End Forces on Crossframes in Horizontally Curved Steel I-Girder Bridges

Crossframes in horizontally curved steel I-girder bridges are primary members. They must be designed for strength and fatigue. Curved girder analysis computer programs typically compute crossframe member forces only due to curvature effect; they do not calculate the crossframe forces due to wind and centrifugal forces. These forces must be calculated separately and combined with the curvature-effect forces using appropriate group combination load factors. If the crossframe forces from computer programs are suspicious, engineers can use hand procedures such as V-load method to verify these results. Also per current AASHTO Guide Specifications for Horizontally Curved Steel Girder Highway Bridges, when the girders are allowed to be analyzed neglecting curvature, the crossframe forces may be determined using the V-load method or other rational means. Using V-load method to find crossframe forces can be time consuming and mistakes are easily made. In this paper, a general solution to determine the end shears and end moments on crossframes in horizontally curved steel multi I-girder bridges is developed by V-load method. In addition, the end shears and end moments on crossframes are tabulated for 2-girder through 8-girder system. A design example for a 5-girder system is selected for demonstration.