Numerical and experimental study on effect of boundary conditions during testing of stiffened plates subjected to compressive loads

•Effect of boundary conditions on stiffened plates behaviour is analysed experimentally.•Behaviour of the supporting structure is investigated.•Ultimate strength and post-collapse shapes of tested specimens are analysed.•Experimental results are compared with finite element analyses.•The analysis has shown that nearly clamped boundary conditions were achieved.•This complies with the real ship structural behaviour of similar components. This study analyses the effect of boundary conditions during testing on the structural behaviour stiffened plates with different thicknesses subjected to compressive loads. The goal of the compressive tests is to analyse the ultimate strength of a stiffened plate. During the test, relevant physical quantities are measured and investigated. The supporting structure's behaviour is investigated by analysing the force-displacements relationship and post-collapse shapes of tested specimens. The experimental results are compared with the ones made by FE analyses. The FE model is explored in two variants, considering clamped and simply supported boundary conditions. A detailed comparison of the lateral deflections of plates near the supports is also performed. The analysis has shown that nearly clamped boundary conditions were achieved during the test, leading to an almost complete restriction of plate rotations during the experimental testing, which complies with the real ship structural behaviour of similar components when deep girders transversally support them.