Research On Seismic Behavior And Design Method Of Concrete-filled Square Steel Tubular Frame-Coupled Steel Plate Shear Walls With Cantilever Steel Coupling Beam

Coupled steel plate shear walls(CSPSW)employ steel coupling beam(CB)at each level to connect two SPSWs acting separately to form a whole structure.Under the horizontal seismic action,due to the link effect of the CB s,two adjacent SPSWs can work together to improve the structural resistance performance.This paper proposes a concretefilled square steel tubular frame-coupled steel plate shear walls with cantilever steel coupling beam(CFTF-CSPSW-CSCB),which can meet the needs of architecture,has a simple detail,and can be retrofitted quickly after the earthquake.The combination of experimental research,finite element numerical simulation and theoretical research were used to study the seismic performance and design method of CFTF-CSPSW-CSCB.The main contents are listed as follows:(1)A cyclic loading test was performed on a 3-layer,3-span CFTF-CSPSW-CSCB with scale of 1/3.The seismic performance of the CFTF-CSPSW-CSCB was studied.The results show that CFTF-CSPSW-CSCB has superior strength,ductility,energy dissipation and excellent structural performance.The replaceable section in the middle of the CB was yielded before other main parts of the structure.The cantilever on both ends of the CB remain elastic.The CBs can be easily replaced after the earthquake.(2)The finite element analysis software ABAQUS was used to perform nonlinear numerical simulation on the test specimen.The finite element analysis was compared with the test results.The results show that the finite element load-displacement hysteretic curve and skeleton curve were in good agreement with the test results,which verified the validity of the finite element modeling method.Combined with the test and finite element analysis results,the stress-strain development process of the specimen was analyzed,and the stress mechanism and failure mechanism of CFTF-CSPSW-CSCB were obtained.(3)Using the above-mentioned modeling method,full-scale finite element models were established.The impact of the degree of coupling(DC)and the length of the cantilever of the CB(L)on the hysteretic behavior of the CFTF-CSPSW-CSCB was investigate.The results show that CBs can reduce the stress on the inner columns in the frame,in structural design,the inner and outer columns of the frame can be designed as members with different cross-section.When DC is high,the section size of the CB is large and the bearing capacity of joints is required.When DC is low,the stiffness of CSPSW and two SPSWs acting separately is basically the same in the plastic stage.Therefore,DC should be within a reasonable range,the DC is recommended in the range of 0.3～0.5.The L is within 0.58 of the net span of the CB has little influence on the hysteretic performance of the CFTF-CSPSW-CSCB.When the L is excessive,the replaceable section in the middle of the CB presents a shear failure,and the internal force of the cantilever is huge.Then the CB is inconsistent with the design goal of the cantilever.The L is recommended to be small 50%of the net span of the CB.(4)Based on the results of the experimental and finite element analysis,combined with the analysis of the mechanical performance of CSPSW,the design method of CFTFCSPSW-CSCB with shear failure of CBs was proposed.The numerical example shows that CFTF-CSPSW-CSCB designed according to the design method proposed in this paper can achieve the ideal failure mechanism of CSPSW.