More than 42% of U.S. bridges are now more than 50 years old, according to ASCE’s 2021 Report Card for America’s Infrastructure. These older bridges are not necessarily unsafe, but regular traffic demands combined with deterioration agents that corrode steel-reinforced materials can put concrete bridge decks at risk. These bridges are at a higher risk of future closures or weight restrictions and thus they require investment in the form of replacement or significant rehabilitation. Past construction projects frequently focused only on the initial construction costs and not the long-term maintenance costs, therefore discounting some corrosion-resistant materials as cost prohibitive.
In “Streamlined Framework to Select Corrosion-Resistant Reinforcement to Balance Life-Cycle Costs and Ductility of Concrete Bridge Decks,” researchers Matthew J. Gombeda, Zoe N. Lallas, and Estevan Rivera Jr. focus on the full life-cycle costs for concrete bridge deck reinforcement to identify the optimal type of reinforcement. An extensive literature review by Gombeda of the types of steel bars (including the popular epoxy-coated, stainless steel, and several others), their corrosion resistance, and repair costs, helped jump start development of this framework. For this paper, the team used two methodologies to estimate costs. The first was a theoretical approach on the present-value calculation, and the second was a simpler methodology factoring in uniform repair and material costs over three 25-year milestones in the lifespan of the bridge. The authors applied their framework using two case studies, one on a congested bridge in the Chicago suburbs with regular daily traffic, and the second on a rural interstate bridge. Learn more about this framework and how departments of transportation, government agencies, and engineering firms can apply these frameworks to estimate bridge deck life-cycle costs over the structure’s lifespan in the Practice Periodical on Structural Design and Construction at https://doi.org/10.1061/PPSCFX.SCENG-1527. The abstract is below.
Abstract
This paper presents a streamlined and simplified framework to select the optimal corrosion-resistant reinforcement type and subsequently calculate the corresponding life-cycle costs for concrete bridge decks. Additionally, a design-oriented methodology that accounts for the effect of high-strength reinforcement, most notably reduced ductility and its implications on structural safety decision-making, is also included as part of the framework. The researchers developed a design-friendly high-strength reinforcement factor that is predicated on the net tensile strain of the high-strength reinforcement relative to the corresponding value of an equivalently designed bridge deck using conventional reinforcement. The framework provides two approaches for estimating life-cycle costs; the first adopts a theoretical present-value calculation from previous researchers, and the second serves as a simplified approach that directly superimposes material and repair costs over the intended service life. Example life-cycle cost estimates are then shown for a series of corrosion-resistant bar types including epoxy-coated; galvanized; stainless steel; and high-strength low-carbon, chromium (A1035) bars. A case study focusing on the ductility of high-strength reinforcement then provides further recommendations for implementing such bars into the larger framework. Lastly, two example bridge deck scenarios are highlighted to demonstrate the implementation of the proposed framework. The framework is designed to facilitate straightforward optimal design solutions for department of transportation (DOT) officials, consulting engineers, and others, for bridge deck applications where enhanced corrosion resistance is necessitated and access to more theoretical life-cycle cost methodologies is limited.
Get details on this framework and how you can apply it today in the ASCE Library: https://doi.org/10.1061/PPSCFX.SCENG-1527.
