Stability evaluation of cold Formed Steel Pallet Racks under Seismic Condition- A Numerical and Shake Table Study

In this paper, studies on global behaviour of cold formed steel pallet rack systems using a second-order frame analysis formulation are reported. Calibration studies on the developed second-order beam formulation have been carried out. The different global analysis procedures stipulated in the popular code of practice for the design of cold formed steel storage racks (EN 15512 and RMI (2012)) are briefly reviewed. Using the formulation, studies are carried out on tall racks, especially focusing on semi-rigidity of connections and stability. Later, a shake table test is conducted on a two-level pallet rack to investigate the dynamic behaviour of cold formed steel racks subjected to base excitation. A typical earthquake input of El Centro (1940) North-South component is applied, and the behaviour of the cold formed steel racks is studied. The connection flexibility of the upright -- connector tab has been taken from an earlier publication by the author. All joints in the numerical model and experimental work are treated as semi rigid. The paper then describes the effect of connection rigidity on the dynamic performance of the racks. Although the racks could not be subjected to its maximum design load per level, the dynamic characterization that is observed during the test is reported in this paper. It is identified that, a combined dynamic analysis calibrated with numerical solutions is the correct way to assess the seismic performance of cold formed storage racks.

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