Shear lag in orthotropic beam flanges and plates with stiffeners

An FEM parametric study of the stress distribution in orthotropic beam flanges was performed. Several beam boundary conditions and cross sections were considered explicitly. The practical variations of cross-sectional dimensions were extended in order to cover the case of thin cover plates with stiffeners. In the FE analyses a two-dimensional plane stress model was used. An empirical formula was established for the shear lag coefficient lambda which is used for computing the effective flange width B-c = lambda B for stress calculations. Longitudinal flange stiffeners can be accounted for by modifying the E/G ratio. The formula is accurate and gives good results even for small T-f/T-w and high E/G ratios, as is the case with fiber reinforced laminated composite plates with stiffeners. Several existing analytical solutions, discussed in the paper, an not reliable for this case.