| At present,there are two methods to study the fire resistance of structures at home and abroad.One is the whole structure fire test,the other is the individual component fire test.However,the whole structure fire test has high cost,high cost and poor versatility,which requires high test equipment.However,the individual component fire test is carried out under constant boundary conditions,which can not reflect the mechanical properties of the component in the whole structure.Therefore,this paper introduces a new method to study the fire resistance of structures: hybrid fire test method.The principle of the hybrid fire test method is to divide the whole structure into two parts: one part of the fire components with strong nonlinear response is used as the test substructure for physical loading,and the rest of the structure is analyzed by finite element software.The force balance and displacement coordination at the interface of substructure segmentation are satisfied by the data interaction of boundary force and displacement.However,the boundary conditions of the test substructure are often complex.The fire resistance hybrid test method simplifies the boundary conditions of the test substructure by means of data conversion,which not only considers the existing test conditions,but also fully considers the restraint effect of the surrounding members on the fire members.The main contents of this paper are as follows:（1）Under the guidance of the fundamental principle of heat transfer,the appropriate constitutive models at high temperature is selected to analyze the fire resistance of the structure.Based on the basic theory of hybrid fire test,the conversion process of equivalent component and actual component of hybrid fire simulation with columns and beams as substructures is summarized.（2）The boundary of the test substructure is extended to the upper column and the reverse bending point of the beams on both sides,researching a four-story and four-span reinforced concrete frame.The different restraint effects of the upper structure on the fire members can be fully considered,and the whole structure,the traditional fire column and the hybrid simulation model are established respectively considering the fire conditions of the side column and the middle column.The mechanical properties of the three models are compared to verify the feasibility of the fire resistance test method based on the restrained column structure.（3）It can only be applied to the bottom area under fire,fully considering the limitations of the hybrid fire test method based on constrained column structure,,while the boundary conditions of the segmentation method of the substructure under fire in the upper area are complex and not applicable.Furthermore,the feasibility of hybrid fire test method with different test units as test substructures is studied.（4）Two methods are used to establish the mechanical properties and geometric damage models of seismic materials.One is to input seismic waves for dynamic elastic-plastic analysis.One is to establish a damage model considering cracks,spalling and residual deformation.The fire resistance hybrid simulation method based on constrained column structure is used to explore the feasibility of fire resistance hybrid simulation method after earthquake damage.（5）The chapter assumes that the fire occurs in six different areas of the frame,taking a single fire column as the test substructure,the fire resistance performance of the structure under different fire conditions in different areas is studied by using the hybrid fire simulation method,which fully reflects the restraint effect of different fire areas in the whole structure. |
