Risk assessment of confined unreinforced masonry buildings based on FEMA P-58 methodology: a case study—school buildings in Tehran

Abstract

Seismic performance of a representative single-story confined unreinforced masonry school building in Tehran, Iran is evaluated by means of incremental dynamic analyses according to FEMA P-58 framework. For this purpose, fragility curves are derived for each of the constituent walls of the building. The in-plane behavior of the walls is considered only. Both flexible and rigid diaphragm conditions are investigated. For comparison purposes, the corresponding unconfined building exactly duplicating the considered confined unreinforced masonry building is also studied. In order to analyze the effects of near-source seismic actions on the performance of masonry buildings, two separate far-field and near-field ground motion sets containing 326 records are used. By utilizing the results of the incremental dynamic analyses and the available data of unreinforced masonry school buildings in Tehran, a scenario-based risk assessment of this type of school buildings is performed considering all three adjacent faults for three different earthquake magnitudes. Considerable performance improvement is achieved by providing confinement to the walls which leads to over $100 million reduction in the damage costs for masonry school buildings in Tehran. Also, significant reduction in seismic vulnerability, especially for unconfined masonry buildings, is observed by providing the roof with more rigidity. The findings in this study can be of direct use for disaster management of masonry school buildings in Tehran and similar cities.