Research On Evaluation Method Of The Resisting Progressive Collapse Of Large-span Spatial Structure Under Fire

The problem of progressive collapse of the structure caused by local failure has attracted extensive attention from scholars at home and abroad.The research mainly focuses on the resisting progressive collapse performance of the structure under normal temperature conditions.The research on the resisting progressive collapse performance of the structure under high temperature has not been fully developed.With the wide application of spatial structure,the cases of progressive collapse of the spatial structure under fire are common.Therefore,it is necessary to study the resisting progressive collapse performance of the spatial structure under fire.In this paper,the structural robustness is used to study the resisting progressive collapse performance of large-span spatial structures under fire.The research work is mainly carried out from the following aspects.(1)In order to to study the effect of a single structural member on the fire to other structural members,taking the stress variation of the structural member as the analysis parameter,the formula for calculating the sensitivity coefficient of structural member at high temperature is proposed.And based on the statistical fitting of the structural sensitivity coefficient,the formula for calculating the importance coefficient of the structural component is proposed.Combined with the maximum displacement of the structure under high temperature,the formula for calculating the structural robustness index at high temperature is proposed.(2)Taking the plane rigid frame structure and space steel frame structure as the research object,analyzing the influence of structural components on the fire to adjacent components,the sensitivity coefficient of structural member and importance coefficient of the structural component of the two structures are calculated.And the variation of the sensitivity coefficient of structural member and the importance coefficient of the structural component with the temperature and geometric distribution position of the plane rigid frame structure and the space steel frame structure are discussed respectively.(3)A method based on structural robustness for evaluating the resisting progressive collapse performance of large-span spatial structures under fire is proposed.Designing a quadrangular cone grid structure,and using ANSYS software builds a finite element model and performs numerical simulation.The the sensitivity coefficient of structural member,the importance coefficient of the structural component and structural robustness index of the structure under different temperatures are calculated.Using the evaluation method presented in this paper evaluates the resisting progressive collapse performance of the quadrangular cone grid structure.And the law of structural robustness index changing with temperature and geometrical position of fired area is analyzed.(4)Using the evaluation method presented in this paper evaluates the resisting progressive collapse performance of TVCC building's F area grid structure under fire.According to the evaluation results,the weakest area in the grid structure is obtained.Comparing the evaluation results with the research results of the research team on the evaluation and disassembly of the F-frame structure after the TVCC structure fire,it is found that the weakest area of the structure obtained by this evaluation method is the same as the area where the structure is first removed.The rationality of this evaluation method has been verified.