Measured behavior of a curved composite I-girder bridge

Current techniques for the rating of horizontally curved composite steel girder bridges often use approximate methods of linear elastic analysis based on the assessment of individual straight girders with altered properties to account for member curvature. This paper summarizes measured versus computed results from a field test with heavy live load conducted on a multi-span, horizontally curved composite steel I-girder bridge in Duluth, Minnesota. Eight 320 kN (72,000 lb) trucks were placed on the bridge in 43 static and 13 dynamic loading configurations, and the results were compared to those obtained from linear elastic grillage analyses. Stresses up to 75% of the girder yield stress were obtained in the bridge, whose design was controlled by strength, thus representing some of the largest stresses ever achieved in an instrumented curved steel girder bridge, and behavior is described in the girders, diaphragms, lateral wind bracing, deck, bearings, and fatigue details. Grillage analyses are developed and used to corroborate the results and assess the accuracy of these procedures for load rating of bridges.