The Research Of The Fire Resistance Performance Of The Joint Of CFST Column And Steel Beam

Due to the combined advantages of higher bearing capacity, excellent fire-proof performance and better seismic resistance, the concrete filled steel tube composite structures has become more and more widely applied to architectural structures. Among all the parts in the structures, the composite joint is a crucial one to their mechanics performance. As there is little study on the mechanical property of stiffener ring joint in high temperature, so it is necessary to do some more further research in this field. This article adapts the dead load heating method to investigate the fire resistance behavior of the joint of CFST column and steel beam in the case of fire. The contents of the job mainly include the following several aspects:(1) By employing proper steel and core concrete thermal parameters under fire as well as thermal boundary condition and fire scenario, the paper has established a fire-temperature field model of the joint of CFST column and steel beam via the finite element software ABAQUS. The node section temperature field in different moments is obtained, which is in good agreement with the experiment, thus illustrating the availability and the validity of the FEM model.(2) On the basis of selecting the proper constitutive relations of steel and core concrete and boundary conditions under normal and high temperature as well as the reasonable division of division of the grid, the FEM model of the CFST column-steel beam joint under fire is then built. The effective simulation has achieved a satisfactory result on the analysis of the fire resistance duration and the critical temperature of the joint in high temperature.(3) Influences of different parameters on the joint fire-proof performance have also been studied in this paper. This part of the paper mainly includes two aspects: influences of different parameters on the fire resistance limit and the failure patterns of the stiffener ring joint under fire. The major parameters are loading ratio> steel proportion、n axial load ratio、the thickness of steel tube in core zone、the strength of concrete and the beam section height, etc.