Seismic evaluation of industrial steel moment resisting frames with shape memory alloys using performance-spectra-based method

Seismic evaluation of industrial facilities may need to employ multi-performance indicators in various yielding stages towards a more delicate design methodology. This paper develops a performance-spectra-based method to evaluate the seismic performance of industrial steel moment resisting frames (MRFs) with shape memory alloys (SMAs) considering multi-performance indicators and hysteresis transition. The work commences with demonstration of the hysteresis transition of a steel MRF with SMAs from the ‘self-centring stage’ to the ‘post self-centring stage’. Then, based on the single-degree-of-freedom (SDOF) analogy and the hysteretic model considering hysteresis transition, a performance-spectra-based space for quantifying the seismic behaviour of an industrial steel MRF with SMAs including multi-performance indicators is established. In this study, the performance-spectra-based space employs three essential indicators (i.e. energy modification factor, peak acceleration ratio and residual displacement ratio). To demonstrate the application and validate the adequacy of the proposed method for seismic evaluation of industrial steel MRFs with SMAs, two prototype steel MRFs equipped with SMA connections for industrial use are designed and assessed under representative earthquake ground motion ensembles. By comparing essential structural seismic response quantities (i.e. maximum roof displacement, peak interstorey drift ratio, peak floor acceleration and interstorey residual drift ratio) predicted by the proposed method with those calculated by nonlinear-response-history analyses (NL-RHAs), the effectiveness of the proposition is confirmed.