Experimental Research on Seismic Performance of Prefabricated CFST Composite Column-Reinforced Concrete Beam Joints

In order to study the seismic performance of prefabricated joints in underground space structures, a new type of prefabricated CFST composite column-reinforced concrete beam joint was designed and fabricated and compared with the cast-in-place CFST composite column-reinforced concrete beam joint. Quasi-static load tests were conducted on two types of joints. The hysteresis curves, skeleton scurves, stiffness degradation curves, energy dissipation capacity, ductility, and other indicators of the two types of joints were compared and analyzed. The results showed that both types of joints were subjected to bending failure in the plastic hinge area of the beam end and the ultimate displacement of the assembled joint was 47.6% higher than that of the cast-in-place joint, but the difference in ultimate bearing capacity between the two joints was not significant. The stiffness of the final joints was reached failure by about 10% of the initial stiffness, and the joints underwent significant nonlinear deformation and damage. The final cumulative total energy consumption of cast-in-place and prefabricated joints reached 35.69 kN·m and 58.77 kN·m, respectively. The prefabricated joint was greater than that of the cast-in-place joint, which was 1.65 times the cast-in-place joint. The yield and ultimate displacement of the prefabricated joint had increased by 30.68% and 32.47% respectively compared with the cast-in-place joint. The difference in yield and ultimate load between the two types of joints was not significant, and the ductility coefficients of prefabricated joints was slightly higher than cast-in-place joints. The ductility of the prefabricated joint was better than the cast-in-place joint.