Distressed Adjacent Prestressed Concrete Voided Beams at the End of Service

Abstract

Bridge superstructures built with adjacent precast concrete voided members have the advantages of low profiles, faster construction times, no requirement for deck formwork, and the consequent reduction of the duration of workers’ exposure to construction vehicles and traffic. These reasons make this type of construction a preferred design. However, the mechanism that transfers load between adjacent beams often cracks, leading to leakage of salt-laden water runoff between the individual beams and to corrosion of the reinforcement. Two bridges in Virginia provide a contrast in performance: one box beam structure that was highly deteriorated after 31 years of service, and one adjacent voided slab bridge that was in relatively good condition after more than 50 years of service. Researchers conducted both destructive and nondestructive evaluations of beams from these structures, including in situ assessment of the concrete and prestressed reinforcement and sampling of the concrete core. Maintenance practices, concrete quality, and construction quality control appear to be the major factors influencing the conditions of these structures. Recommendations are provided to help prevent premature deterioration in future designs using adjacent precast concrete voided members.