Risk-targeted Maps for Spain

Abstract

Many studies have demonstrated that the design of structures in the region through the uniform hazard principle does not guarantee the uniform collapse risk. Even in those regions with similar PGAs corresponding to the same mean return period, the seismic risk in terms of failure probability will be significantly different due to the structural capacity uncertainty. In this paper, the newly introduced method, known as risk targeting, is being explored in Spain using the recently updated seismic hazard map. Since risk targeting involves multiple input parameters such as model parameters of fragility curves, their variability is considered through their probability distribution corresponding to the RC moment frame building, which is the most common typology in Spain. The influence of variation of these parameters on the risk results are investigated and different assumptions for estimating the model parameters of fragility curves are illustrated. These assumptions are included in a fixed fragility curve (generic) or building-site-specific fragility curves. Different acceptable risk levels (i.e., collapse and yielding) were considered concerning the Spain seismicity level. Finally, the maps for risk-targeted design ground motion and risk coefficient are presented. It was outlined since the shape of the hazard curve across Spain is different and considering the uncertainty of structural capacity; the employment of risk-targeted analysis led to the modifications for existing design ground motions. Moreover, it was found that using the building- and site-specific fragility curves could provide better results.