Simplified approaches to design medium-rise unbraced steel storage pallet racks. Part 2: fundamental period estimates

This paper concludes a two-part paper, which addresses the reliability of simplified approaches for rack design. The first part presents a parametric study on medium-rise, unbraced racks differing for components, geometry, and flexural stiffness degree of beam-tocolumn joints and base-plate connections. The evaluation of the elastic critical load multiplier, which is required to select the analysis method and check member instability, is considered through a simplified approach that is adequately calibrated for the more traditional steel structures. This second part focuses on seismic design, which is governed by the value of the fundamental period of vibrations (T1). Simplified approaches from the literature on typical steel frames and recommendations to predict period T1 are applied to two beam formulations differing in the absence or presence of warping. Research outcomes are discussed, considering the limits of the simplified approaches, and improvements to increase the accuracy of fundamental period prediction are proposed. For reproduction purposes, this paper details the data used in the application of the considered simplified approaches and the previously discussed approaches.