Seismic Performance of Steel Racks Under Varying Pallet Load Distributions

Abstract

Steel pallet racks are widely used in warehouses for storage of various kinds of materials. Due to several peculiarities, their structural characteristics differ from usual steel structures. Their typical typology consists of semi-rigid moment resisting frames in down-aisle direction and braced upright frames in cross-aisle direction. Many parameters influence the structural response of steel pallet racks, why tests are required to characterize stiffness and nonlinear connection behavior. One peculiarity is the very large ratio of pallet unit weight to self-weight and thus the variety of possible loading levels. In this paper, the influence of the loading level and the pallet unit distribution on the seismic performance of a realistic steel pallet rack is investigated by modal, nonlinear static, and nonlinear dynamic analyses in OpenSees. The fully loaded structure showed to be in general the most severe condition. However, for single earthquakes, a less loaded rack and a non-uniform distribution of pallet units may result in a more critical behavior. Throughout the paper, a self-developed, comprehensive MATLAB environment is presented, which was used for pre- and post-processing tasks.