Comparative Residential Property Loss Estimation for the April 25–28, 2011, Tornado Outbreak

Abstract

The largest tornado outbreak in the United States occurred on April 25–28, 2011. The outbreak resulted in widespread destruction across the southeastern United States and was responsible for over $5 billion in property loss. Although tornadoes cause significant damage every year in the United States, they are not currently included in building codes because the annual likelihood of an individual building being struck is quite small. However, catastrophic damage following large-scale tornado outbreaks has resulted in inquiry into the benefit of the use of stricter wind-design provisions in residential construction. Using the results of a fragility analysis based on the performance of a wind-induced vertical load path, property loss to wood-frame residential construction from tornadoes was estimated for residential buildings designed using locally adopted building codes at the time of the outbreak. The analysis was performed a second time, but this time using the stricter wind provisions of a state residential code applied across a portion of the southeastern United States. This allowed for an estimate of the reduction of property loss to wood-frame residential construction from large tornado outbreaks by using strengthened construction methodologies. Results indicate a reduction in residential property loss of up to 40% for the April 2011 outbreak.