BUCKLING ANALYSIS OF PLATED STRUCTURES USING SYSTEM RELIABILITY CONCEPTS

A method for predicting the structural reliability of stiffened plates is presented, for situations where buckling response is important. The approach adopted for predicting buckling strength consists of a plate panel model, based on the idealization of the load end-shortening relationship by piece-wise linear segments, which is then employed within an inelastic beam-column analysis to model stiffened plates. Thus, the proposed model can trace the complete load end-shortening response of a stiffened plate under axial and lateral loading. Implemented as a safety margin within a FORM reliability analysis, it is a suitable tool for quantifying the effect of variations in design and manufacturing parameters influencing stiffened plate reliability. The plate model can also be used independently in order to examine the reliability of panels under axial compression and lateral pressure. The use of these models is demonstrated through probabilistic modelling and reliability assessment of plate panels and stiffened plates under in-plane compression. Special emphasis is devoted to examine the effect of the amplitude and mode of the initial geometrical imperfections and of the level of the welding residual stresses. Due to the possibility of attaining maximum plate panel resistance at various points on the load end-shortening path, a simple parallel system representation is adopted in the reliability analysis. On the other hand, in stiffened plate analysis, the mode of failure depends on the characteristics of the imperfection profile along the length of the stiffened plate. A set of initial imperfection profiles is examined and each profile is considered to constitute an element within a virtual series system.