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 due to system level interactions. The ultimate capacity ofa bridge increases to an even greater extent as the bridge supports are skewed. While 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. In order to advance system level design and rating, the authors have undertaken two studies. First, to evaluate the ultimate capacity of a skewed simple-span steel bridge, a 1/5th-scale slab-on-steel girder bridge was tested to ultimate capacity and then modeled using finite element analysis. This provided both insight into the system behavior as well as validation of an 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 using finite element analysis. A four girder simple-span bridge was modeled with skews varying fromzero to 75 degrees. The results showed that the ultimate capacity of the bridge increased with skew and these results were compared with simple analytical equations to provide insight into the fundamental behavior and load distribution characteristics of skewed bridges.
Abstract