Assessment of constructibility and serviceability for straight and skewed steel I-girder bridges.

摘要

Recent changes to the AASHTO specifications for steel bridge design have incorporated specific provisions for handling lateral flange bending in I-shaped steel girders. The primary reason for the inclusion of this effect is to allow for a unification of design provisions for both straight and curved girders.; In tangent bridges and in bridges with a small degree of skew the influence of lateral flange bending in the fully composite condition in positive bending are negligible. This is predominantly due to restraint offered by the deck and the diaphragm action offered by the deck in lateral load events. However, during construction the load developed due to deck casting as well as lateral loading due to wind must be supported predominantly by the exterior girders with assistance from interior girders through force transfer in the cross-frames and diaphragms.; The goal of this work has been to assess the influence of lateral flange bending in straight and skewed I-girder systems during construction. Refined 3D FEA modeling has been performed on existing and hypothetical tangent and skewed I-girder bridges to assess the influence of system response due to various deck casting sequences, lateral flange bending generated by deck casting and associated finishing equipment, lateral flange bending generated due to wind acting on the non-composite girder, and to evaluate the performance and load levels developed in bracing members during these load events. The FEA procedures employed in these studies are verified against existing physical test data and the results of the studies are compared against AASHTO specification predictions. Additionally, the models used in this study are also analyzed in the fully composite condition to assess the distribution of vehicular live-load and live-load deflections.