Seismic Fragility Assessment of Industrial Pallet Racks in Italy

Steel pallet racks are critical non-structural systems widely used in warehouses and production facilities. Despite their apparent simplicity, their seismic vulnerability can strongly influence the overall risk profile of industrial assets –especially in seismic-prone regions. Past earthquake events have shown that rack collapses not only endanger worker safety but can also trigger major economic losses due to damage to stored goods, prolonged production downtime, and supply chain disruptions. Yet, their seismic behaviour remains understudied, and quantitative tools for assessing their seismic fragility are still limited. This study addresses this gap by proposing a robust and scalable methodology for seismic fragility assessment of industrial pallet racks. A stock of unbraced rack configurations, representative of the Italian context, was analysed through advanced 3D nonlinear finite element modelling and cloud-based time-history analysis. Fragility curves were derived with respect to multiple Engineering Demand Parameters (EDPs) and seismic Intensity Measures (IMs), considering both rigid and soft soil conditions. The results reveal the considerable seismic vulnerability of the investigated systems and identify global upright strain as the most reliable performance indicator for collapse. Specifically, rack failure is governed by the combined effects of axial–flexural deformation in the uprights, the nonlinear behaviour of beam-to-column joints, and the directionality of the seismic input. These findings, along with the proposed fragility models, can support the development of targeted seismic risk mitigation strategies, as well as more informed and effective industrial safety planning.