Interface shear in high strength composite T-beams

Tests of six composite T-beams made with webs of 12,120 psi (83.6 MPa) precast concrete and with flanges of either 728,0 or 11,290 psi (50.2 or 77.8 MPa) cast-in-place concrete showed that the AASHTO and ACI provisions for interface shear of composite beams could be applied conservatively to composite sections constructed with high strength concretes. The 10.5 ft (3.2 m) long T-beams were modeled after similar beams constructed by Loov and Patnaik using normal strength concrete. The flexure tests and interface failure results showed that all equations developed previously could be applied to high strength concrete sections used in bridge construction. The interface shear tests compared well with shear friction push-off tests and demonstrated that the interface shear capacity depends both on the clamping stress provided by the transverse reinforcement and on the concrete strength.