Shahriar Shahbazpanahi

A novel numerical model of debonding of FRP-plated concrete beam

Accurate modeling is required to estimate the debonding in a plated fiber-reinforced polymer (FRP) concrete beam. In the present investigation, a numerical method is developed to model a crack in the FRP–concrete interface. An initial notch is located at the mid-span of the concrete beam. A modified crack closure integral method is implemented to model Mode-I fracture in the concrete. In the present research, a special interface element is formulated to simulate and to predict the distribution of interfacial shear stresses by using drilling degrees of freedom in the nodes of interface elements. Cohesive forces in the nodes of interface elements are formulated by finite element methods. A crack propagation criterion is presented to evaluate when the crack grows in FRP–concrete interface. If the principal stress in the node at the tip of an interface element reaches the maximum shear stress along the FRP–concrete interface, debonding happens. The model is robust, accurate, independent of mesh size, and it is able to model the crack growth in the concrete and debonding of the FRP–concrete interface, simultaneously. The model presented in this study showed acceptable similarity to previous research data.

A simple and practical model for FRP-reinforced cracked beam

In this paper, a numerical method is developed to model tensile crack in a three-point bending concrete beam which is reinforced with fibre-reinforced polymer (FRP). In this method, the energy release rate is estimated by considering fracture process zone (FPZ) and more accurate stiffness. To do so, the depth of the beam, the effective crack and the initial notch are considered in the FPZ length. To improve the accuracy of estimation, a spring element is used to model the cohesive zone. The energy dissipation rate is also calculated using virtual crack closure technique in FRP-reinforced concrete beam and then, the crack propagation criterion is presented. The model is easy and accurate, converges fast and is capable to model the crack growth in FRP-reinforced concrete cracked beam. Also, the model presented in this study shows acceptable similarity to the experimental data used.