Studies On Seismic Behaviours Of Double Skin Composite Shear Walls And Mega-sub Structure

In a super high-rise building,the shear walls is the main lateral force member of the structure,and their seismic performance is very important to the safety of the structure.With the increase of building height,how to reduce structural gravity and improve the seismic performance of shear walls is the key to the seismic design of super high-rise buildings.This paper takes the Mega-sub structure as the research object and introduces a double skin composite shear walls as the main lateral force member of the structure.The seismic performance of the Mega-sub structure is studied by the nonlinear analysis method.Through the damage state and key damage position of the structure under seismic action,the primary research contents of this paper are put forward,and a series of systematic and in-depth studies were carried out.The conclusions are stated as follows:1.Taking the Mega-sub structure as the research object,the double skin composite shear walls are adopted as the main lateral force members of the structure,and the optimization design method of the Mega-sub structure is based on the design idea of "mega-sub separation" is proposed.The nonlinear analysis of the Mega-sub structure is carried out,and the dynamic response,performance level,and critical damage location of the structure under different seismic levels are obtained.A simplified multi-degree-of-freedom analysis model of the Mega-sub structure was established.Considering the weight coefficient of the displacement drift between floors and the floor acceleration,an optimization design method of the Mega-sub structure based on a genetic algorithm was proposed to select the damping and isolation devices and optimize the layout scheme.The results show that the designed Mega-sub structure satisfied the seismic design requirements,and the proposed optimization algorithm has a good effect on improving the seismic response of the Mega-sub isolation structure system.2.The quasi-static loading tests were carried out on 5 double skin composite shear walls-coupling beam connections.The specimens included two connections with different embedded bar arrangement schemes and three connections with different embedded lengths of the steel beam.Mechanical properties such as failure mode,bearing capacity,and energy consumption of double skin composite shear wallscoupling beam connections are analyzed.The results show that the key factors affecting the connection strength are seam tearing and concrete crushing.The failure mode and mechanical properties of two connections with different embedded bar arrangement schemes are close.The connection of the steel beam has high initial stiffness and the deformation ability of the connection can be improved by increasing the length of the embedded beam.On the basis of the experiment,the improvement measures and design suggestions are given to guide the practical engineering application.3.The finite element software was used to model and calculate 5 double skin composite shear walls-coupling beam connections.Taking into account the nonlinearity of the material,the non-linearity of the contact and the tearing of the steel,the stress characteristics and failure mechanism of the double skin composite shear wallscoupling beam connections are analyzed by combining the experimental results with the finite element method,further,a simplified mechanical model and calculation formula for different connections are proposed.4.The in-plane pseudo-static loading test was carried out on 8 internal steel trussdouble skin composite shear walls specimens.The influence of axial compression ratio,steel truss strength,and bolts on the mechanical properties of composite walls is studied.Through the in-depth analysis of the experimental results,the variation of mechanical properties,such as failure mode,bearing capacity,and energy consumption,are obtained.The results show that the internal steel truss-double skin composite shear walls exhibits the characteristics of bending failure,including the local buckling of the steel plate,the tearing of the vertical seam of the steel plate,the crushing of concrete at the bottom of the wall,and the tensile and compressive buckling of the chord member of the internal steel truss.The ductility of the shear wall decreases with the increase of axial pressure ratio,the bearing capacity and the initial stiffness are increasing with the increase of the strength of the steel truss,and the mechanical properties of the internal steel truss-double skin composite shear walls specimens are less affected by the presence of bolts on the steel truss.5.Six experimental models and 12 supplementary models of internal steel trussdouble skin composite shear walls were calculated by the finite element modeling method.The stress pattern and failure mechanism of the composite shear walls are studied in detail.The results show that the size of the truss chord has a great influence on the bearing capacity of the composite wall.Based on the test data,a simplified calculation model and calculation assumptions of the composite shear walls are proposed,and the calculation formula of the bearing capacity of the composite shear walls are given.