Seismic performance of demountable diagonal connection RCS joints: Experimental and theoretical study

This study proposed demountable diagonal connection joints consists of Reinforced Concrete columns and Steel beam (RCS) joint with the slab and systematically analyzed its seismic performance through cyclic loading tests. The investigation focuses on the effects of different steel beam flange thicknesses and concrete strengths on key seismic indicators, including hysteretic curves, stiffness degradation, energy dissipation, and ductility. The experimental results demonstrate that the joint with the slab outperforms traditional casting joints in terms of stiffness degradation, energy dissipation capacity, and ductility coefficient. The joint exhibits excellent hysteretic behavior within a drift ratio range of 0.5 %-2 %. Compared to the cast-in-place joint, the demountable specimens achieved improved energy dissipation and comparable deformation capacity while enabling post-loading disassembly without major damage. Additionally, a formula for calculating the initial rotational stiffness of the joint is proposed using the component method, with the calculated values closely matching the experimental results.