Seismic vulnerability assessment of steel storage pallet racks

Steel storage pallet racks are structures composed of cold-formed members designed to store goods. Despite worldwide usage, their dynamic behaviour is still not well known. The goal of this research is to propose a methodology for the seismic vulnerability assessment of steel racks, in terms of fragility curves. The latter are retrieved by means of Multiple-Stripe Analysis, in which the Generalized Conditional Intensity Measure approach is employed for record selection. Two typical rack configurations, unbraced and braced, are analysed, and epistemic uncertainty related to construction details is accounted for by considering different hysteretic connection behaviours and upright moment resistances. Nonlinear dynamic analyses are performed in the down-aisle direction, considering both geometric and material nonlinearities. The obtained results are related to different engineering demand parameters and limit states. The derived fragility functions, if combined with relevant hazard curves, would allow carrying out a seismic risk assessment and mitigation of steel storage racks.