Behavior of Carbon Fiber-Reinforced Prestressed Concrete Skew Bridges

A new design and construction technique using carbon fiber-reinforced polymers (CFRP) prestressing tendons for skew highway bridges is presented in this paper. Two multiple double-T (DT) skew bridge models with 30 and 15 degree skew angles were constructed and tested. CFRP reinforcing rods and stirrups were used for flexural and shear reinforcement of the deck slab and the DT-girders. Internally bonded and externally unbonded draped CFRP tendons were used for prestressing in the longitudinal direction. CFRP tendons were also used for prestressing in the transverse direction. Conventional DT girders were modified by adding tendon deviators and cross beams through which the transverse prestressing was applied. The two bridge models were tested under static, repeated (7 million cycles), dynamic, eccentric, and ultimate loads. The effects of repeated load on the static and dynamic responses of the bridges and load distribution were examined. The influence of grouting the transverse CFRP prestressing tendons on the load distribution was also investigated. The skew bridges designed and constructed using the described technique performed well during all phases of testing. The repeated load had no adverse effect on the dynamic and static characteristics of the tested skew bridges, and an insignificant effect on the load distribution in the transverse direction. None of the externally draped prestressing tendons experienced rupture under repeated or ultimate loads. Transverse load distribution exhibited the same characteristics whether the transverse prestressing tendons were bonded or not.