Risk-targeted seismic design for collapse safety of SMA-based structures considering temperature effect

A risk-targeted seismic design method for shape memory alloy (SMA)-based structures is proposed in this study, taking account of temperature effect and the uncertainty of regional temperature distribution. To facilitate discussion of the overall performance of SMA-based structures, the thermo-mechanical behaviors of both SMA material and SMA-based self-centering braces (SMA-SCB) are first introduced, where an advanced simulation method is developed. Aided by an extensive parametric study, the collapse capacity of SMA-based structural systems is comprehensively investigated, where the predominant factors controlling the seismic performance are revealed. Based on the results, the concepts of collapse capacity-temperature function and temperature-modified collapse capacity are introduced in this study. The temperature-modified collapse capacity combines the information of regional temperature distribution and temperature-dependent behavior of the SMA-based structures. The temperature-modified collapse capacity is developed to determine the risk-targeted design spectral acceleration for satisfying the specific risk-targeted performance objective. The procedure of the proposed design method is then demonstrated by examining a three-story SMA-based self-centering braced frame (SMA-SCBF) building in a selected seismic-active region, followed by a probabilistic method to evaluate the collapse risk. The results manifest that by using the proposed design method, the SMA-based structures can successfully achieve acceptable performance during the design service life, and the influence of temperature should be carefully taken into consideration in both assessment and design phases.