Toolbox for flexible refurbishment of existing bridges
A large number of European bridges are in need for maintenance and upgrading. The upgrading activities for bridges usually involve strengthening and repair. Maintenance and upgrading of bridge structures is usually associated with traffic restrictions in form of complete or partial traffic disruptions. Traffic disruption, especially in in urban areas is one of the most challenging issues that road authorities have to deal with. In densely populated areas, the indirect cost of upgrading, i.e. strengthening and repair, could easily over take the direct cost of the project. Traditional materials and techniques are usually not efficient and often time consuming. Results of inquiries from road authorities in Pantura project revealed that (1) minimizing traffic disruption, (2) minimizing application time, (3) minimizing initial costs, (4) better long-term performance and lower maintenance costs are the priorities when it comes to strengthening and repair methods for bridge structures. Increase in the number of deficient bridges, in one hand, and limited financial resources in the other hand, call for more efficient materials and techniques, therefore, there is a large demand for developing new materials and techniques which are better and more efficient compared to traditional materials and methods. The current document presents deliverable D5.20 in WP5 which addresses task 5.2. This task aims at Developing new and improving existing strengthening and repair techniques so that they lead to; (1) shortening the application time and therefore less traffic disruption, (2) better material usage and higher efficiency and (3) application of new construction materials which have better durability properties and thus reduced LCC. The focus of the work in D5.20 has been on both developing innovative solutions and implementing innovation to solve problems and/or overcome existing shortcomings associated with existing solutions. The core of the work in this deliverable is to use fiber reinforced polymer, FRP, materials in upgrading of bridge structures due to advantages that they offer compared to traditional strengthening and repair materials and techniques (D5.8). The FRP bonding technique has been around since 1970th and attracted a lot of attention as an effective and economic solution for strengthening and repair of structural elements. Numerous bridges have been upgraded using this technique around the world, providing evidence for effectiveness and viability of this method. However, using FRPs is associated with some shortcomings and there is still a need for research and improvements. Issues such as high initial cost of the material, lack of design codes, quality control during application are among the hinders. In this regard, several shortcomings have been identified in WP5 and attempt has been made to solve them. Solving these problems would certainly lead to a greater acceptance of this technique among the authorities and bridge owners. The results of the research in task 5.2 have been presented as a collection including a new design model for adhesive joints in flexural steel members, application of an innovative FRP T-profile for strengthening of concrete members, a new method for using pre-stressed FRP laminates for strengthening and repair of concrete structures, recommendations on using geometrical modifications in adhesive joints and a method for fast curing of adhesive joints in order to reduce the strengthening and repair operation time. Experimental verifications and field applications have been carried out to prove the applicability of the proposed techniques.