Behavior of RC members strengthened in shear with EB FRP: Assessment of models and FE simulation approaches

Numerical analyses are performed with the ADINA finite element (FE) package to predict the behavior of beams shear-strengthened using externally bonded (EB) fiber reinforced polymers (FRPs). Nonlinear material behavior of the plain concrete, steel reinforcing bars, FRP composites and FRP/concrete interface are simulated with appropriate constitutive models. In the FE analysis, the use of truss elements versus shell elements to simulate the behavior of the FRP composites is evaluated. The influence of three types of interface element to represent the FRP/concrete interfacial behavior is examined. These elements are spring elements, discrete truss elements and continuous truss elements. The appropriate interface element is selected on the basis of the best fit of numerical predictions obtained for a predetermined set of experimental data. In order to investigate the influence of including horizontal interface elements, the interfacial response is provided parallel and perpendicular to the fiber orientation to examine the horizontal component of the principal diagonal-tension stresses. It is shown that the approach identified to represent the FRPs and the FRP/concrete interfacial behavior can significantly influence the numerical predictions of FRP shear-strengthened beams.