Study On Axial Bearing Capacity Of Concrete Filled Steel Tubes With Hexagonal Shape After High Temperature And Fire

As a new type of structure,the hexagonal CFST is anewstructure.It can be connected with other components in a variety of ways,giving architects a wealth of design inspiration.Hexagonal CFST can also be designed into a honeycomb frame structure.At present,the research of related scholars in China mainly focuses on traditional components,such as rectangular and circular cross-sections,focusing on axial compressive bearing capacity,flexural bearing capacityandhysteretic performance.The hexagonal cross-section of the relevant discussion is relatively little.However,the test sample is less and the performance of other aspects of the component analysis is nothing.As a load-bearing structure,hexagonal CFST has not been reported in the study of its bearing capacity attenuation mechanism and post-disaster assessment after a building fire.In this situation,this paper focuses on the axial compression bearing capacity of hexagonal CFST after high temperature and fireand the distribution of temperature field under the action of fire.Through a large number of case studies and data processing,the formula for the load-carrying capacity of hexagonal concrete filled steel tubes after high-temperature heating has been fitted.The maintask are as follows:(1)Attenuation coefficient of hexagonal CFST after high temperatureUsing the finite element software to establish a numerical model for the unidirectional compression of traditional components after high temperature and comparing with the research results of the same type of scholars,a model of bearing capacity of axial load of hexagonal steel tube concrete under normal temperature was established and solved.The peak load capacity is compared with the relevant experimental data.It is verified that the model has the ability to simulate the performance of components after high temperature.A large number of data were used to fit the attenuation coefficient of the axial bearing capacity of the member after high temperature.(2)Temperature field of hexagonal CFST concrete in fireBased on the research results of thermal performance and mechanical parameters of steel tubes and concrete in the current academic circles,a temperature field analysis model for the traditional CFST in fire conditions was established.The analysis results were compared with those of the same type experimental data.Then they were extended to study the temperaturedistribution and working mechanism under the action of fire.(3)Attenuation coefficient of compression resistance of hexagonal CFST after construction fireThe finite element software was used to establish a numerical model for the uniaxial compression of traditional components after a fire and compared with the research results of the same type of scholars.After the reasonable model was verified,the finite element model of hexagonal CFST was established after fire.Study steel tube yield strength,concrete strength and temperature,etc.on the effect of fire on the hexagonal steel pipe concrete compression capacity attenuation coefficient.