Title: Complexity Modeling of Corrosion in Carbon Fiber- Reinforced Polymer-Retrofitted Concrete Bridge

Author(s): Yail J. Kim and Jun Wang

Publication: Structural Journal

Volume: 119

Issue: 4

Appears on pages(s): 3-18

Keywords: bridge; carbon fiber-reinforced polymer (CFRP); complexity; durability; rehabilitation; strengthening

DOI: 10.14359/51732645

Date: 7/1/2022

Abstract:
This paper presents an analytical investigation into the kinetics of chloride and its ensuing potential for diffusion-driven corrosion in a two-span solid-slab highway bridge, including capacity reductions and strength recovery using carbon fiber-reinforced polymer (CFRP) composites. An open-source complex systems solver, processing mutual interactions between discrete entities (agent-based modeling), is used to predict the movement of chlorides in the spatial and temporal domains of the reinforced concrete superstructure at variable cover depths. Three exposure conditions (splash, deicing, and coastal) are modeled to represent corrosive environments during a service period of 100 years. A complexity index is defined on the basis of Shannon’s entropy and quantifies the degree of disorder in a diffusion process. The efficacy of strengthening the corrosion-damaged bridge with CFRP sheets is elaborated. The diffusion coefficients of chlorides decline with time, while the rates become stable and independent of concrete strength after 20 years. Depending upon the distance from the concrete surface, a response transition is noticed in chloride concentrations owing to the transferred intensity of equilibrium chlorides. The corrosion current density of the reinforcement is influenced by the exposure conditions and cover depths. Complexity indexes belonging to the splash condition are higher than those of other conditions, which are dictated by the concrete strength. The concrete cover controls the migration of chlorides, thereby affecting the initiation and progression of corrosion damage, and the presence of an effective propagation depth is substantiated. The capacity reduction of the superstructure is noticeable under the deicing condition compared with those under the splash and coastal conditions. The enhancement of the bridge’s flexural capacity with CFRP strengthening is a function of the concrete strength and cover depth.