9634560 Murtha-Smith Progressive collapse is a catastrophic mode of failure started by localized damage occurring at operating loads. The objectives are to investigate the role of each nonlinear member in a progressive collapse mechanism, explore the role of secondary effects in the survival of damaged DLG systems, correlate linear and nonlinear AP analyses to determine if linear analysis can be used to predict performance and be used for design, develop a method that can rationally modify a design using the linear AP method to improve progressive collapse resistance. ***