Innovative Self-Centering Braces for Advanced Seismic Performance

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Buckling-restrained braces are currently being used as primary lateral-force resisting elements for buildings in high seismic regions. After strong ground shaking buildings containing buckling-restrained braces are likely to be permanently deformed and thus their repairs may not be feasible. Since it is desirable to develop structural systems that self-center and have no permanent deformation, this project will investigate the use of innovative self-centering buckling-restrained braces as seismic protective devices in buildings. The proposed self-centering buckling-restrained brace consists of a novel configuration of steel tubes and anchorage plates installed with super-elastic shape-memory alloy rods to provide a self-centering mechanism with predictable and stable energy dissipation. The primary objective of the proposed research is to conduct experimental and numerical studies that establish a sound basis for application of the proposed protective system in practice. Large-scale prototype self-centering buckling-restrained braces will be tested to verify the anticipated brace behavior and to examine the effect of critical brace parameters. Numerical models will be developed and validated for use in parametric component studies and braced frame earthquake simulations. The results from the experimental and numerical studies will be used to develop design and fabrication guidelines for practical implementation of self-centering buckling-restrained braces in earthquake-resistant structural systems.The use of the proposed self-centering buckling-restrained brace system has the potential to significantly limit earthquake damage and economic loss in building structures. The proposed protective system can be easily substituted for conventional steel braces or buckling-restrained braces, and this ease of use will make it especially attractive to practicing engineers and contractors. The use of self-centering buckling-restrained braced frame systems, which can be designed to withstand large earthquakes with little to no damage, has the potential for significant broader impact on earthquake affected communities by providing buildings with immediate occupancy performance. This project will also provide unique learning opportunities and training to undergraduate and graduate students as they actively participate in the development of this advanced protective system.