ABSTRACT
ABSTRACT: This paper presents the construction details and field testing results of six innovative FRP reinforced concrete bridges recently constructed in North America. Five bridges, Wotton, Magog, Cookshire, Val-Alain, and Melbourne Bridges are located in Quebec, Canada, while the sixth one, Morristown Bridge, is located in Vermont, USA. All six bridges are girder-type with main girders made of either steel or prestressed concrete. The main girders are supported over spans ranging from 26.2 to 50.0 m. The deck is a 200 to 230 mm thickness concrete slab continuous over spans of 2.30 to 3.15 m. Different methods to design the deck slabs of the six bridges were used. As a result, different types of glass and carbon FRP reinforcing bars and conventional steel were used as reinforcement for the concrete deck slab. The six bridges are located on different highway categories, which mean different traffic volume and environmental conditions. The bridges are well instrumented at critical locations for internal temperature and strain data collection using fibre optic sensors. These gauges are used to monitor the deck behaviour from the time of construction to several years after the completion of construction. Except Melbourne Bridge, all bridges were tested for service performance using calibrated truckloads running in different paths that produce maximum strains in both of the concrete and reinforcement. Both static and dynamic loading, while the trucks travels at different speeds, were carried out. The construction procedure, field tests and monitoring results, under real service conditions, showed very competitive performance to concrete bridges reinforced with steel. The FRP-reinforced bridge decks are very well performing under very harsh environment (de-icing salts, freeze/thaw cycles, elevated temperature, and heavy traffic). No additional or propagation of cracks, if any, were observed under these severe service conditions. The serviceability performance of the concrete deck slab reinforced with FRP bars in terms of strain, cracking, and deflection was very similar to that reinforced with steel bars. During the entire tests, the maximum tensile strain in FRP bars was less than 0.5% of the ultimate strain of the material. For bridges with either concrete or steel girders, the concrete deck slab reinforced with FRP bars can distribute the truck loads over girders approximately the same as concrete deck slab reinforced with steel bars. Finite element modeling and analysis were carried out to investigate the effect of using a reduced amount of reinforcement on the service and ultimate behaviour of the bridges. The FEM shows that the proposed reinforcement ratios adopted by the updated version of Section 16 of CHBDC are adequate for satisfying the serviceability and the strength criteria.
