Evaluating community-level tornado losses and the cost–benefit of enhanced residential building codes: A case study of Moore, Oklahoma

On May 20, 2013, the Moore tornado devastated over 1000 residential buildings in the city. To reduce future tornado-related losses, 12 modifications to residential building codes were proposed and adopted by the City of Moore the following year. It is essential to determine if the expenses associated with modifications are worthwhile considering the potential savings from reduced tornado damage. Previous benefit-cost analyses are usually based on insured losses and fail to provide an accurate estimate of loss reduction attributable to enhanced construction. To achieve a more precise benefit-cost analysis, a tornado loss model was developed using a Monte Carlo simulation approach. This model includes tornado hazard modeling, the development of a tornado fragility function for both enhanced and unenhanced residential buildings, and local exposure information. The simulation result revealed that these modifications can mitigate expected community loss induced by tornadoes. Without considering the discount rate, the benefit-cost ratio (mitigated loss over retrofitting costs) is 0.88. The mitigated loss in this study only considers the house construction loss, and the benefit-cost ratio is expected to increase if house content loss, injury, and death loss are involved.