Analysis of steel-concrete composite frames with bond-slip

Recent developments in modeling the slip in steel-concrete composite beams have led to an accurate and numerically stable force-based frame element. The element assumes force fields rather than displacement fields along the element. After a brief review of the element formulation, the paper discusses a new phenomenological law for the shear connection between steel girder and concrete slab that considers stiffness and strength degradation. Correlation studies with available push-pull tests on shear connectors are used to validate the proposed model. The steel-concrete composite frame element is then applied to (1) the study of a composite structural subassemblage. for which experimental data are available; and (2) the analysis of a three-story, four-bay steel building with a composite deck. In the first case, good agreement is obtained with the experimental results for both full and partial connection conditions. In the second, the study shows the increase in stiffness and strength due to the composite action. The accuracy of the force-based element leads to the use of one or two elements for a single structural member, thus allowing entire frame analyses to be performed economically.