a b s t r a c tIn this paper, the results of an investigation into the post-buckling behaviour of high-strength aluminium alloy stiffened plates subjected to combined axial compression load and different magnitudes of lateral pressure using non-linear finite element approach is presented. Both material and geometric non-linearities have been taken into account. The principal variables studied are the plate thickness, boundary conditions and the stiffener geometries beside the geometrical imperfection, the width of the welding heat-affected zone (HAZ) and welding residual stresses. The influence of these variables on the post-buckling behaviour and ultimate strength of such stiffened plates has been investigated in details.

a b s t r a c tThe present research was undertaken based on the results obtained by the same authors in a sensitivity study on the buckling and ultimate strength of continuous stiffened aluminium plates. Empirical expressions are developed for predicting ultimate compressive strength of welded stiffened aluminium plates used in marine applications under combined in-plane axial compression and different levels of lateral pressure. Existing data of the ultimate compressive strength for stiffened aluminium plates numerically obtained by the authors through the previously performed sensitivity analysis are used for deriving formulations that are expressed as functions of two parameters, namely the plate slenderness ratio and the column (stiffener) slenderness ratio. Regression analysis is used in order to derive the empirical formulations. The formulae implicitly include effects of the weld on initial imperfections, and the heat-affected zone.

Empirical expressions are developed for predicting ultimate compressive strength of welded aluminium stiffened plates used in marine applications under combined transverse in-plane compression and different levels of lateral pressure. A database of the ultimate transverse strengths for aluminium stiffened plates numerically obtained by the authors is used for deriving formulations as functions of two parameters, namely the plate slenderness ratio and the column (stiffener) slenderness ratio. Regression analysis is used in order to derive the empirical formulations. The formulae implicitly include the effects of the weld on the initial imperfections and the heat-affected zone.

A series of elastoplastic large-deflection finite element analyses is performed on stiffened aluminium plates with flat-bar stiffeners under in-plane longitudinal compression loads. Then, the closed-form ultimate compressive strength formula is derived for stiffened aluminium plates by regression analysis. Finally, artificial neural network methodology is applied to predict the ultimate strength of uniaxially compressed stiffened aluminium plates. It is found that artificial neural network models can produce a more accurate prediction of the ultimate strength of the stiffened aluminium plates than can the existing empirical formula.

SummaryReliability-based inspection planning is one of the most popular methods in determining the time of inspection and repairs in various structures. In this way, inspection and repair times are determined mainly by putting a lower limit for the reliability index. The detection and measurement of cracks is one of the possible outputs at the time of inspecting fatigue cracking. One way to use this output is to update the parameters of the fatigue reliability equation. In this study, statistical distribution of the parameters of the problem is updated and fatigue reliability is calculated for inspection planning using the Bayesian updating concept through the Markov Chain Monte Carlo (MCMC) method and the Metropolis-Hasting algorithm. The distribution of crack growth equation material parameters and the initial crack length will be updated with this method. The application of the proposed method has been shown in a structural member of a ship.