Behavior of concrete voussoir flexible arch bridges reinforced with FRP composites

Flexible arch bridges, which can be pre-fabricated, transported and assembled on-site, have become increasing popular. This study presents an experimental investigation into the behavior of concrete voussoir flexible arch bridges reinforced with fiber-reinforced polymer (FRP) sheets by loading four arch specimens to failure at their left third-spans. The variables included the concrete voussoir strengths, bond quality between FRP and concrete voussoirs, and the FRP reinforcement locations. The results showed that two specimens with good bonding between FRP sheets and concrete voussoirs failed from sudden FRP rupture, while the other two specimens experienced FRP debonding and ultimately exhibited a four-hinge collapse mechanism. For the specimens with good FRP bonding, the typical load-deflection curve obtained at the loading point was an approximately monotonic increasing line, while load reductions and recoveries, as well as slope deteriorations were noted for the specimens experienced FRP debonding. It is also compared that bond quality could be more important than concrete voussoir strength, as the specimens with good bonding had higher ultimate load capacities. Applying one additional FRP sheet at intrados of arch could significantly enhance the initial ascending slope by 100%, but it cannot enhance the peak load as the FRP sheet at extrados of arch was more efficiently utilized in preventing more hinge formations at extrados joints.