Ultimate flexural strengths of plate girders subjected to web local buckling

The ultimate flexural strengths of bisymmetric and monosymmetric I-girders subjected to local bend-buckling in webs have been investigated by nonlinear finite element analysis incorporating post-buckling behaviors. The plate girders fabricated with high performance steel (HPS) and conventional steel were modeled three-dimensionally with thin shell elements and ultimate strength analyses were conducted utilizing versatile nonlinear techniques provided by a commercial finite element analysis (FEA) package program, ABAQUS. The constitutive relationship for both HPS and conventional steel was assumed to be elasto-plastic strain-hardening, and the initial imperfections were considered in the web panels and the residual stresses were imposed on the hypothetical built-up sections. The ultimate flexural strengths of girders with various slenderness of web were evaluated from the nonlinear FEA and compared with values predicted by the specifications in AASHTO LRFD and Eurocode 3. It has been found that the current flexural strength formulas for conventional steel girders from AASHTO LRFD and Eurocode 3 can be extended to application for HPS girders without modification.