DETERMINATION OF BASE PLATE STIFFNESS OF STEEL STORAGE RACKS

Abstract

In recent trends the development of structural steel using cold formed steel section plays a vital role in main frame construction of portal frames. These frames find its use in the construction of economic industrial, agricultural and residential buildings due to its lightweight and robustness. With the major claims in comparison with hot rolled steel profiles, cold formed steel possesses low cost, highly versatile with standard design procedures. Among various structural designs, industrial storage racks are the most prominent structures constructed using cold formed steel. It has been widely incorporated with the rational space utilization in warehouses and factories for goods storage. These rack systems have been classified as static and dynamic types. The adjustable pallet rack was found to be the commonly used static system. It consists of transversal beams and column upright which is grounded with base plate connections. This system provides the stability in down aisle direction. The beams (stringers) have boxed cross-sections while columns (uprights) are open thin walled perforated to accept the tabs of beam end- connectors, which join beams and columns together without bolts or welds. This paper addresses the problem of determining the stiffness and strength of steel storage rack base plate assemblies. Base plate assemblies are usually bolted to an upright and to a concrete floor, and they are used to provide resistance against the flexural buckling of the upright and/or the overall down-aisle buckling of the frame. The semi-rigid stiffness is usually determined by means of a test of two pre-loaded uprights connected to a concrete block in a dual-actuator set-up. Guidance for conducting the test is provided in the European Standard EN 15512. However, several aspects of the test need clarification, notably the test set-up and the transducer arrangement for measuring the rotations of the base plate. Keywords: storage rack, base plate assembly, initial rotational stiffness.