UC San Diego

ABSTRACT: Reducing residual deformation or earthquake loads on the frame structure can enhance its seismic performance during ground motions. This study explores a novel system that uses a self‐centering brace (SCB) to provide the re‐centering capability of the frame and a sliding slab to reduce the system's acceleration. The floors are allowed to slide with respect to the re‐centering steel frame by adding low‐friction Teflon sheets, while various horizontal energy dissipating devices are used to enhance the seismic response of the frame. A self‐centering disc‐spring device is added to re‐center the slab after sliding in Phase 1. In addition to the spring device, a friction device in Phase 2 or a steel‐only sandwiched buckling‐restrained brace in Phase 3 is incorporated. The floor is “rigidly” connected to the frame in Phase 4, simulating a typical frame construction. Four phases, comprising 32 shaking table tests, were conducted on the specimen. A near‐fault motion record from the 2022 Guanshan and Chihshang earthquake was used. Phase 1 tests demonstrated that the SCB and horizontal disc‐spring device could fully re‐center both the frame and sliding slab at the maximum‐considered earthquake (MCE) level. In Phases 2 and 3, the addition of horizontal energy dissipating devices to the frame reduced slab movement but resulted in higher floor acceleration compared to Phase 1 tests. Compared to Phase 4, the effect of the sliding slab caused a roof drift reduction of 23% and 18%, and a base shear reduction of 15% and 5%, in Phases 2 and 3, respectively. Summary: A new steel system is evaluated by using self‐centering brace to provide the re‐centering capability of the frame and a sliding slab to reduce the system's acceleration. Evaluate the seismic performance by conducting 32 shaking table tests on the full‐scale, three‐story steel frame in four different phases. The sliding slab, equipped with SCSDs in parallel with horizontal energy dissipation devices (i.e., FD or H‐SBRB), reduced the seismic force on the frame compared to typical steel frames. The residual displacement of the frame specimen with the self‐centering brace is very small at an earthquake intensity close to two times the MCE level.