This paper investigates the sensitivity of the buckling and post-buckling behaviour of imperfect steel plates used in marine structures when subject to variations in their initial conditions. The analyses were carried out using the non-linear finite element program ABAQUS. The results obtained for several plate models show that the most relevant parameters affecting the buckling and post-buckling of uniaxially loaded plates are unloaded edges boundary conditions and initial out-of-plane imperfection amplitude. A regression analysis was performed for all ABAQUS data points in order to obtain a non-linear model for the ultimate compressive strength of plates. This resulted in three different non-linear regression curves for ultimate strength, reflecting the mean, lower and upper bound models. A comparison between the previously mentioned analytical models and the derived average model is presented showing the existence of discrepancies between them.
In many marine structures the component steel plates experience significant compressive loading under normal operational conditions. As a consequence, the designer needs to consider the main parameters which influence plate strength: aspect ratio, initial imperfections, boundary conditions and material properties. Until recently, the available formulae for the design of unstiffened plates under compressive loading were based on experimental data. With the development of finite element analysis towards non-linear algorithms and the increase in computing capacity it has now become possible to compliment the existing experimental data set with numerical results. Verified numerical models offer a practical method for exploring parametric sensitivity. This paper presents the results of a parametric investigation into the stractural collapse of unstiffened steel plates when subject to variations of botmdary conditions, and initial out-of-plane imperfection. This analysis was performed using ABAQUS 5.7, a non-linear finite element code developed by Hibbitt, Karlsson and Sorenson (1998).
