Shear Lag in Stiffened Box Girders

Methods for the analysis of shear lag in wide flanges are reviewed and a treatment is presented which incorporates the effect of the web upon the stress distribution in the stiffened flange of a box girder by replacing the web with an edge stiffener on the flange. Attention is drawn to the effect of severe shear lag on the curvature and displaced shape of a cantilevered box girder. A series of tests on model girders is described and the results are compared with an approximate stiffener-sheet analysis, a more rigorous orthotropic plate analysis, and a plane stress finite element analysis; the latter is used to analyze flanges under more complex conditions. A three-dimensional finite element analysis confirmed the observed curvatures at the section of high shear lag.