Nonlinear FEA of mechanical anchorages on CFRP-to-concrete bonded joint

Abstract

The debonding of carbon fibre-reinforced polymer (CFRP) strips from the surface of concrete is one of the main premature failure modes for concrete beams that are externally strengthened with CFRP strips. Many anchorage systems are developed to prevent or delay the debonding process in these beams in order to improve the ultimate load capacities. In this study, nonlinear finite-element analyses (FEAs) are performed by employing ABAQUS software to describe the load-deflection behaviour and ultimate loading capacities of concrete beams whose flexure has been strengthened using externally bonded CFRP strips with mechanical anchorages. First, the nonlinear finite-element model results are validated using the results of an experimental study previously carried out by the authors. In the experimental study, the variables investigated are the CFRP strip width and the number and the arrangement of the mechanical anchorages. A good agreement is demonstrated between the numerical and the experimental results. Then, a parametric study is conducted to investigate the effects of the mechanical anchorages on the ultimate load capacities of concrete beams. Consequently, the variable, the CFRP bonding length, is included into the finite-element models that are corrected with the experimental results, and equations involving many variables concerned with the ultimate loading capacities are suggested. Finally, an ultimate load capacity multiplier is proposed enabling the calculation of the ultimate load capacities of beams mechanically anchored with CFRP strips, with regard to the CFRP strip width, the bonding length, the number of mechanical anchorages and the arrangement of the variables.