Structural ductility in hybrid high performance steel beams

The present study employs experimentally verified nonlinear finite element modeling techniques for the study of hybrid high performance steel I-shaped beams. An evaluation as to the appropriateness of using the current American building and bridge specification (as reported by AASHTO in 1998 and AISC in 1999) provisions for cross-sectional compactness and adequate bracing is carried out within the context of applications involving A709 Gr. HPS483W high performance steel. It is observed from the current research that hybrid high performance steel (HPS) beams proportioned and braced according to current AISC and AASHTO flange compactness, web compactness, and bracing provisions, will exhibit less than half of the required flexural ductility needed to accommodate inelastic force redistribution. As a result of this observation, new flange compactness criteria, as well as new bracing criteria, are proposed in the present paper for use in the design of A709 Gr. HPS483W hybrid beams employing compact webs made from lower strength steels.