Research On Fire Performance Of Restrained PEC Column-composite Beam Connections

Column-beam connections play a crucial role as an important part of the frame structure to maintain structural safe performance in fire. That the fire resistance performance of the connection is an important basis for the anti fire transition from component to the structure. Now the the anti fire study of partially encased concrete columns(PEC columns) to beam connections in fire is not reported. Restrained PEC columns-composite beam connections(about the strong axis) are chosen as the research objects. The fire performance and the relationship of moment-rotation-heating time are studied.The main research work includes:1. After determining the thermal parameters and constitutive relation model of steel-concrete composite connections under fire, the finite element method is applied to simulate thermal and structural coupling response of composite connections exposed to fire. It is by comparing the results obtained from the test and finite element analysis that verified the rationality of the model.2. The temperature distributions, failure modes, deformations,stress and strain distributions of the restrained PEC columns-composite beam connections(about the strong axis) under the combined loads and fire including heating phases were analyzed using the theoretical model which verified.3. The angle of joints were analyzed, including influences of axial restraint stiffness, load ratios of column and beam, beam-column geometric parameters.4. Influences of parameters, such as axial restraint stiffness, load ratios of column and beam, beam-column geometric parameters, were analyzed for discussing the above parameters of the fire resistance. After analyzing of the above parameters of the fire resistance results, a simplified formula for the calculation of fire resistance was put forward.5. The influences of the fire duration time, axial restraint stiffness, load ratios of column, beam-column geometric parameters,the moment versus rotation angle relations of the connections were discussed. Simplified formulas for calculating the moment –rotation relationship under fire of the joints were proposed.