Influence of bending and dowel action on the interface bond in RC beams strengthened with FRP sheets: An experimental investigation

This paper presented the test results on a series of RC beams externally bonded with FRP sheets under coupled bending and dowel actions. The main focus was to investigate how the dowel force acting on the FRP sheets influences the shear transfer capacity of the bond between the FRP and concrete. A loading system was developed to simultaneously introduce shear and normal stresses into the FRP-concrete interfaces. Interfacial failure criteria under different loading conditions were discussed. It was found that the dowel force on the FRP sheets affected greatly the initiation of local interface peeling which led to a decrease of the beam's stiffness. However, the ultimate flexural capacity was not significantly influenced by the existence of the dowel action if a sufficient anchorage length was available. The paper also provided a benchmark database that can be used for calibrating the mix-mode bond constitutive laws for FRP-concrete interfaces.