Reliability-based design of corrugated web steel girders in shear as per AASHTO LRFD

Abstract

Despite their successful use in many bridges across several countries around the world, corrugated web steel girders (CWSGs) haven't been yet recognized formally by mainstream design codes and standards. CWSGs can be an economical alternative to conventional welded plate girders; they can achieve higher shear strengths with lesser material usage. Corrugated webs have been demonstrated to carry about half of their ultimate shear strength after buckling, which is an important reserve strength to overcome sudden collapses of bridge structures. The current design practice combines the latest research in the field with engineering judgment with no regard for reliability-based design. In light of the new developments in the field of bridge design and reliability analysis techniques, this paper revisits first the reliability of welded plate girders in shear and verifies their target reliability index and the corresponding resistance factor as per AASHTO LRFD. Then, and in an attempt to prepare the inclusion of CWSGs shear design in AASHTO LRFD, a probabilistic-based calibration procedure is applied to calibrate the resistance factor for bridges having a range of span lengths and girder spacings, with consideration of different average daily truck traffic. A series of sensitivity analyses were carried out in order to quantify the relative contribution of each design parameter to the overall reliability of CWSGs in shear. The findings of this study suggest that, for CWSGs in shear, a resistance factor of 0.95 is appropriate to ensure a reliability level that is consistently close to the target. The sensitivity analysis showed that the web thickness, web depth, and the yield strength of the web's steel material are the most influential parameters on the reliability index of CWSGs.