Study On Hybrid Fire Testing Method For Multi-layer Steel Frame Structure

At present,the response of structural fire loads is usually studied under a constant boundary condition with a single component fire test.This test method is relatively easy and economical,but the boundary conditions cannot be consistent with the real situation.The overall structural fire resistance test is another method to study the fire resistance of the structure.The method takes into account the real boundary conditions and the results are relatively accurate,but the cost is too high.The hybrid fire testing method combines the advantages of the single component fire resistance test method and the overall structure fire resistance test method,and divides the overall structure into a numerical substructure and a physical substructure,and performs a real fire test on the test substructure while considering the constraint effect of the surrounding components.The numerical substructure is numerically simulated using large finite element software.The mechanical balance and boundary coordination are satisfied by the boundary conditions and data exchange between the physical substructure and the numerical substructure.Make full use of the existing test equipment to complete the overall structural fire test by considering the substructure test method of the constraint condition,and obtain a more reliable overall structure fire resistance performance.The main contents of this paper are as follows:(1)A brief introduction to some basic theoretical knowledge in structural fire resistance analysis.On the one hand,the basic principles of heat transfer and thermal parameters of materials are introduced.Different parameters are selected and applied to the analysis of fire resistance performance.On the other hand,the basic principle and data conversion of the hybrid fire testing are introduced,and the hybrid fire testing is compiled.The basic steps of the test lay the foundation for the study of structural fire resistance performance.(2)Using the finite element analysis method to simulate the hybrid fire testing process.Taking the steel frame as the whole structure,the middle column is selected as the physical substructure,and the remaining part is the numerical substructure.The hybrid fire testing is carried out.The boundary conditions of the control substructure are interacted in real time during the test,and the control structure is in the test process.Balance and coordination.Verify the feasibility of the hybrid fire testing.(3)Study the applicable conditions of the hybrid fire testing method.The boundary conditions of the physical substructure and the numerical substructure in the hybrid fire testing include constraints and interface conditions.The substructures are divided into four cases according to the number of constraints,and the hybrid fire testing is carried out separately to better understand how the number of constraints affects the hybrid fire testing process.(4)Study the damage of the overall structure when fired in different areas.The hybrid fire testing method is applied to the multi-layer steel frame,and the fire area is divided into six areas.The damage of the steel frame structure in the case of fire in different areas is studied,and the results are analyzed,Contrast,the impact of fires on the overall structure in different areas is obtained.