The 19th Avenue Bridge is a typical three-span continuous reinforced concrete slab bridge found in the city of Phoenix, Ariz. One of the many bridges spanning the Phoenix canal system, the structure carries an estimated average daily traffic of 30,000 vehicles. As with any concrete bridge constructed in the 1940s, this bridge was designed to accommodate traffic loads lighter than currently permitted and was approaching the end of its service life, demanding an immediate upgrade.
Problem: A major challenge was to replace the bridge with limited environmental pollution, limited construction time, minimal traffic disruptions, and most importantly, a reasonable construction cost for total replacement.
Solution: In lieu of replacement, the Gannett Fleming design team creatively produced a strengthening concept that is environmentally sensitive with minimal impacts to traffic. The concept involved the novel strengthening technique using externally bonded CFRP composite materials. The sustainable approach of employing CFRP greatly reduced costs while achieving the required load carrying capacities. In addition to the speed and ease of installation, which required minimal labor and traffic interruptions, the total cost of the bridge rehabilitation was $800,000 including design effort. With a $4 million estimate for a total bridge replacement, the use of CFRP materials resulted in a savings of more than $3.2 million to the city of Phoenix. The entire scope of the project was completed on budget and within the time constraints of the three-week canal dry-up period.
Carbon fiber reinforced polymer (CFRP) composite materials have revolutionized bridge rehabilitation projects. These innovative materials enable concrete structures to be upgraded through a fast-paced approach that is environmentally responsible, cost-effective, and does not cause traffic congestions or delays. 