A practice-oriented methodology for seismic loss assessment of steel storage pallet racks

Steel storage pallet racks, globally used across various industries for storage and logistic purposes, are essential components of modern infrastructure. Consequently, given their crucial role, they must remain operational in the aftermath of extreme events, such as earthquakes. The damage sustained by steel racks in previous earthquakes calls for loss assessment methodologies, which are currently lacking, to prevent significant losses and to facilitate the planning of retrofit strategies and future investments for risk mitigation. This study contributes to filling such a gap by comprehensively examining the seismic vulnerability of steel storage pallet racks and the lack of available damage models for rack components, proposing a practice-oriented methodology for their loss assessment. The methodology is applied to three steel storage pallet rack archetypes, demonstrating its ability to estimate risk metrics (e.g., total losses and expected annual losses). To do so, multiple stripe analyses were conducted, assuming two different locations in Italy with medium and high seismic hazard levels. Then, collapse fragility curves were derived, together with the risk metrics, showing the impact of the hazard levels on the median intensity of collapse and the individual contribution of structural elements and contents to the total annual losses. The proposed methodology empowers industrial stakeholders to better understand and quantify seismic risk associated with rack systems.