Mechanics model, FE analysis, and experiment for shear behaviour of LWC beams strengthened with innovative configurations of ULW-ECC

This paper presents a comprehensive study on the shear behaviour of reinforced lightweight concrete (LWC) beams strengthened with ultra-lightweight engineered cementitious composite (ULW-ECC) reinforced with fibrereinforced polymer (FRP). Nine beam specimens were tested, focusing on main parameters such as ULW-ECC arrangements and FRP mesh types. It was concluded that various ULW-ECC arrangements exhibited varying strengthening efficiency owing to the different shear transfer mechanisms. Subsequently, a robust finite element (FE) model was established, showing good agreement with experimental results across all details. Based on the established FE model, a parametric study was conducted to evaluate the most influential factors on shear strength capacity, concluding that the compressive strengths of LWC and ULW-ECC had different effects on shear strengths depending on the ULW-ECC arrangement. Finally, a theoretical shear strength model based on the truss-arch model was developed. The accuracy was verified using the experimental results in this paper as well as previous studies and numerical results.