FLEXURAL BEHAVIOR OF CONCRETE-STEEL HYBRID BRIDGE GIRDERS

The experimental results from a full-scale test are compared with anal ytical predictions in order to investigate the behaviour of a hybrid b ridge girder with a reinforced concrete web and steel flanges. A linea r analysis indicates that restrained shrinkage had a significant influ ence on initial cracking of the concrete web. The longitudinal strains , predicted by a nonlinear flexural analysis accounting for shrinkage and construction stages, compare well with the strains measured during the test. The average widths of the flexural cracks at the service lo ad level are predicted using an empirical average crack spacing approa ch. The modified compression field theory is used to predict the diago nal cracking of the web due to combined shear and bending moment. A ri gorous nonlinear analysis indicates that the effects of creep, load-cy cles, and shear deformation must be accounted for in predicting the di splacement of the girder. Finally, sectional strength calculations ind icate that the distributed longitudinal reinforcement in the web contr ibutes significantly to the flexural capacity of the hybrid girder.