Although conventional earthquake-resisting structural systems provide adequate life safety when properly designed, they often rely on significant structural damage to dissipate the seismic energy. The structural damage and the residual drift that may result from the inelastic response can make a building difficult, if not financially unreasonable, to repair after an earthquake. As a result, development of systems that return to their initial position (i.e., ???self-center???) following an earthquake and minimize structural damage is a crucial need. The research presented in this thesis aims to address this need by creating an innovative self-centering brace for advanced seismic performance.
In the present study, the seismic behavior and performance of self-centering buckling-restrained braces (SC-BRBs) using shape memory alloys (SMAs) is investigated. The SC-BRBs consist of a typical BRB component, which provides energy dissipation, and pre-tensioned superelastic NiTi shape memory alloy rods, which provide self-centering. The SMA rods are attached to the BRB portion of the brace using a set of concentric tubes and free-floating anchorage plates that cause the SMA rods to elongate when the brace is both in tension and compression. Using a five-story building as context, half-scale SC-BRBs are designed and fabricated for experimental validation. To characterize hysteretic response, the braces are subjected to a cyclic loading protocol adapted from the AISC Seismic Provisions for Structural Steel Buildings. The results of the experiments are used to validate an SC-BRB model in OpenSEES, which is used to conduct further parametric studies of SC-BRB behavior
