Disproportionate collapse: a pragmatic approach

Abstract

Probability-based design methods face certain problems in making structures sufficiently collapse resistant and thus preventing disproportionate collapse. These problems are addressed and a discussion is given to outline how they might be overcome both within and outside a probabilistic framework. Definitions for the terms ‘robustness’ and ‘collapse resistance’ are proposed, the former being a property of the structure alone, the latter including possible causes of initial local failure. A pragmatic approach for designing against disproportionate collapse is suggested and a set of corresponding design criteria is presented. Design strategies based on preventing or presuming local failure are compared. In addition to the better-known design methods providing specific local resistance or alternative paths, an approach based on isolation by segmentation is examined. It is found that the applicability of the various design methods depends on the design objectives and on the type of structure.