Seismic performance and risk assessment of self-centering steel braced frames considering failure of prestressed tendons

This paper comprehensively discussed the performance of self-centering steel braced frames suffering failure of prestressed tendons. The performance of the structures with shape memory alloy (SMA) cable-based self-centering braces was also examined. Through theoretical analysis, the fundamental mechanism of tendon failure of typical single core and dual core self-centering braces is first introduced, and it is found that the dual core self-centering brace may suffer more abrupt failure, although its deformability is improved. Four prototype structures were designed, i.e., an ideal self-centering braced frame without considering the failure of prestressed tendons, single core and dual core self-centering braced frames considering the failure of prestressed tendons, as well as an SMA-based self-centering braced frame. Considering a random distribution of tendon failure strain, nonlinear time history analysis was carried out on the frames under far-field and near-field earthquakes. Furthermore, the collapse and residual deformation fragilities of the frames were evaluated, and risk assessment was conducted according to the site characteristics. The results show that the risk of collapse is significantly increased when considering the failure of the prestressed tendons. During their service life, the collapse probability is about five times that of the ideal case and the probability of exceedance of residual deformation is up to six times that of the ideal case when tendon failure is considered. The SMA self-centering brace has enhanced deformation capacity and enables additional energy dissipation, and hence performs better in mitigating both the risk of collapse and residual deformation. © 2022, Editorial Office of Journal of Building Structures. All right reserved.