Numerical and theoretical investigations on flexural behavior of two-way RC slabs strengthened with BFRP grid-ECC composites

Abstract

This paper delves into the flexural behavior of reinforced concrete (RC) two-way slabs strengthened with basalt fiber reinforced polymer (BFRP) grid and engineered cementitious composite (ECC). Building upon a prior comprehensive experimental investigation on slabs strengthened with BFRP-ECC composites, this study focuses on developing reliable strength models through the proposal of accurate finite element (FE) models. By meticulously comparing failure modes, load–deflection responses and strain developments of steel reinforcements and BFRP grids between FE predictions and experimental observations, the efficacy of the FE model in accurately predicting test results is demonstrated. The average ratio of the predicted to experimental ultimate load is 1.02, with a coefficient of variation of 0.041. A subsequent parametric study shed lights on key factors influencing the flexural performance of these strengthened slabs. It turned out that increasing ECC thickness significantly enhanced the flexural capacity, with an improvement ranging from 30.2% to 140.2%. Furthermore, a design-oriented model, incorporating the development of yield line and uniformity of BFRP strain is introduced, effectively capturing the ultimate load and moment of strengthened slabs. This research not only advances the understanding of the strengthening mechanism but also offers practical insights for designing and assessing such composite systems.