Study On Seismic Collapse Criterion For Steel Frame Structures Based On Pushover Analysis

Steel structure has been very widely used in building structure,and its seismic performance is generally thought excellent.But large number of disaster investigations show that steel frame under strong earthquake still has local damage,even the event of overall collapse,in addition,most of the casualties and property losses in the earthquake were caused by the collapse of buildings leaded to by post-earthquake.At present,the structural seismic research at home and abroad considers the effect of preceding-earthquake and post-earthquake less,that is considering the effect of loading paths on the structural earthquake collapse performance very few.Therefore,it has great practical significance to study the anti-collapse performance of the steel frame structure under strong earthquake,and to focus on analyzing the effect of loading paths on the anti-collapse performance of the structure.In this paper,on the basis of reviewing damage models at home and abroad,the damage model based on structure layer is improved,and then a structural damage model based on pushover analysis is established.Furthermore,finite element program ABAQUS is used to analyze the anti-collapse performance,damage evolution law of steel frame under strong earthquake and the effect of loading paths on the anti-collapse performance and damage evolution of steel frame.The results show that:1.Based on finite element program ABAQUS,the collapse numerical simulation results of two-layer and two-span plane steel frame can reflect the collapse failure characteristics and performance degradation of steel frame under strong earthquake truly.The energy dissipation of the plane steel frame structure collapse is mainly from the consumption of the underlying structure.the overall collapse is caused by the damage of the underlying structure.2.In this paper,the proposed overall structure damage model can reflect the damage evolution law of steel frame structure under strong earthquake better.The maximum interlayer displacement angle is 1/23(about two times the interlayer displacement angle limit of 1/50 given by specification),and it is not the same in different floors.3.The analysis of anti-collapse performance and damage evolution of steel frames under three seismic sequences shows that the lateral bearing capacity and cumulative hysteretic energy dissipation of steel frame structure are the highest under loading paths ?(main-earthquake and post-earthquake),are the second under loading paths ?(preceding-earthquake,main-earthquake and post-earthquake),and are the lowest under loading paths I(preceding-earthquake and main-earthquake).And at the end of the loading,the overall damage index of steel frame structure is opposite to the above rule.4.The energy consumption and overall damage of the steel frame structure under loading paths I occur at the final stage of loading,mainly occur in the initial stage of loading under loading paths ?,and mainly occur in the middle stage of loading under loading paths ?.