Abstract
Current bridge design and rating techniques are based at the component level and thus cannot account for the increase in ultimate capacity that bridges experience because of system-level interactions. Compared with that of a normal bridge, the ultimate capacity of a bridge increases to an even greater extent as bridge supports are skewed because of changes in load paths. Although advances in computer technology have made it possible to conduct accurate system-level analyses, which would allow for more efficient bridge design and rating, the knowledge base surrounding system-level bridge behavior is still too small to make it a highly accurate or intuitive tool. To advance system-level design and rating, two studies were undertaken. First, to evaluate the ultimate capacity of a skewed simple-span steel bridge, a ⅕-scale, slab-on-steel girder bridge was tested to ultimate capacity and then modeled by using finite element analysis. This test provided both insight into the system behavior and validation of an ABAQUS Explicit analysis algorithm and associated modeling techniques. Second, to investigate the effects of skew on the ultimate capacity of simple-span bridges, a parametric study was conducted with finite element analysis. A four-girder, simple-span bridge was modeled with skews varying from 0 to 75 degrees. The results showed that the ultimate capacity of the bridge increased with skew; these results were compared with simple analytical equations to provide insight into the fundamental behavior and load distribution characteristics of skewed bridges.
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