Study On The Influence Of Large-span Hollow Slabs On Structural Continuous Collapse Capacity In High-rise Frame Structures

In recent years,frequent accidents of progressive collapse caused by disasters including earthquakes,fires,tsunamis and explosions have led to continuous research of scholars in the field of it.Researches on progressive collapse abroad have been quite systematic,while it still remains to be explored in China.On the other hand,with the development of China's economy,the large-span hollow floor structure has been widely used in high-rise buildings,which has profound research significance.In this study,the influence of the large-span hollow floor on high-rise frame structure's resistance to progressive collapse is analyzed through structural analysis software SAP2000.The research object selects an actual engineering project designed according to the current domestic codes,a 27 m high-rise frame structure with 20m×24m large-span hollow floor.The specific content of this paper is as follows:1.Establish two structural models:(1)pure beam-column frame structure and(2)frame structure with plates.Then carry out static nonlinear analysis(pushdown analysis)based on alternative path method,analyze the influence of large-span hollow floor on the resistance to progressive collapse from the aspects of structural bearing capacity,deformation capacity,failure degree and mechanical behaviors of key components.2.By comparing the progressive collapse mechanism of two structural models,the rule of progressive collapse of the high-rise frame structure under initial failure is summarized.Then determine whether the studied structure designed conventionally satisfies the requirements for resistance to progressive collapse,and put forward relevant design suggestions.3.Analyze the influence of large-span hollow floor parameters(such as reinforcement ratio,concrete intensity,thickness and hollow rate)on resistance to progressive collapse,and propose relevant design suggestions of large-span hollow floor.It is found that large-span hollow floor can effectively improve a structure's resistance to progressive collapse and mitigate the collapse failure.Therefore the effect of slab should be considered during the design of resistance to progressive collapse.With the effect of floor,the high-rise structure with large-span hollow floor under 6-degree seismic design in this study meets the requirements for resistance to progressive collapse.,indicating the applicability and high economic efficiency of the hollow slab in the large-span frame structure.However,the failure mechanism of the structure presents “strong beam weak column”,it has a low bearing capacity after the removal of the bottom columns,and it gets the lowest after the removal of the corner columns.It is recommended to further strengthen the design of the “strong column weak beam” and strengthen the bottom columns,especially the corner columns during the practical design of resistance to progressive collapse.And the reinforcement ratio,thickness and hollow rate of large-span hollow floor have great influence on the structure's resistance to progressive collapse,therefore it could be improved by appropriately increasing the reinforcement ratio or reducing the hollow rate of the floor.