Assessment of Potential Seismic Damage to Residential Unreinforced Masonry Buildings in Northern Illinois

Abstract

Ground acceleration estimates for northern Illinois are used to assess any damage that can occur to unreinforced masonry (URM) residential structures as a result of potential future earthquakes. These estimates are based on probable future activities in the New Madrid Seismic Zone and are published by the U.S. Geological Survey for exceedance probabilities equal to 0.10, 0.05, and 0.02 per 50 years. Accelerations corresponding to higher exceedance probabilities (1.0 and 0.25 probability in 50 years) are obtained from simplified seismic hazard analyses. Damage is estimated based on fragility curves available for URM buildings. The probability of damage is then used along with the inventory of buildings to arrive at estimates of the percentage and the number of buildings that may suffer damage of various levels (ranging from nonstructural damage to total collapse). The study shows that considering