A simplified analytical methodology for fragility curves estimation in existing buildings

Seismic risk assessments are mostly based on fragility curves. In regions with moderate seismicity, these curves are determined though the extrapolation of the empirical fragility analyses established in other parts of the world. Hence, fragility curves should be improved considering realistic structural models. There is a lack of improvements, especially in regions with moderate seismicity due to low perceived seismic hazard. Therefore, an advanced methodology is proposed in this paper for the study of unreinforced masonry buildings (URM), common in North Western Europe. An existing analytical displacement-based methodology is improved, in order to better estimate capacity curve, fundamental period, displacement shape and damage grade definitions. Moreover, a probabilistic framework is proposed to determine fragility curves. Using the proposed methodology, an existing multi-storey URM building is analysed. Its seismic behaviour and the assessment of the first damage grades are compared to ambient vibration measurements.