Shake table testing of standard cold-formed steel storage rack

Full‐scale shake table investigations are strongly required to understand the actual performance of storage racks and to improve the rack design guidelines. This paper presents the results of full‐scale shake table tests on New Zealand standard storage rack frames with two‐bay and two‐level to determine the dynamic characteristics of a standard rack structure and to measure the damping of the system. The experimental program was conducted in three phases. First, the identification parameters including the natural frequency and damping of the system were determined through a series of preliminary tests. Then, shake table tests were performed to capture the inelastic response of rack frames under low to medium intensities of El‐Centro ground motion. Finally, the shake‐table tests were repeated with scaling down the time domain and broader ranges of ground motion intensities to consider the performance of taller rack systems. In addition, a comprehensive discussion on the damping of the system is also provided based on the test results. The performance of the rack frame is described through an extensive set of measurements, including rack displacement, pallet sliding, the acceleration of a concrete block and rack frame and the damping of the system in the down‐aisle direction. The results indicate that the standard rack frames are able to endure large inelastic deformations without loss of stability

Experimental and numerical investigation of a method for strengthening cold-formed steel profiles in bending

Perforated cold-formed steel (CFS) beams subjected to different bending scenarios should be able to deal with different buckling modes. There is almost no simple way to address this significant concern. This paper investigates the bending capacity and flexural behavior of a novel-designed system using bolt and nut reinforcing system through both experimental and numerical approaches. For the experiential program, a total of eighteen specimens of three types were manufactured: a non-reinforced section, and two sections reinforced along the upright length at 200 mm and 300 mm pitches. Then, monotonic loading was applied to both the minor and major axes of the specimens. The finite element models were also generated and proved the accuracy of the test results. Using the proposed reinforcing system the flexural capacity of the upright sections was improved around either the major axis or minor axis. The 200 mm reinforcement type provided the best performance of the three types. The proposed reinforcing pattern enhanced flexural behavior and constrained irregular buckling and deformation. Thus, the proposed reinforcements can be a very useful and cost-effective method for strengthening all open CFS sections under flexural loading, considering the trade-off between flexural performance and the cost of using the method

Investigation of a method for strengthening perforated cold-formed steel profiles under compression loads

Cold-formed steel (CFS) storage rack structures are extensively used in various industries to store products in safe and secure warehouses before distribution to the market. Thin-walled open profiles that are typically used in storage rack structures are prone to loss of stability due to different buckling modes such as local, distortional, torsional and flexural, or any interaction between these modes. In this paper, an efficient way of increasing ultimate capacity of upright frames under compression load is proposed using bolts and spacers which are added externally to the section with certain pitches along the height. Hereinto, experimental tests on 81 upright frames with different thicknesses and different heights were conducted, and the effect of employing reinforcement strategies was examined through the failure mode and ultimate load results. Non-linear finite element analyses were also performed to investigate the effect of different reinforcement spacing on the upright performance. The results showed that the reinforcement method could restrain upright flange and consequently increase the distortional strength of the upright profiles. This method can also be effective for any other light gauged steel open section with perforation. It was also observed that the reinforcement approach is much more useful for short length upright frames compared to the taller frames

Stability analysis of steel storage rack structures

Industrial racks are normally framed structures fabricated from cold-formed sections and relative to their self weight (Dead Load) carry very high Pallet Loads (live load) compared with conventional civil engineering structures. Lack of sufficient design rules and specifications provides an urgent need to better understand their performance under seismic loads as well as static load. Due to their slenderness controlling sway deformation is an important factor in the design of industrial racks and hence special attention must be given to factors such as ‘beam to upright connections’ and ‘base plates connections’. This paper focuses on theoretical approaches to perform stability analyses of storage rack structures and considers the effects of incorporating the stiffness of baseplates and bracing elements in the critical buckling load. Also the effect of cyclic moment rotation deterioration on the global stability of the frame is highlighted. A stability limit has been defined for a maximum pallet load to be stored on a particular rack structure