Flexural behavior of steel concrete composite beams with rebar shear connectors

Abstract

A steel concrete composite beam is defined as a hot-rolled or a built up structural steel shape that is structurally connected to a reinforced concrete slab. Shear connectors are provided at the interface between steel beam and concrete slab to resist the horizontal shear between the two components. Among the different types of shear connectors used in composite beams L-shape rebar connector are easy to install and cost effective as compared to other connectors. However, no research is found in the published literature on the flexural behavior of composite beams with rebar connectors. An attempt has been made in this study to conduct experimental investigations on the flexural behavior of steel concrete composite beams with rebar type connectors through two point load test. The test specimens were designed to study the effect of bar diameter and spacing of rebar connectors. One test beam was constructed without connectors to be used as reference beam. The behaviour of the composite beams were compared with that of the noncomposite beam (beam without shear connector). Finally the experimental moment capacities were compared with the theoretically predicted capacities.

The experimental results were studied with respect to the moment vesus midspan deflection curve, ultimate moment capacity, corresponding deflection and interfacial slip between steel and concrete. The failure behaviour of the test specimens were also examined. The failure of the composite beams were initiated by flexural shear crack of concrete slab followed by local buckling of the steel flange. Separation between steel flange and concrete slab was also observed at failure. The moment deflection response of the composite beams was observed to be significantly affected by the composite action. The maximum enhancement in the ultimate moment capacity of the composite beam specimens was found to be 44% with respect to the noncomposite beam. The maximum vertical deflection and horizontal slip at the steel concrete interface was reduced significantly due the presence of shear connectors at the steel concrete interface. Moreover, the experimentally obtained moment capacities were found to be higher than the predicted capacities for most of the specimens except the specimen with highest composite action.