Finite element analysis for assessing the flexural performance of CFRP-strengthened composite slabs without overextending reinforcing bars

To address the inherent limitations in design, construction, and quality control associated with the use of overextending reinforcing bars in traditional precast composite slabs, this paper proposes a novel precast composite slab configuration that eliminates such reinforcement protrusions. The joints of the proposed slabs are strengthened using Carbon Fiber Reinforced Polymer (CFRP), and the key construction techniques of this strengthening system are systematically presented. A refined three-dimensional finite element model was developed using the ABAQUS platform to investigate the effects of critical parameters-including the number of CFRP layers, CFRP thickness, and bonding length-on the yield load and deformation behavior of the strengthened composite slabs. The numerical results demonstrate that CFRP effectively restores the stress transfer path in the joint region through a bridging mechanism, thereby improving the load-bearing capacity of the composite slabs. However, when the bonding length exceeds the stress transfer length of the reinforcing bars embedded in concrete, further increases in either the number of CFRP layers or the bonding length yield diminishing returns in terms of load-bearing enhancement. Based on the parametric analysis, a design methodology for CFRP strengthening is proposed, centered on the principles of equal-strength force transmission and effective bond transfer. This approach provides a theoretical foundation for the practical application and wider adoption of CFRP-strengthened composite slabs without overextending reinforcing bars.