Evaluation of Seismic Design Parameters for Modular Metal Buildings in High Seismic Zones

The objective of this paper is to evaluate the seismic design parameters for modular metal building systems in high seismic zones in the United States using the FEMA P695 methodology. Modular metal buildings, commonly used for large open spaces such as warehouses and data centers, combine traditional built-up tapered steel frames with intermediate gravity-only columns. A suite of archetype buildings with varying spans, heights, and numbers of modules was developed in collaboration with industry and analyzed using nonlinear static and dynamic procedures. High-fidelity shell finite element models, validated against component and shake table tests, capture key failure modes including local and global buckling. Results from pushover and quasi-static cyclic analyses were used to calibrate nonlinear single-degree-of-freedom models for subsequent incremental dynamic analyses against the FEMA P695 earthquake suite. The study demonstrates that modular metal buildings designed with a response modification factor  = 3.5 meet the FEMA P695 collapse performance criteria, provided that lateral bracing systems are designed to meet both strength and stiffness requirements of AISC 360. Buildings using traditional strength-only bracing exhibited limited ductility due to premature column buckling, whereas AISC-compliant bracing achieved stable post-peak response and improved collapse margins. A collapse drift limit of 6% is proposed based on system flexibility and observed behavior. The findings confirm the adequacy and applicability of current ASCE 7 Ordinary Moment Frame provisions for modular metal building systems, with important implications for design practice in high-seismic regions.