Fragility curves for different intensity measures for a gravity load-designed RC hospital building: A case study

Abstract

An awareness of the vulnerability of strategic facilities such as hospital buildings is essential to manage post-earthquake events in seismic areas and to plan the allocation of funds for ensuring not only their capacity versus collapse, but also their functionality immediately after seismic events.Fragility functions represent an important scientific approach in the vulnerability assessment procedures for existing building stocks, and the consequent mitigation of seismic risk. It is worth noting that most of the literature on Fragility Curves (FCs) refers to building stocks, but to analyse a considerable number of structures it is often necessary to use simplified building models. The rare discovery in the technical offices of the hospital of very detailed as-built drawingshas allowed for modelling as much as possible adherent to the actual building. The purpose of this work is to provide multiple sets of FCs for a complex reinforced concrete hospital building designed only for gravity loads. These sets can represent a useful tool for the validation of similar structures, which cannot always be traced back to simplified cases. Furthermore, FCs are evaluated for five different Intensity Measures (IMs) to determine the best choice for this parameter. Peak Ground Acceleration, Spectral Acceleration corresponding to the fundamental period of a structure (both intact and damaged), Housner Intensity, and the Geometric Mean of the Spectral Acceleration between 0.2T1 and 3T1 are chosen as different IMs.Incremental Dynamic Analyses are performed on a three-dimensional model to evaluate the FCs for four damage levels. The results are then compared, showing that four out of five intensity indices give consistent results.