Probabilistic seismic evaluation of SMA‐based self‐centering braced structures considering uncertainty of regional temperature

Abstract

AbstractSmart materials such as shape memory alloys (SMAs) have unique material properties that can potentially mitigate structural damage against earthquake. However, the mechanical behavior of SMAs is sensitive to temperature variation. The traditional deterministic analysis, which does not take into account the influence of temperature, may lead to inaccurate and sometimes unsafe predictions of actual behavior of SMA‐based structures. This research aims to develop a modified framework based on the performance‐based earthquake engineering methodology, taking account of the uncertainty of regional temperature distribution for temperature‐dependent (TD) structures, where the SMA‐based one is considered as a representative case. As the main part of the methodology, regional seismic fragility is generated by combing temperature distribution properties and joint seismic fragility. The proposed methodology is applied to a six‐story self‐centering concentrically‐braced frame (SC‐CBF) with SMA‐based SC braces located in different regions in China. A simplified thermo‐mechanical model capturing the TD characteristics and possible failure of SMA cables is utilized. Deterministic nonlinear static and dynamic analysis is first conducted to understand the structural response. Then, the joint seismic fragility analysis of the SC‐CBF under different intensity levels of ground motion and temperatures is conducted via the incremental dynamic analysis method, by which the seismic performance of the structure can be fully captured. Finally, the proposed methodology is utilized to comprehensively evaluate the regional seismic fragility and collapse risk of the SC‐CBF in different regions. The results indicate that the ignorance of the temperature effect could underestimate the risk of collapse.