Progressive-Collapse Loads for Flat-Roof Structures

Abstract

Progressive collapse was defined as “the widespread propagation of failure following damage to a relatively small portion of the structure,” by Breen in 1975. Existing quantitative approaches to prevent progressive collapse are reviewed and are seen to be limited to floor and wall structures. Those recommendations are extended to develop a design equation for roof structures on which snow loading needs to be considered. The statistical characteristics of roof snow loading are reviewed, and a load and resistance factor design equation is developed for the alternate path analysis of flat-roof structures subject to snow loading.