Fragility assessment of existing low-rise steel moment-resisting frames with masonry infills under mainshock-aftershock earthquake sequences

Abstract This paper presents the fragility assessment of non-seismically designed steel moment frames with masonry infills. The considered effects multiple earthquakes on damage accumulation frames, which is an essential part modern performance-based earthquake engineering. Effects aftershocks are particularly important when examining damaged buildings and making post-quake decisions, such as tagging retrofit strategy. procedure proposed in present work includes two phase assessment, based incremental dynamic analyses refined numerical models case-study frame, i.e. without infills, utilises mainshock-aftershock sequences natural records. first focuses undamaged structure subjected to single earthquakes; infills seismic vulnerability frame were also considered. In second phase, aftershock curves derived investigate infilled post-mainshock caused by mainshocks. Comparative conducted among mainshock-damaged structures considering three levels, including no damage. impact was then discussed for each mainshock-damage level terms breakpoint that marks onset exceeding level, well probability superior due more significant aftershocks. evaluation efficiency commonly used intensity measures carried out assessment.