The Analysis of Irregular Shaped Diaphragms

Several decades ago, the residential and commercial buildings being designed tended to be straightforward, redundant structures with simply laid out lateral resisting systems. These structures had a minimum number of horizontal and vertical offsets. In contrast, the structural configurations of many modern buildings require complex lateral load paths that incorporate diaphragms at different elevations, multiple re-entrant corners, multiple irregularities and fewer vertical lateral force-resisting elements. It is important to address these design issues and irregularities to ensure complete load paths throughout the structure; however, this doesn’t have to be a daunting task. 

Knowledge regarding the analysis of complex diaphragm layouts varies greatly within engineering and code enforcement communities. The purpose of this paper is to bridge that information gap by providing an overview of a method, based on simple statics, which can be used to analyze complex diaphragm structures, while guiding readers to more detailed information through the references.