Mechanics and Mechanical Engineering Vol. 17, No. 2 (2013) 207–220 c ⃝ Lodz University of Technology Sensitivity to Imperfections of Perforated Pallet Rack Sections Viorel Ungureanu Dan Dubina Department of Steel Structures and Structural Mechanics Civil Engineering Faculty ”Politehnica” University of Timisoara Ioan Curea 1, 300224 Timisoara, Romania Laboratory of Steel Structures Romanian Academy – Timisoara Branch Mihai Viteazu 24, 300223 Timisoara, Romania Received (11 March 2013) Revised (16 April 2013) Accepted (20 May 2013) The paper analyses the influence of imperfections on the behaviour of perforated pallet rack members in compression using non-linear FE simulations. The effect of imperfec- tions, perforations and buckling modes, reduces significantly the capacity of perforated members in compression, especially in the coupling range due to interaction. A sensitiv- ity analysis done using calibrated and validated numerical models can be done in order to determine the most detrimental combinations of imperfections to be considered for numerical simulations. The ECBL approach can be successfully applied to perform a sensitivity analysis via numerical simulations, using a limited number of experimental tests. Keywords : Cold formed section, sensitivity analysis, ECBL method. 1. Introduction All structures are in reality imperfect. The imperfections refer to cross–section and member geometry, to residual stresses and to yield strength distribution across the section, to supporting conditions of the members and to load introduction. Excepting the last two types of imperfections, which are of mechanical type, a lot of work has been done to analyse, classify and codify the material and geometrical imperfections [1–6]. It was observed the different nature of imperfections, associated with the slen- derness of component walls, leads to different instability behaviour of cold–formed sections compared to hot–rolled ones [1]. As a consequence, specific buckling curves should be provided for cold–formed steel sections instead of using European buckling curves obtained for hot–rolled ones.