The issue of upgrading existing structures has been of great importance over the last decades due to their deterioration; ageing, environmental induced degradation, lack of maintenance or need to meet the current design requirements. Replacing the deficient concrete structures in the near future with new is not a viable option as it would be prohibitively expensive. For this reason a shift from new construction towards renovation has been witnessed in the European construction sector, between 2004 and 2013, with practically 50% of the total construction output being renovation and structural rehabilitation.
Fibre reinforced polymers (FRP) have been widely used as externally bonded (EB) reinforcement of existing structurally deficient structures over the last three decades due to their favourable properties (i.e. high strength to weight ratio, corrosion resistance, ease and speed of application, and minimal change of geometry). However, the FRP strengthening technique entails a few drawbacks mainly associated with the use of epoxy resins. In particular, except from their high costs and their inability to apply on wet surfaces, FRP have very poor performance at high temperature as under loading epoxy resins normally lose their tensile capacity. In an attempt to alleviate the problems arising from the use of epoxies, researchers have introduced a novel composite material, namely textile-reinforced mortar (TRM), which combines advanced fibres in form of textiles (with open-mesh configuration) with inorganic matrices, such as cement-based mortars. Over the last decade it has been reported in the literature that TRM is a very promising alternative to the FRP retrofitting solution.
Shear strengthening of RC beams or bridge girders in old RC structures is one of the most common needs when assessing their strength under the current code requirements. This is due to insufficient amount of shear reinforcement, corrosion of existing shear reinforcement, low concrete strength and/or increased design load. Therefore, the last ten years many researchers were investigated the use of TRM jacketing for shear strengthening of concrete beams.
Aim of this project is the development of a design model for the calculation of the contribution of the TRM jacketing to the shear resistance of concrete beams.