Evaluation of the variability contribution due to epistemic uncertainty on constitutive models in the definition of fragility curves of RC frames

In the framework of uncertainty propagation in seismic analyses, most of the research efforts were devoted to quantifying and reducing uncertainties related to seismic input. However, also uncertainties associated to the definition of constitutive models must be taken into account, in order to have a reliable estimate of the total uncertainty in structural response. The present paper, by means of incremental dynamic analyses on reinforced concrete frames, evaluates the effect of the epistemic uncertainty for plastic-hinges hysteretic models selection. Eleven different hysteretic models, identified based on literature data, were used and seismic fragility curves were obtained for three different levels of maximum interstorey drift ratio. Finally, by means of analysis of variance techniques, the paper shows that the uncertainty associated to the hysteretic model definition has a magnitude similar to that due to record-to-record variability.