Investigation of Steel-Truss Reinforced Concrete Beams Under Longitudinal Shear Loading

Steel-truss reinforced concrete beams offer many advantages relative to conventionally reinforced concrete beams. A critical performance parameter of such beams is the load-sharing mechanism between the embedded pre-fabricated truss and the surrounding concrete in the beam. This load sharing, which occurs through shear transfer between the truss and the concrete, has been experimentally investigated following the procedure given in BS EN 1994-1-1:2004. Scaled truss-reinforced concrete beams were subjected to push-off tests under displacement-controlled loading and crack formation, shear transfer capacity and failure modes were noted. For the selected sinusoidal truss geometry, results indicate that shear failure was characterized either by concrete crushing at the base of the truss or by the local plastic deformation of the truss web bars in proximity to the base of the truss. Since the observed load–slip behavior was similar to that of composite sections reinforced with headed shear studs, the predictive strength equation provided in BS EN 1994-1-1 has been examined in estimating the longitudinal shear capacity of steel truss–reinforced concrete beams. The findings of this study should promote the rational design of steel-truss reinforced concrete beams.