Simplified Method for Calculating the Lateral Stiffness of Drive-In Storage Racks

Abstract

Drive-in storage racks, made of cold-formed steel, are the main racking system used in industry for storing goods. The storage space utilization of drive-in racks is high at the price of the weak downaisle stability. This paper presents a general analysis of the lateral stiffness of drive-in racks in the downaisle direction. A total of 24 static tests of drive-in rack systems have been conducted under single-point horizontal force. The effects of some constructional details, such as bracing configuration, cargo pallets, and the number of bays, are considered. The experimental results indicate that either top plan bracing or back-spine bracing can change the load transfer through rack structures and increase the lateral stiffness of racks. By acting as the horizontal bracings of adjacent columns and reinforcing the rotational stiffness of column bases, the stored pallets are also the beneficial factor for improving the lateral stiffness of racks. According to the special structural characteristic of tested racks, the simplified models and calculation formulas are proposed for the lateral stiffness of tested racks with bracings and without goods. To consider the influence of local deformations in bracing member connectors, sectional area–reduction factors of bracing members are introduced in the simplified calculation method. The lateral stiffness of a complete rack system can be used to determine the lateral horizontal restraint at the top of each rack column, which has large effect on the load-carrying capacity of columns in drive-in racks. In the last part of the paper, three drive-in rack examples with typical section properties and overall dimensions are presented to illustrate the computational procedure of horizontal deflection of drive-in racks.