Finite element modelling of reinforced concrete beam strengthening using ultra-high performance fiber-reinforced shotcrete combined with reinforcing bars

Ultra-high performance fiber-reinforced shotcrete (UHPFRS) is advanced concrete material for strengthening and repairing concrete structures, especially in narrow and difficult-to-access places. However, there has been little quantitative analysis of its strengthening capacity for concrete structures. Therefore, this paper develops a Finite Element (FE) model to simulate the structural behavior of reinforced concrete (RC) beams strengthened by a UHPFRS layer. The traction-separation model combined with the concrete damaged plasticity (CDP) model can accurately simulate the structural behavior of the NSC-UHPFRS composite beam by calibrating and validating with experimental results. Based on this FE model, a parametric study is conducted to asset the effect of the height, reinforcement ratio, and fiber orientation of the UHPFRS layer on the strengthening capacity of UHPFRS for the RC beam. The findings show that those parameters significantly impact the composite beam's load-displacement characteristics. It also contributes to a better understanding of applying UHPFRS in strengthening RC beams as well as structures to extend the service life effectively.