Post-fire Load-carrying Properties of a Reinforced Concrete Beam Supporting Column Transfer Structure Joint Unit

According to the characteristics of a reinforced concrete beam supporting column transfer structure, two types of full-size beam supporting column transfer structure joints are designed, and the post-fire residual mechanical behavior is tested. We observe the deformation and crack propagation of joint specimens under load, construct the load-deflection curve, record the post-fire residual strength and analyze the failure mode. The results show that longer exposure to high temperature is correlated with a smaller residual capacity of the joint units. When the specimens reach the ultimate bearing capacity, cracks form in the A-type joint unit specimens that are aligned with the central axis of the supported column, and several vertical cracks appear in the core area of the joint. The cracks of the B-type joint unit arise primarily on the compression side of the supported column, and many prominent inclined cracks arise in the core area of the joint that extend from the bottom to the compression zone of the transfer beam. Therefore, for structures with a bearing column girder transfer floor, the influence of the change of the internal force distribution on the post-fire load-bearing performance caused by the arrangement of the column should be considered.