Enhanced Residential Building Code for Tornado Safety

Abstract

The EF5 tornado that occurred in Moore, Oklahoma on May 20, 2013, provided a rare opportunity to study the effects of multiple major tornadoes on a single community in a relatively short timeframe. Data collected immediately after the tornado indicate an ordered progressive collapse mechanism for residential wood-frame structures with slightly different progressions for low-pitch and high-pitch roofs. This failure progression indicates that a continuous load path from the roof to the foundation is the most important aspect of design and construction for tornado resistance of residential structures. Performance of homes in a neighborhood constructed using more-robust methods indicates that the damage path caused by an major tornado can be narrowed by improving the overall structural system with a series of relatively simple items. Twelve code modifications proposed by the authors to create a more-robust structural system intended to withstand winds up to