Performance-based plastic design approach for multi-story self-centering concentrically braced frames using SMA braces

Self-centering concentrically braced frames (SCCBFs) are emerging as one of the high performance seismically resistant framing systems, known for the capability of controlling peak seismic demands and eliminating residual deformation. In the process of developing SCCBFs, shape memory alloys (SMAs) are deemed as the potential candidate for the key component of SCCBFs, due to the excellent superelastic capacity and desirable flag-shape hysteresis. For the SCCBFs using SMA braces (SMABs), an economical and effective design approach based on the performance-based plastic design was recently derived. This study aims to extend the ad hoc design approach to low-to-high rise multi-story SCCBFs using SMABs, and to examine its generality. As such, the seismic performance of four SCCBFs with various story numbers was intensively analyzed by subjecting them to ground motion records corresponding to design-basis earthquake. The analysis results show that all the resulting frames were capable of coinciding well with the prescribed targets of peak interstory drift ratios and ductility demands. In addition, the structures returned to at-rest positions without producing residual deformation after earthquake events. Therefore, this study successfully validates the applicability of the ad hoc design approach to SCCBFs with various story numbers.