Interaction between Cross Frames and Girders

Abstract

This paper presents a three‐dimensional finite element algorithm for computing internal forces in intermediate and end cross frames of multibeam composite steel bridges. The developed algorithm was applied to four medium‐span [137 ft (41.75 m)] simply supported multigirder tangent four‐lane bridges, with X‐type intermediate cross frames and end cross frames of the Warren truss with verticals type. One was a right bridge and the others had 20°, 40°, and 60° skew angles. It was found that: (1) Most members of the intermediate cross frames may develop compressive and tensile forces; (2) maximum compressive forces occur in the cross‐frame diagonals attached to the ends of exterior stringers, close to the obtuse angles of the bridge; (3) maximum tensile forces occur in the cross‐frame chords, at midspan; (4) the effect of skew may be neglected for skew angles of 20° or less; (5) the higher the skew angle, the higher the maximum forces induced in the cross‐frame members; (6) the larger the cross‐frame members' ...