Study On Mechanical Property And Design Method Of Self-centering Concrete-filled Square Steel Tubular Frame With Thin Steel Plate Shear Walls

Self-centering structure is a new kind of structure form with the target to reduce the seismic residual deformation.Its core technology is the use of post tensioning pre-stress to make the structure has self-centering ability and solve the problem of residual deformation of structures.This dissertation presents a new type of self-centering concrete-filled square steel tubular frame(SC-CFSTF),combined with thin steel plate shear wall(SPSW)as a component to resist lateral force and energy dissipation,which form a new lateral structure system.Analysis method of combining theory and finite element in this dissertation,analyzing the mechanical property of SC-CFSTF with thin SPSW,and putting forward the design method.The main contents are as follows:(1)According to the traditional seismic joint and self-centering joint,a new self-centering center-line rocking joint was proposed.New self-centering joint has the advantages of simple structure,and no need to set the energy dissipation element on the joint.The joint was in elastic during the earthquake process.(2)Force analysis has been conducted to the edge elements of SC-CFSTF,calculating the internal force under the strand tensile stress and tension filed of thin SPSW,respectively.The edge component is defined and it can concluded that the maximum moment is at the location of beam anchor the steel strand;the part of beam between the anchor point and rotation point has the maximum axial force;the maximum moment and shear force on column are at the same position,which correspond to the midline of beam on vertical direction,and the node position of the column is endured the local concentrated stress.This paper analysis frame columns under compression,bending,shear interaction.(3)Formula of lateral stiffness of SC-CFSTF has been derived and verified by the finite element analysis.Considering the effect of pre-stress and section area of strand on the lateral performance and self-centering ability.The results show that the new self-centering frame has good self restoring ability;with the cross-sectional area increases of strands,the frame lateral stiffness and bearing capacity increases;when the steel strand is elastic,the initial pre-stress has small effect on lateral stiffness of SC-CFSTF.(4)The stiffness relation between SC-CFSTF and SPSW has been analyzed,and gave the proposed initial stiffness value of SC-CFSTF.Put forward the range of pre-stressed strand initial value,and the calculation formula of section area of strand,finally proposed the design method of SC-CFSTF with thin SPSW.A full size specimens has been designed by the method and analyzed through the finite element software-ABAQUS 6.12.The analysis results show that the designed self-centering structure has the better restoration ability and energy dissipation.Hysteretic curve is double flag shape which corresponded to the ideal self-centering performance.At the end of loading,SPSW has been fully yield and form tension field,while the SC-CFSTF keeps elastic state,which means the realized of the ideal self-centering target.