Analysis Of Collapse Margin Of Multi-Story Steel Frame

Recent years, collapse margin of building structure attracts more and more engineering researchers'attention. What has become a research hotspot and the priority of seismic field is how to reasonably evaluate and quantify the collapse margin of steel structure.This paper summarizes the detailed steps of incremental dynamic analysis method and the selections on key factors relate to the method. This paper also makes conclusions on the indicators of five performance levels including slight damage, moderate damage, serious damage and collapse of multi-layer steel framework structure.In this paper, the collapse reserve coefficient and seismic vulnerability are used to evaluate the collapse margin of the four story steel frame structure designed in the present code. This paper sets up three analysis models for the study of influence of square steel tube column width to thickness ratio on the multi-layer steel framework structure collapse resistant capacity. The research results show that the larger the width thickness ratio of the steel column is, the greater the probability of the multi-layer steel frame structure reaches the corresponding limit state, the stronger the collapse margin is. In the elastic-plastic stage of the steel frame structure, the width thickness ratio of the bottom steel column has a significant influence on the lateral capacity of the steel frame, and the increase of the width to thickness ratio of the bottom column can effectively reduce the failure probability of the steel frame structure.