Cellular Automata for Corrosion in CFRP-Strengthened Bridge Columns
Jun Wang, Yail J. Kim
Appears on pages(s):
carbon fiber-reinforced polymer (CFRP); cellular automata; column; corrosion; model; rehabilitation; strengthening
This paper presents the durability modeling of bridge piers subjected to corrosive environments, including atmospheric, splash, and submerged conditions, for a service period of 100 years. Two types of reinforced concrete columns are utilized, cast-in-place and accelerated bridge construction (ABC), and their time-dependent performance is predicted by von Neumann’s square lattice in conjunction with a novel evolutionary mathematics approach called cellular automata. The capacity of the corrosion-damaged columns is upgraded using carbon fiber reinforced polymer (CFRP) sheets. Depending upon concrete strength and construction method, chloride migration mechanisms are evaluated to elucidate the variation of diffusion coefficients, chloride concentrations, and other corrosion-related issues for those columns with and without CFRP confinement. For the first 30 years, the chloride diffusion of the ABC column is slower than that of the cast-in-place column; otherwise, no difference is noticed. Under the splash condition incorporating periodic wet-dry cycles, chloride concentrations remarkably increase relative to other exposure environments, particularly for the cast-in-place column. The development of corrosion current density is dominated by the pore structure of the concrete, and the corrosion initiation of the ABC column takes 4.3 times longer compared with its cast-in-place counterpart. At 100 years, the capacity of the cast-in-place and ABC columns decreases by 28.1% and 23.2%, respectively, primarily due to the impaired concrete near the degraded reinforcing bars in a corrosion influence zone. The columns’ responses are enhanced by CFRP confinement in terms of toughness, energy dissipation, load-carrying capacity, and load-moment interactions.