Numerical investigation on the flexural behavior of GFRP reinforced concrete beams with CFRP grid-reinforced engineered cementitious composites

Glass fiber-reinforced polymer (GFRP) reinforced concrete beams can be effectively strengthened and made more durable using carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cement composite (ECC). However, the bearing mechanism and design formula for the flexural capacity of this type of hybrid beam are not yet clear. Hence, it is necessary to conduct a thorough study on it through numerical analysis. In this paper, a series of refined finite element (FE) models were established and verified by comparing the failure modes and load-displacement curves with experimental results. The mechanical behaviors of GFRP bars, steel bars, CFRP grids, concrete, and ECC were analyzed in depth. Then, the effects of some key parameters on the flexural behavior of the hybrid beam were investigated, including the compressive strength of the concrete prism, diameter of GFRP bars, tensile strength of ECC, cover thickness of ECC, and cross-sectional area of CFRP grid. Finally, a new formula for the flexural capacity of the hybrid beam was proposed based on the plane-section assumption, and its accuracy was verified by both experimental and numerical findings. The results showed that the contribution of the combined concrete and ECC to the flexural capacity of the beam was 43.45% at peak load. The proposed formula accurately predicted the flexural capacity of the hybrid beam and can be applied to other beams of similar formations.

Automated summary

Through numerical analysis, the bearing mechanism and design formula for GFRP reinforced concrete beams with CFRP grid-reinforced ECC were studied. Refined FE models were established and verified by comparing with experimental results. The mechanical behaviors of GFRP bars, steel bars, CFRP grids, concrete, and ECC were analyzed in depth. The effects of key parameters on the flexural behavior of the hybrid beam were investigated and a new formula for flexural capacity was proposed and verified.