Performance of Residential Shelters during the May 20, 2013, Tornado in Moore, Oklahoma

Abstract

Residential shelter performance, in the aftermath of the devastating May 20, 2013, EF5 tornado that struck Moore, Oklahoma, was investigated by a reconnaissance team comprised of researchers from several universities. The team observed and documented 75 residential shelters along the tornado damage path and noted that the concept of shared shelter use was responsible for saving many lives. All belowground shelters performed well with no evidence of structural compromise or shelter breach from debris missiles; however, debris was occasionally observed blocking the opening of the garage slab residential shelters and flooding was also noted in a few cases. Although less common, the majority of above ground residential shelters observed were found in areas that experienced EF3–EF4 estimated wind speeds. In all cases but one, the above ground safe rooms performed well. A debris missile breach of an insulated concrete form (ICF) safe room was documented. While poor construction quality, specifically poor concrete consolidation in areas where plastic cross-ties held the form together, was found to be the major contributing factor in this failure, other factors such as safe room placement within the house and the type of missile (thin-walled steel square tubing) also contributed to this failure.