Simulation-Based Fragility Relationships for Unreinforced Masonry Buildings

Unreinforced masonry (URM) structures represent a significant portion of the residential building stock of the central and eastern United States. Fifteen percent of homes in the eight-state region impacted by the New Madrid Seismic Zone are URM buildings. The brittle nature of URM buildings further supports a thorough consideration of seismic response given the susceptibility to severe failure modes. Currently, there is a pressing need for analytically based fragility curves for URM buildings. To improve the estimation of damage-state probabilities through the development of simulation-based URM fragilities, an extensive literature survey is conducted on pushover analysis. Using these data, capacity curves are generated, from which damage performance limit states are defined. Demand is simulated using synthetically derived accelerograms representative of the central and eastern United States. Structural response is evaluated using an advanced capacity spectrum method. Capacity, demand, and response are thus derived analytically and utilized to generate a more reliable and uniform set of fragility curves for use in loss-assessment software. This paper presents a framework amenable to rapid, flexible updating that, with the appropriate database of studies, is capable of producing curves representative of any URM building typology subjected to a specified hazard. The curves are expressed in multiple forms to demonstrate capability of use in various loss-assessment applications.