Numerical Investigation of FRCM-Strengthened Corroded RC Beams under Cathodic Protection

Abstract

Fibric reinforced cementitious matrix (FRCM) composites have been used to improve the mechanical performance of reinforced concrete beams subjected to degradation in the past decades. Recently, dual-functional carbon fibres have been explored to provide both structural strengthening to RC beams and cathodic protection to reinforcement bars. This paper investigates the loading responses and structural behaviour of RC beams subjected to different levels of corrosion, protected by impressed current cathodic protection and structurally strengthened by external bonded FRCM. A numerical model is developed for the corroded RC beams under impressed current cathodic protection and structural strengthening by the FRCM composite. Upon validation against experimental results collected from the literature, the finite element model is then used for parametric study. A number of numerical results are generated to analyse the effects of key parameters, including the corrosion rate, degradation level of interfacial bonding properties due to anode acidification, and end anchorage, followed by detailed discussions. It is found that the significance of the corrosion of steel reinforcement bars significantly affects the load-carrying capacity of the beams. Increasing the corrosion rate from 0 to 40% reduces the load-carrying capacity of un-strengthened beams to 45% of the original capacity. Therefore, the cathodic protection provided by the C-FRCM plate is important to the reinforcement bars as it can avoid the cross-section area reduction of reinforcement bars and, thus, the main loading capacities of the beams. In this study, the degradation of the bonding properties at the interface of carbon fibre and the cementitious matrix due to anode acidification during impressed current cathodic protection is also considered. It is found that the bond strength of the C-FRCM plate has a slight effect on the load-carrying capacity of the beam. In addition, the application of end anchorage can significantly enhance both the load-carrying capacity and ductility of the beams. The rates of enhancement, if compared to the beams with no end anchorage, can reach up to 60%.

Bending behaviour of corroded RC continuous beams with C-FRCM strengthening system

“…The bond-slip interaction at the interface between the C-FRCM plate and concrete beam, which has not been considered in previous numerical investigations [32,33,35,36], was considered herein to obtain the mechanical behaviour of the RC beams more accurately. The interface between the C-FRCM plate and the concrete is essentially the interface between the cementitious matrix and the concrete.…”

“…Therefore, the definition and simulation of the interface between the aforementioned components are essential to reproduce the test failure modes, and influence the ultimate capacities. However, these interface simulations have not been thoroughly considered in the existing FE studies on RC structures [32][33][34][35][36].…”