the representative value of gravity load is not greater than 0.5. Under this condition, the built-in steel plate concrete shear wall is used to reduce the thickness of the shear wall, and according to the force of the wall limb, the joints between the adjacent steel plates in most of the wall limbs are connected by high-strength bolts, which further improves the construction speed.
3. Through the analysis of modelling, finite element numerical analysis of the critical members and the component test, the connection joints between the outrigger truss and the core tube are studied. The verification and improvement of the embedded and wrapped outside joints at the intersection point of the cross-shaped outrigger truss are carried out, which ensures the bearing capacity of the steel-concrete composite member at the critical locations.

Impact or effectiveness

1. In this project, CFT column composite components are used to make full use of the advantages of the two materials. Compared with reinforced concrete columns, it can effectively reduce the section size of columns and improve the utilization efficiency of building plan. During the construction, the steel tube and steel beam of the CFT columns form a relatively stable temporary structure. As a support skeleton, it is combined with the use of profiled steel plate or steel bar truss floor plate, which removes the on-site formwork process. The steel tube itself also acts as the external mold during the pouring of the concrete, which greatly speeds up the on-site construction.
2. Compared with the concrete shear wall, the steel plate or steel reinforced concrete shear wall used in this project significantly reduces the thickness of the shear wall and has better seismic ductility performance. The steel plate and steel reinforced concrete shear wall used in the strengthening floors such as the outrigger truss can meet the demand of high bearing capacity. The steel and concrete composite members used in the corner of the core tube not only ensure the connection with the steel components of the outer outrigger truss, but also fully guarantee the interaction between the core tube reinforced concrete shear wall and the outrigger truss through the connection interface between the steel components and the concrete.

References / Technical Papers Content

Zhou, J., Chen, K., and Zhang Y. 2012. “Structural design on Wuhan Center Tower”. Building Structure. 42(5): 8-12. https://doi.org/10.19701/j.jzjg.2012.05.002
Chen, K., and Zhou, J. 2017 “Design and Research on Outrigger of Wuhan Center Tower”. Progress in Steel Building Structures. 19(5): 9-14. https://doi.org/10.13969/j.cnki.cn31-1893.2017.05.002