Sustainable Refurbishment of Existing Bridges.
SUREbridge is a software solution for the Sustainable Refurbishment of Existing Concrete and Steel-Concrete Bridges.
The software tool is especially developed for:
- Engineering service company
- Structural designer
- Infrastructure Administration
- Road Authorities
The software SUREbridge evaluates the resisting bending moment of concrete bridge sections strengthened with carbon fibre-reinforced polymer (CFRP) laminates and/or glass fibrereinforced polymer (GFRP) panels. The section to be strengthened is assumed to be made of either reinforced or pre-stressed concrete or a combination of both.
The potentiality of SUREbridge has been demonstrated through the structural analysis of a case study bridge.
The key of the technique is the combined use of GFRP panels, installed on the top of the existing deck, and pre-stressed CFRP laminates, applied to the bottom of the longitudinal girders.
Separate use of CFRP laminates or GFRP panels alone could reaching the same load-carrying capacity, but with major problems, such as the need for very thick panels or an excessive number of laminates.
The excellent strengthening capacity of the combined CFRP-GFRP application was further demonstrated through laboratory tests on full-scale prototype beams, whose results were also successfully predicted through non-linear finite element analyses.
But, what is the aim of SUREbridge?
The aim of the SUREbridge project is to provide an alternative solution to utilize the remaining capacity of the concrete deck in an existing bridge.
Due to the expected increase in the traffic volume in Europe, existing bridges will be subjected to more severe actions in the near future. Consequently, the need to refurbish these infrastructures, often structurally deficient and obsolete, will increase dramatically.
At present, construction and maintenance activities relating to bridges imply costly and time-consuming procedures, with a negative impact on traffic flow and welfare in wider terms. In addition to disturbance to users, traffic disruption, and pollution, other issues are the inefficient use of resources, i.e. materials and energy, waste management, and recycling.
Within the above described context, the European research project SUREBridge – Sustainable Refurbishment of Existing Bridges, has developed an innovative strengthening technique for reinforced concrete and steel-concrete bridges. The high strength and stiffness properties of composite materials are suitably exploited to increase the load-carrying capacity of existing bridge decks, while minimising demolition work and waste production.
How it works?
The GFRP panels can be manufactured of the same width or wider than the existing deck, enabling to widen the road section if needed.
The GFRP sandwich panels are manufactured by FiberCore Europe with the InfraCore® Inside patented technology, comparable to vacuum infusion. It provides a strong, lightweight structure with integrated resistance to delamination, impact, blast, and fatigue, which are major issues affecting other commercially available composite sandwich panels. In this respect, it should be noted that fatigue and delamination are relevant failure modes for road bridges bearing repeated traffic loads with heavy wheel imprints.
Low additional weights, specific design possibilities per single bridge, easy installation, and little maintenance costs are other winning features of the InfraCore® Inside panels and of the whole SUREBridge technique.
The CFRP laminates are pre-stressed by using an innovative technique, which avoids stress peaks in the CFRP-concrete interface, thus preventing early delamination.
Thanks to a special device developed at Chalmers University Technology, the magnitude of the shear and peeling stresses at the laminate anchor points is kept to a level which can be tolerated by the adhesive and concrete substrate. This technology overcomes the tendency of the laminate to debond already at low stress levels, with horizontal shear cracks propagating from the concrete support ends. It should be stressed that this is achieved with no need for mechanical anchors, which typically imply different drawbacks, such as the weakening of existing structural members, installation and inspection difficulties, and extra costs.
To prove the effectiveness and feasibility of the proposed technique in real-life applications, an existing bridge located in the municipality of San Miniato (Pisa), Italy, was selected as a case study.
A clear demonstration of the high strengthening capacity of the proposed technique was given through fullscale tests on T-shaped cross-section prototype beams.
The bridge project of San Miniato was developed by AICE Consulting, engineering company based in Pisa and founded in 1990 that provides high-tech engineering services for the construction sector both nationally and internationally.
For more details about the features of software or the project, please, visit the SUREbridge website.