Quasi-static and fatigue testing of earthquake-resilient steel joints with replaceable buckling-restrained links

This paper introduces the buckling-restrained concept into the design of traditional steel beam-column joints to improve the seismic and resilience performance. The upper and lower flanges of the beam are replaced by two buckling-restrained flanges (BRFs) to form a novel earthquake-resilient steel joint with a replaceable buckling-restrained link (RBRL). Four quasi-static tests and one fatigue test were conducted with various loading protocols, joint forms and core plate restraint systems. The experimental results, including the test phenomena, hysteresis curves (and the corresponding skeleton curves, energy dissipation capacity curves and stiffness degradation curves), and displacements and strains at the main positions of the specimens were obtained and analyzed. The test results show that the proposed joints exhibit an excellent performance in terms of hysteresis, fatigue and resilience, as expected. Comparative analysis results show that the loading protocols have an insignificant influence on the hysteresis curves before fracturing occurs. Additionally, the joint with a reduced section link is prone to instability and shows a lower energy dissipation capacity than the joint with the proposed RBRL, and when the compression gap in the restraint system is placed at the end of the core plate, the proposed joint behaves better.