DETERMINATION OF EFFECTIVE BREADTH AND EFFECTIVE WIDTH OF STIFFENED PLATES BY FINITE STRIP ANALYSES

A finite strip (FS) method is presented for the numerical investigatio n of two design parameters - effective breadth and effective width - o f stiffened plates. For the effective breadth, stiffened plates under bending are studied. Due to the transverse bending loads there is shea r transmission through the plate from the stiffener which leads to a n on-uniform longitudinal stress distribution across the plate width. Th is phenomenon, termed as shear lag, can be represented by the 'effecti ve breadth concept', and has been extensively studied by analytical me thods, A linear FS method is presented which utilizes the advantages o f decoupling of Fourier terms on the one hand and, on the other hand, allows the treatment of both webs and flanges using a plate model. A d efinitely different situation exists for estimating the effectiveness of the plate breadth (or width) of plates in the postbuckling range. T he 'concept of effect width' is based on the fact that plates with sup ported longitudinal edges and/or stiffeners can accept additional load after buckling under longitudinal compression, and enables the design er to evaluate the postbuckling strength of plate structures simply by using the design parameter 'effective width'. Several formulae (most of them empirically derived) exist for an approximative calculation of the load dependent value of the effective width. A nonlinear FS metho d is developed and applied to the investigation of the postcritical st rength of locally buckled structures. An incremental successive iterat ive procedure is introduced for an effective numerical analysis. Copyr ight (C) 1996 Elsevier Science Ltd.