Analytical Bond-Slip Model for Fiber-Reinforced Cementitious Matrix-Concrete Joints Based on Strain Measurements

An accurate bond-slip model is of fundamental importance to analyze the response of fiber-reinforced cementitious matrix (FRCM) composite-strengthened structures. This study proposes a method to determine the bond-slip model of FRCM-concrete joints based on longitudinal fiber strains. First, discrete strain profiles measured with strain gauges were fitted by a continuous function epsilon(y), where y is the coordinate along the bonded length. Then the slip s(y) and shear stress tau (y) along the composite bonded length were obtained by integration and derivation of epsilon(y), respectively. The debonding load and peak load from single-lap direct shear specimens were predicted by the fitted function epsilon(y) and showed good agreement with test results. From the plot of the tau(s) relationship obtained from epsilon(y), an alternative, closed-form, continuous bond-slip relationship was obtained based on the maximum shear stress tau m and the corresponding slip sm. The fracture energy was compared for both relationships and was in reasonable agreement with values reported in previous studies.