Fragility curves for reinforced concrete frames characterised by different regularity

This paper presents a comparison between fragility curves developed for regular and non-regular reinforced frames. Three 3D reinforced concrete multi-story frames characterised by different regularity are analysed. These fragility curves are developed through the “Cloud Analysis“ procedure, which evaluates the structural response via Non-Linear Time History Analysis (NLTHA). Both maximum inter-story drift and maximum chord-rotation demand/capacity ratio are used as Engineering Demand Parameters, in which the chord-rotation capacity is calculated according to the Italian Code. To fully develop the fragility curves, both structure-independent and structure-dependent scalar intensity measures are selected among the most referred in practice and literature. This work shows the influence of regularity on the damage levels of the three buildings. Furthermore, it shows the uncertainties caused by the selection criteria for EDP thresholds, which are necessary for a correct representation of the Limit State.