Seismic Vulnerability Assessment of Masonry Residential Buildings in the Older Parts of Tehran through Fragility Curves and Basic RVS Scores

The present study aims to determine the Rapid Visual Screening (RVS) basic scores for four representative Unreinforced Masonry (URM) and their corresponding Confined Masonry (CM) buildings. Two types of analysis were carried out on the finite element models: modal and push-over analysis. It was observed that confining URM walls with horizontal and vertical RC ties leads to a significant improvement in both the ultimate strength and ductility ratio of URM buildings. The natural frequency and strength of the studied buildings were strongly influenced by the walls’ relative area. The push-over-based fragility curves indicate that there is an average of 100% increase in the spectral acceleration related to the 50% exceedance probability of the CP performance level of CM buildings compared to their corresponding URM buildings. Moreover, the average resulted RVS basic score of CM buildings was 45% higher compared to those of their corresponding URM buildings and their sensitivity to the higher seismicity of the region was lower, thus greatly reducing the vulnerability of masonry buildings.