Critical shear crack theory in evaluating the behavior of reinforced concrete flat slabs strengthened with fiber-reinforced polymer composites

Articles in Press

Authors

1 School of Civil Engineering, College of Engineering, University of Tehran

2 Department of Civil Engineering, Isfahan University of Technology (IUT)

10.22034/ceej.2026.66620.2426

Abstract

Strengthening reinforced concrete (RC) flat slabs with fiber-reinforced polymer (FRP) composites is an effective method to enhance their load-bearing capacity. FRP-strengthened slabs may fail in flexural, shear, or combined modes. Flexural failure may occur due to FRP debonding, FRP rupture, or crushing of the concrete in compression, while shear failure appears as punching shear around the column. Accurate assessment of the overall behavior and failure mode before and after strengthening is essential for proper design of the required amount of FRP. This study evaluates the load–rotation behavior of three flat slab specimens using the Critical Shear Crack Theory (CSCT). One specimen serves as the control, while the other two are strengthened with FRP strips using externally bonded reinforcement (EBR) and externally bonded reinforcement on grooves (EBROG) methods. The results indicate that if FRP debonding is considered within the CSCT model, the theory can predict the slab’s overall behavior, load-bearing capacity, and failure mode with acceptable accuracy. Therefore, in this study, the yield line theory was employed to account for FRP debonding in slab analysis. In addition, the provisions of ACI 318, EC2, and MC 2010 were examined to predict the specimens’ behavior. Among these codes, the MC 2010 provisions—which are based on CSCT—showed the best performance in estimating the punching shear capacity and the failure modes of the tested slabs.

Keywords

Main Subjects

Journal of Civil and Environmental Engineering

Articles in Press, Accepted Manuscript
Available Online from 28 July 2026

Files

Share

How to cite

Statistics