A new concept for sustainable refurbishment of existing bridges using FRP materials

This paper presents a new strengthening concept proposed for road bridges in the project SUREBridge (Sustainable Refurbishment of Existing Bridges), co-funded by the European Commission through the ERA-NET Plus Infravation 2014 Call. The project proposes an innovative and holistic refurbishment approach by using fiber-reinforced polymer (FRP) materials. The approach is designed for bridge upgrading, including repair and strengthening actions in the most effective and efficient way in terms of reducing construction time, resource consumption, and traffic disruption. SUREBridge concept consists of bonding prestressed carbon fiber reinforced polymer (CFRP) laminates to the tensile parts of flexural members (such as bottom flange of girders), and installing glass fiber reinforced polymer (GFRP) panels to the compressive parts (such as top of the existing concrete deck). A novel prestressing system is used to apply prestressed CFRP laminates eliminating the need for mechanical anchorage of the composite strips. The GFRP panels contribute by increasing the overall bending stiffness of the section and unloading the compressive concrete which might not be in a good condition. The GFRP panels are fabricated in a robust modified sandwich-type that ensures load-spreading onto the concrete. The bespoke design of the decks allows for widening the bridge and the incorporation of a curb to avoid further water ingress to the concrete substructure. The effectiveness of the proposed technique is demonstrated through lab test of the stepwise prestressing method and a case study of strengthened prototype beams. Furthermore, a theoretical model has been set up to predict the strengthened cross section’s ultimate bending moment.