Study on key issues of progressive collapse resistance capacity analysis for complex high-rise steel structure

Based on the alternate path method and explicit dynamic finite element method,the key issues as the selection method of removal component, the failure simulation method of components and the setting of damage evaluation criteria of progressive collapse resistance capacity analysis for complex high-rise steel structure were studied in this research. The analysis results show that the importance of removal components can be evaluated by the sensitivity index of vertical components of the high-rise steel structure, and the progressive collapse resistance capacity of remained structure can be evaluated by the sensitivity index of horizontal components. In addition, a new simulating method of component failure using fiber model was proposed based on the generalized force-deformation relation for steel components of FEMA 356. This method can not only match the component deformation limit of FEMA 356 but also meet the maximum strain limit of material; damage of the remaining components can also be evaluated by the relation between the FEMA 356 performance level and microscopic material strain according to this method. Using this method, the progressive collapse resistance capacity of the steel structure of the case project was analyzed, and the results show that: progressive collapse does not appear after the key component is removed, and the remaining structure can form an effective alternative path; plastic hinge of most components do not reach the immediate occupancy performance level, and the components with large plastic deformation are mainly concentrated on the components in alternative paths. © 2019, Editorial Office of Journal of Building Structures. All right reserved.