Failure Tests of Rectangular Model Steel Box Girders

Model tests were successfully utilized to obtain information on the behavior, modes of failure, and load-carrying capacity of single span rectangular steel box girders. This study, which involved the testing of two slender-web steel model box girders under different combinations of bending, shear, and torsion, provides insight into the post-buckling behavior of such members. The test specimens were designed to simulate box girder bridge members having a concrete or orthotropic steel deck. When subjected to only shear and bending, the specimen exhibited a behavior quite like that of slender-web plate girders under similar loading conditions. The addition of torsion had a significant effect on the behavior of the specimens. For all conditions of loading the specimens displayed definite stress redistribution capabilities and considerable post-buckling strength. Failure modes were characterized by tension field yielding of the webs and out-of-plane deformations of the flanges.