Study on fire resistance of high performance concrete nonplanar beam-wall joints

The utilization of high performance concrete (HPC) in the core region of beam-wall joints can enhance the structural integrity and load-bearing capacity of prefabricated buildings. However, due to the high-temperature bursting characteristics of HPC, the mechanical properties of the joints degrade prematurely under fire. In this paper, the fire resistance of HPC nonplanar beam-wall joints was investigated using high-temperature experiments and numerical simulations. First, the prefabricated beam-wall joint and the cast-in-place beam-wall joint proposed in this study were subjected to high-temperature and post-fire static loading tests, enabling a comparative analysis of their fire resistance and load-bearing capacity. The results demonstrated that the utilization of HPC in the core region of the prefabricated beam-wall joints can enhance its load-bearing capacity and fulfill the fire resistance requirements. Subsequently, a finite element model of the nonplanar beam-wall joint was established based on test results to investigate the influence of different structural parameters on its post-fire mechanical properties. The results demonstrate that the diameter of vertical reinforcement in the wall can significantly influence the post-fire load-bearing capacity of the joints, while the concrete strength in the core area of the joints has little impact on the post-fire bearing performance of the joints. Compared to the conventional cast-in-place beam-wall joints with normal strength concrete, the prefabricated beam-wall joints have superior fire resistance and post-fire load-bearing performance.