Recommendations of bridge distribution factors for military vehicles on steel beam bridges

Analyses were carried out to develop live load distribution factors for the seven most common US Army military vehicles on ninety steel multi-beam bridges. The bridges were analyzed by the finite element method (FEM) to obtain distribution factors. The study included load testing of a steel bridge using a dump truck. The experimental results were used to assess the reliability of the FEM. Results showed that the FEM is effective to calculate the bridge behavior when it is subjected to moving loads. From the results, 56 regression formulas were developed, eight for each of the seven vehicles considered. The live-load distribution factors calculated with the proposed formulas compared well with FEM results. These formulas resulted in less conservative distribution factors than those prescribed by AASHTO and previous studies. The new formulas will result in more accurate, less conservative and more efficient bridge load ratings for bridges on US Army garrisons.