Experimental And Numerical Research Of Buckling Process On Fire Of Elastic Restrained Circular Steel Tube

Space frame structures are widely used in all kinds of buildings.The research on the residual bearing capacity of space frame structures after fire is of great significance for post-fire safety assessment and structural restoration.Buckling failure is a complex process.At present,numerical simulation of buckling process on fire of elastic restrained circular steel tube in space frame structures has been carried out.On this basis,the numerical simulation method is tested in this paper to verify the accuracy of the finite element analysis method.In order to investigate the effects of slenderness ratio and axial restraint stiffness ratio of resistance performance on fire and residual performance after fire,buckling process on fire of five axially loaded circular steel tubes with restraints were carried out.The experimental data such as furnace temperature-time curve,specimen temperature-time curve,axial displacement-temperature curve,mid-span lateral displacement-temperature curve and failure state of specimens were obtained.Through the analysis of the above curves,the buckling temperature,the axial displacement,the maximum mid-span lateral displacement and residual mid-span lateral displacement of the specimens are obtained.Through finite element analysis software ABAQUS,the integral model of solid element and the model of shell element were compared and analyzed and a test sample was analyzed by sequential coupled thermo-mechanical coupling analysis method.The finite element numerical simulation of all test specimens was carried out by using shell element direct coupled analysis.The results of finite element analysis and test,such as axial displacement-temperature curve,mid-span lateral displacement-temperature curve and failure mode,were compared.The correctness of finite element analysis was proved.The difference of finite element analysis between test and ideal conditions is the existence of initial stress and bottom tension bearing.The comparison of the force effect and temperature effect on the stability of compression bar was carried out.The research content of this paper can be used as a reference for the identification and renovation of space frame structures after fire,and provide areference for the study of residual bearing capacity of space frame structures after fire.