PERFORMANCE EVALUATION OF BRIDGES WITH FIBER REINFORCED COMPOSITE DECKS

The Stelzer Road Bridge in Columbus, Ohio underwent deck replacement in 2000-2001 with a traditional reinforced concrete deck for northbound traffic lanes and a fiber-reinforced composite tube deck with prestressed concrete filling each tube for use by southbound vehicles. The two decks were built side-by-side enabling an effective comparison of the structural performance between the two systems. The project stakeholders formulated a testing program that included laboratory and field testing. Laboratory testing included determination of the composite beam's coefficient of thermal expansion and its stiffness using a three-point bend test. The fiber reinforced polymer composite's coefficient of thermal expansion did not satisfy the bridge specifications. The field testing of deck deflection and strain was also broken into two parts: a series of controlled tests using trucks with known loads allowing for direct comparison of performance of the two decks and monthly random traffic readings. Results for known loads indicated composite deck deflections higher by an average of 43% than the conventional deck, indicating possible deficiencies in the composite deck. Monthly readings were consistent with the known load tests as the conventional deck outperformed the composite deck. Also observed was the composite deck's declining performance in warmer weather probably due to the thermal expansion problem. Visual field observations were also made after unexpected cracking in the composite deck's sidewalk and median occurred within one month of the deck's completion. For comparison purposes, the condition of the sidewalk and median of the concrete deck were inspected and significantly less cracking was found on the concrete side. Also examined were the effects of temperature changes on the composite deck in light of the coefficient of thermal expansion results. Comparisons were also made in areas central to the field of construction: cost and labor time. While taking about 50% less installation time, construction costs of the composite deck were higher than for the traditional deck by a factor 2.7. Issues involving fabrication and construction of the composite deck are also discussed.