Study On Mechanical Performance Of Steel Plate Shear Wall Buckling-restrained By Cold-formed Steel Members

Steel plate shear wall(SPSW)is a new type of highly efficient lateral force resisting system developed in the 1970 s.Compared with the traditional reinforced concrete shear wall,the SPSW enjoys the advantages of good ductility,superior seismic performance,light weight,high construction efficiency,easy repairing,easy dismantling and recyclability and so on.Subjected to horizontal load,the thin SPSW(height-to-thickness ratio of steel plate is greater than 150)still has considerable post-buckling strength and ductility.This post-buckling strength is derived from the mechanism of tension field,which can provide stable bearing capacity and lateral stiffness for SPSW.Due to the out-of-plane buckling deformation,there are some defects in mechanical properties of the SPSW,such as: the "pinching" of steel plate under horizontal cyclic loading,the noise and vibration produced during the loading process;the tension field effect causing additional bending moments to the vertical edge members.Therefore,in order to improve the deficiency of the SPSW,reduce the out-of-plane deformation of the steel plate,the corresponding structural measures should be adopted to restrain the out-of-plane buckling deformation of the SPSW,such as using steel plate welding stiffener and adding concrete cover plate on both sides of the steel plate.The buckling restrained SPSW has advantages of high ductility,strong hysteretic energy dissipation capacity,large elastic lateral stiffness and bearing capacity.Therefore,it is of great significance to study the buckling restrained SPSW.The main works reported inthis thesis are as follows:(1)Based on the SPSW structure,which is mainly composed of embedded steel plate,cold-formed steel,thermal insulation and sound insulation materials and oriented strand board(OSB)plate,the quasi-static tests of hinged frame-SPSW buckling-restrained by cold-formed steel members were carried out.The energy dissipation capacity,stiffness degradation,ductility and bearing capacity of SPSWs with different buckling constraints were analysed.(2)A finite element(FE)model of hinged frame-SPSW buckling-restrained by cold-formed steel members was developed and validated against experimental results in terms of the failure modes,skeleton curves and bearing capacity of the specimens.Upon validation,the buckling performance of SPSW buckling-restrained by cold-formed steel members was analysed.The minimum stiffness ratio of cold-formed steel to SPSW was proposed.In addition,the design method of shear elastic buckling coefficient and elastic shear bearing capacity of SPSW buckling-restrained by cold-formed steel members were proposed.(3)The quasi-static tests of four composite frame-SPSW buckling-restrained by cold-formed steel members structures were carried out.The hysteretic performance,failure mode,energy dissipation capacity,stiffness degradation and column lateral deformation of the specimens were analysed.Meanwhile,the different failure modes of the hinged frame and composite frame shear wall structure were analysed,and it was concluded that the stiffness of the edge frame has a significant influence on the embedded steel plate.(4)The FE model of SPSW buckling-restrained by cold-formed steel members was established.Upon validation,a parametric study was carried out to analyse the axial compression ratio,steel plate strength,concrete strength,column flexibility,strength of square concrete-filled steel tube column and width to thickness ratio,width to height ratio of embedded steel plate.Additionally,the interaction mechanism between composite frame and embedded steel plate and the stress uniformity of embedded steel plate was analysed.The minimum stiffness requirement of square concrete-filled steel tube column which can make the strength of SPSW buckling-restrained by cold-formed steel members be fully used was proposed.(5)Regarding to the steel bar buckling theory,combined with the form of cold-formed steel buckling restrained and the buckling restraint mechanism of SPSW buckling-restrained by cold-formed steel members,an equivalent oblique cross brace simplified analysis model was proposed,which was suitable for SPSW buckling-restrained by cold-formed steel members.The results show that the proposed simplified analysis model is accurate and consistent.