Design Guidelines for Community Shelters for Extreme Wind Events

Abstract

The design of shelter structures has received little attention from the engineering community since the days of nuclear fallout shelters, until the development of guidance for community shelters for cases of extreme wind events was released by FEMA in July 2000 (FEMA 361). To respond to the recent demand for community shelters, many states are designating existing schools or other public buildings, such as community centers or multipurpose buildings, as public shelter areas. In most cases these buildings, or portions of these buildings, were never designed for use as shelters. Most of the designated shelters were designed and constructed according to older local building codes that do not include requirements for extreme wind pressures and uplift. Even recently designed structures have been found to have inadequate features for a high-wind shelter, particularly with respect to cladding and architectural features that are vulnerable to damage from high winds and windborne debris. Damage to the cladding is often the beginning of building failure and occupant injury during an extreme wind event. This paper identifies critical issues and gaps in presently available technology for evaluating proposed shelters and providing retrofit guidance to building owners. The writers’ experience with inspections of designated shelters, proposed retrofit recommendations, and damage investigations of buildings affected by hurricanes or tornadoes is summarized. Recommendations for design considerations that include the current standards of practice as outlined in FEMA 361, ASCE 7-98, and the Florida Shelter Evaluation Guidelines are given.