Designing a structure to reduce the likelihood of disproportionate collapse requires an understanding of structural and material behavior and the expected response of that particular structure to the loss of a selected portion of the vertical load-resisting system. Alternative Load Path (ALP) Analysis is one commonly accepted method used to assess whether the structure is vulnerable to disproportionate collapse. If the results of the ALP analysis indicate that the structure is vulnerable, the practicing structural engineer can take steps to improve the robustness of the design until acceptable levels of alternate load paths are achieved to alleviate the potential for disproportionate collapse.
Chapter 2 of the Alternative Load Path Analysis Guidelines, currently in development, provides an overview of alternative load path analysis and its application to various structural types and systems for buildings. It also includes a summary of some commonly used codes and standards in relation to ALP analysis that a practicing structural engineer may encounter in performing this type of work. This chapter identifies analysis approaches, introduces analytical methods, and provides brief comments on validation and verification of results.
This paper/presentation provides a summary of Chapter 2 of the Alternative Load Path Analysis Guidelines, highlighting key topics in the chapter and identifying critical steps in the ALP analysis methodology to inform the practicing structural engineer about this method to reduce the likelihood of disproportionate collapse.