Research On Damping Performance Of The Steel Frame With Bending-shear Combined Mild Steel Energy Dissipator

Steel frame structures exhibit excellent mechanical properties and are widely used.It is very important to ensure the safety and stability of steel frame structures under earthquake.In this paper,the bending-shear combined mild steel energy dissipator is presented.The bending plate is arranged on both sides of the shear plate,and the bending plate and the shear plate contact closely.The bending plate can not only work independently with the shear plate,but also provide lateral restraint for the shear plate.Thus,the mechanical properties of the bendingshear combined mild steel energy dissipator are improved.The bending-shear combined mild steel energy dissipator is installed in the steel frame structure,which can improve the seismic performance of the structure by yielding energy dissipation and increasing structural stiffness.Through the theoretical analysis of the force and deformation,the calculation formula of yield displacement and yield force of the bending plate and the shear plate is deduced,and the section design method is obtained.Three bending-shear energy dissipators are designed,and the effects of the number and thickness of bending plates on the dissipators are studied.At the same time,a shearing plate energy dissipator and a bending plate energy dissipator are designed as contrast specimens.Five energy dissipators are designed,including three bending-shear combined mild steel energy dissipators,one bending-plate energy dissipator and one shearingplate energy dissipator.The mechanical properties of the specimens were studied by using the ABAQUS software.The results indicate that the bending-shear combined energy dissipator shows excellent mechanical properties,can yield under small displacement,and has stable hysteretic performance and good energy dissipation capacity through the reasonable combination design of the bending plate and the shear plate.The reduction of the number of bending plates will weaken the constraint effect on the shear plate.With the decrease of the thickness of the bending plate,the stiffness of the bending plate itself becomes weak,which is not conducive to the effective restraint of the shear plate.The elastoplastic time-history analysis of steel frame without energy dissipator(FM-1),steel frame with shear-plate energy dissipator(FDM-1)and steel frame with bending-shear combined type energy dissipator(FDM-2)was carried out by Perform-3D analysis software.The natural vibration period and the whole dynamic response of the structure are studied.The analysis results show that the installation of the bending-shear combined energy dissipator can effectively increase the lateral stiffness of the structure,and significantly reduce the inter-storey displacement Angle and inter-storey shear force of the structure.The bending-shear combined mild steel energy dissipator can effectively derease the hysteretic energy dissipation of the structure,which can mitigate earthquake damage to components.Based on IDA analysis method,the collapse resistance of steel frame without energy damper(FM-1),steel frame with shear-plate energy damper(FDM-1)and steel frame with bending-shear combined mild steel energy damper(FDM-2)was evaluated.The vulnerability curves of the three models under different performance level states were analyzed.The results show that the collapse overpass probability of FM-1,FDM-1 and FDM-2 are 58.2%,31.6% and25.3%,respectively,under 8 degree rare earthquake.Therefore,the collapse-resisting ability of steel frame structure can be improved by setting the combined bending-shear type mild steel energy damper.