Numerous works have been presented over the years on the ultimate shear behavior and postbuckling strength of plate girder web panels. Research by Basler has been adopted in AASHTO, and the work by Porter et al. has been adopted in British Standard. However, a recent nonlinear finite-element study by Lee and Yoo reveals that considerable discrepancies exist concerning the failure mode between the assumed failure mechanisms and the numerical analysis results; although theories by Basler and Porter et al., yield reasonable ultimate shear strengths for all practical designs. In this study, 10 scaled plate girder models were tested to investigate the shear behavior of web panels up to failure. Test results are compared with values obtained from theoretical models and the finite-element study. Based on this study, the following conclusions are made with regard to the behavior of the plate girder web panels: (1) The boundary condition at the flange-web juncture in practical designs is much closer to the fixity; (2) in all existing failure mechanisms, the through-thickness bending stress effects on the ultimate shear strength are neglected, however, it has been found that very high bending stresses develop at failure; and (3) an anchoring system, such as flanges, is not needed for the development of the postbuckling strength.
