Performance-Based Seismic Design of an Industrial Storage Rack System

Performance-based methodologies are becoming the norm for seismic design and evaluation of building structures, recognizing that designs based on conventional code methodologies may result in inconsistent seismic performance. However, use of these methodologies is not as widespread for non-building structures, which may pose unique structural problems that can also benefit from a performance-based design and evaluation approach. This paper presents performance-based seismic design of a proprietary self-supporting enclosed industrial storage rack system with a box-type steel structure whose exterior dimensions can be varied to accommodate required storage space and geometric constraints. The lateral load resisting system comprises moment resisting frames with bolted connections in one direction and a combination of moment resisting frames and corrugated panels welded to the columns in the orthogonal direction. Three-dimensional nonlinear finite-element models are developed for structural analysis. Structural adequacy is evaluated through (1) AISC-LRFD criteria using a linear response-spectrum analysis and (2) performance-based provisions of FEMA 356 and FEMA 450 for life safety using a nonlinear pushover analysis. The results of the structural evaluation indicate that for more than half of the configurations, the performance-based criteria control the design and rack content weight capacity. Relying solely on elastic analysis and the LRFD design requirements, while satisfying code requirements, leads to structures that violate performance requirements in terms of excessive beam plastic rotations and column axial forces, indicating potentially poor performance during actual seismic events. Furthermore, P-delta effects, in conjunction with large plastic deformations and column compressive loads, significantly reduce the content weight capacity for taller systems with some configurations being disqualified for high seismic regions.