Comparison of IDA and multicomponent IDA-based fragility analysis

Abstract The results of the fragility analysis of important structures depend on the accuracy of structural analysis. Incremental dynamic analysis (IDA) and multicomponent IDA (MIDA) are commonly-used structural analysis methods for the seismic assessment of structures. The present paper aims to evaluate the seismic performance of a structure with high seismic vulnerability using IDA and MIDA-based fragility analysis. A numerical model was used to model a typical wharf. Next, Pushover analysis, IDA, and MIDA along randomly-selected incident angles were performed. The results of each analysis were converted to a response surface by extrapolation. The response surface presented the zones, which included the critical responses. The difference between the response surface of MIDA and IDA at the global instability was approximately 38%. Further, the fragility surfaces of IDA and MIDA results were developed. The critical zones presented by MIDA and IDA fragility surfaces were not identical, particularly at the serviceability limit state. There was a difference of 11% and 20% between MIDA and IDA fragility surfaces, where the responses exceeded the reparability and near collapse limit state, respectively. The results showed that implementing the developed form of IDA (MIDA) could optimize the input data of fragility analysis for structures with high seismic vulnerability.