Pull-out test and discrete spring model of fibre-reinforced polymer perfobond rib shear connector

In this study, a series of pull-out tests on fibre-reinforced polymer (FRP) perfobond rib shear connectors were conducted to investigate their shear behavior. The test specimens were designed to examine only the effects of the resistance by rib holes. The test variables were the size and number of rib holes. In the tests, the resistance by concrete dowel action was practically linearly proportional to the area of the rib hole. However, the resistance appeared to be nonlinearly proportional to the number of rib holes with a slight loss for a larger number of the rib holes, due to the sequential failure of the rib holes. The constitutive equation of the discrete spring model representing the concrete dowel including post-failure frictional effects, adopting the diameter of the rib hole as parameter, was derived through regression analysis of the load - relative displacement curve obtained for specimens with a single rib hole. The proposed discrete spring model resulted in good correlation with the experimental results for specimens with a larger number of rib holes. It is expected that the derived constitutive equation would be useful for the analysis and design of structures using FRP perfobond rib shear connectors.