Numerical Analysis on Flexural Shear Behavior of Reinforced Concrete Beams Strengthened with Fiber-Reinforced Polymer Grid and Engineered Cement Composites

Strengthening reinforced concrete (RC) beams with fiber-reinforced polymer (FRP) grids and engineered cement composites (ECCs) can significantly enhance their shear capacity. However, the specific contributions of the components in reinforced RC beams remain unclear, necessitating further investigation into the flexural shear performance of RC beams. The numerical model was used to analyze the flexural shear performance of RC beams strengthened with an FRP grid and ECCs. Subsequently, the parameters affecting the flexural shear performance of beams were discussed. This included the compressive strength of concrete prism, the shear span ratio, the tensile strength of ECCs, the thickness of the ECC cover, the cross-sectional area of the FRP grid, and the number of FRP grid layers. Finally, a calculation formula was established to predict the shear capacity and verified by the outcomes from numerical models and experimental data. The findings indicated that the ECC-strengthened layer significantly contributed to increasing the shear capacity. Additionally, the FRP grids helped to reduce stress concentration in the flexural shear zone, thereby preventing premature concrete cracking. The max load increased by 8.06% when the ECC’s tensile strength increased from 4 MPa to 10 MPa. In addition, increasing the cover thickness from 8 mm to 20 mm caused the peak load to increase by 14.42%. The calculation formula introduced in this research accurately predicts the shear capacity of the oblique section of RC beams.