Salvador J. E. Dias

Shear Strengthening of RC Beams with Near-Surface-Mounted CFRP Laminates

Synopsis: The efficacies of the Near Surface Mounted (NSM) and Externally Bonded Reinforcing (EBR) techniques for the shear strengthening of rectangular cross section RC beams are compared. Both techniques are based on the use of carbon fiber reinforced polymer (CFRP) materials. The NSM was the most effective technique, and was also the easiest and fastest to apply, and assured the lowest fragile failure modes. The performance of the ACI and fib analytical formulations for the EBR shear strengthening was appraised. In general, the contribution of the CFRP systems predicted by the analytical formulations was larger than the values registered experimentally. The capability of the De Lorenzis formulation of predicting the contribution of the NSM technique for the shear strengthening of RC beams was appraised using bond stress and CFRP effective strain values obtained in pullout bending tests. This formulation provided values 61% lower than the values obtained experimentally.

New Shear Strengthening Configurations of Near-Surface- Mounted CFRP Laminates for RC Beams

QREN (through the Operational Program COMPETE) in the scope of the CutInov Project (n. 38780) involving the Clever Reinforcement Company and the Structural Composites Research group of ISISE-Minho University

Influence of the concrete properties in the effectiveness of the NSM CFRP laminates for the shear strengthening of RC beams

The New Surface Mounted (NSM) technique was applied to increase the shear resistance of Reinforced Concrete (RC) beams. For this purpose, laminates of Carbon Fiber Reinforced Polymer (CFRP) were introduced into thin slits made on the concrete cover of the lateral faces of the beams to be strengthened. In the present paper the influence of concrete strength on the effectiveness of the NSM technique is assessed by an experimental program. From the obtained results it can be concluded that the NSM shear strengthening technique with CFRP laminates is still effective in RC beams with low concrete strength. However, as mini- mum is the concrete strength as less effective is the NSM technique.