Fragility Analysis of 3D Reinforced Concrete Frames Based on Endurance Time Method with Derived Standard Deviation

Abstract

Fragility curves have been developed for seismic vulnerability analysis of structures and can be generated in empirical and analytical forms. To develop analytical fragility curve, the incremental dynamic analysis (IDA) method is considered as an applicable tool for seismic analysis; however, in the cases with high modeling complexity, the computational cost of the IDA method may be very high. Therefore, an alternative method called as endurance time (ET) method can be effectively used for fragility analysis. In this study, a new, accurate and cost effective method has been introduced in order to develop analytical fragility curves based on the ET method. The results reveal that ET-based fragility curves generally agree well with IDA-based fragility curves. In addition, it is revealed that a highly matched fragility function can be fitted on fragility points using ET-based fragility analysis (due to continuity of these points in every 0.01 of IM changes). It is concluded that ET analysis offers convenient and easy access to median and logarithmic standard deviation of IMs and thus fragility function can be produced easily based on these statistical parameters. Furthermore, a new ET-based methodology is presented to consider the previously experienced earthquakes (PEEQs) in generating fragility surfaces.