Abstract:
The suspended ceiling system (SCS) experienced obvious damage during earthquakes in recent years, and the failure of the main-cross tee joints is one of the major reasons for the ceiling damage. A series of tests on main-cross tee joints under monotonic and cyclic loadings were conducted to investigate the shear and bending behaviors of the main-cross tee joints. The failure modes, load-bearing ability, deformation capacity, hysteretic behavior, and energy dissipation capability of the joints were investigated, and the fragility curves of the joints were established. The test results indicate that the failure modes of the main-cross tee joints in the strong and weak axes under shear loading are the shear failure and out-of-plane bending and separation failure of the joints, respectively. The brittle separation from the grid is the failure mode of main-cross tee joints under bending loading. Compared with the shear capacity of the joints in the strong axis, the joint strength is lower but the deformation ability of the joints is stronger in the weak axis in the shear test. Compared with the bending capacity of the joints in the strong axis, the joint strength is greater but the rotation ability of the joints is slightly lower in the weak axis in the bending test. Whether under bending or shearing loadings, the pinching effect of the load-displacement hysteretic curve of the joints is significant, and the energy dissipation capacity is limited. The fragility analysis shows that the main-cross tee joint is more vulnerable when the weak axis of the joint is subjected to a shear force or the strong axis of the joint is subjected to a bending moment.