Progressive Collapse Dynamic Response Analysis Of Steel Frame Structures

In recent year, with the rapid development of the civil engineering construction industry, steel structure has been more widely used. Currently, the design of the steel structural system in the normal loads has been quite perfect. However, progressive collapse behavior caused by accidental loads (fire, crash, explosion, etc.) still exist many detail worth explored. As we all know, the progressive collapse of the structure will usually cause more serious consequences, pose a threat to people’s lives and property safety. Therefore, the progressive collapse analysis and research of the steel structure have social significance.At present, alternate path method and accidental load method are widely used in progressive collapse dynamic response analysis of steel frame structures. In the first method, the specific reasons of destruction aren’t considered and the analysis process of structures is simplified. In the second method, different type accidental loads were involved. Based on these two methods, the finite element software ANSYS/LS-DYNA is used for nonlinear dynamic analysis of plane and space steel frame. This paper is mainly involved the following aspects:(1) Based on the alternate path method, the main analysis was involved:the influence of column’s failure time, failure position, strain rate effect on residual structure dynamic response. When the bottom side column failure, the structure of the redistribution of internal forces and the affected area of dynamic response were also analyzed. It has been revealed that the recommended failure time is no more than1/10of vertical vibration period of residual structure; bottom side column failure will cause the maximum structural dynamic response; the strain rate of the material should be considered. When the bottom side column failed, the change of internal force of columns that are close to the failure column were more significant.(2) The progressive collapse dynamic response of a space steel frame was studied via alternate path method. Dynamic response of structure that caused by failure of the underlying corner column and the short side column was comparatively large and were researched mainly. (3) Based on applied directly accidental load method and the introduction of failure criteria, bottom corner column of the space steel frame is eliminated to analyze the change of internal forces and the affected area of dynamic response.(4) Comparing these two methods and analysis results, the main conclusion is that the trends of internal forces is consistent basically, but the simulation results of the alternate path method is smaller. So it is suggested that directly accidental load method is applied instead of alternate path method.