Evaluation of Seismic Design Parameters for Metal Buildings with Heavy Wall and Heavy Roof in High Seismic Zones

Abstract

The objective of this paper is to explore the seismic performance of metal building systems when they are designed as steel ordinary moment frames (OMFs), but have wall and roof dead loads that exceed prescriptive limits in the United States loads standard (ASCE 7). A set of archetype frames — spanning both clear span and modular metal building system geometries — was developed in collaboration with industry and subjected to a FEMA P-695-based seismic assessment. At the core of the assessment is an advanced shell finite element model of the metal building systems, exercised through a nonlinear hysteretic protocol to accurately capture the response of the system. The shell finite element models inform the calibration of nonlinear single-degree-of-freedom models used in incremental dynamic analyses under the FEMA P-695 ground motion suite. The results show that heavier roof and wall loads can reduce system ductility and collapse margins in certain configurations. However, all archetypes that satisfy a set of simple frame member proportioning criteria, achieve acceptable performance under the evaluated seismic demands. These findings support the extension of OMF-based designs to heavier wall and roof loads if the additional proportioning requirements are included.