Flexural behavior of over-reinforced beam with ECC layer: Experimental and numerical simulation study

To optimize the brittle failure of reinforced conerete (RC) over-reinforeed beams and enhance their flexural performance, a novel structural form is proposed. To be specific, the Engineered Cementitious Composite (ECC) layer is installed on top of the RC over-reinforced beam (ERCOB). A total of six test beams are prepared, comprising one unreinforced beam and five reinforced beams. The variables comprised the depth of the ECC, reinforcement ratio, and whether the ECC is configured at the bottom. The test findings are subsequently compared with simulation outcomes to validate the model's precision. Next, the influence of various variables on ERCOB flexural performance, such as load-deflection response, bearing capacity, etc., is deeply analyzed. The research indicates that the ECC applied to both the top and bottom of the specimen exhibits enhanced bearing capacity and ductility. In comparison to CB-1, the maximum load and deflection ductility coefficient of EB-2 increased from 45.73 kN to 2.63-48.52 kN and 3.85, representing increases of 6.1 % and 29.6 %, respectively. It reveals that ECC layer improves the defects caused by excessive reinforcement of over-reinforced beams, and optimizes the tensile capacity of the steel bars, thus improving the bending capacity and ductility of the specimens. Finally, the prediction model of ERCOB flexural capacity is proposed to further verify the effectiveness of ERCOB. This study not only verifies the effectiveness of ECC reinforcement, but also helps to delay the failure process of structures, provide reference for future engineering application design.