Effectiveness of CFRP jackets in RC rectangular columns. Full-scale experimental study

The effectiveness of carbon FRP jackets in improving the axial compressive strength and deformation capacity of reinforced concrete (RC) members has been studied by means of an extensive full-scale experimental programme. Nineteen RC specimens with a height equal to 2400 mm of square and rectangular cross-section with a concrete compressive strength of around 20 N/mm2 were tested. In the study the aspect ratio between the section sides (h/b), the corner radius (Rc) and the number of CFRP plies were varied. It is observed that increasing Rc or the number of CFRP layers allows for improvements to the resistance capacity, yet only when this is combined with other parameters favourable to the confinement action. A maximum strength improvement of 1.16% and 0.71% was obtained for square and rectangular columns. Regarding the failure mode, the appearance of wrinkles in the CFRP jacket prior to the fibres’ rupture could be considered as a warning of a column failure. With respect to mechanical behaviour, for the full-scale rectangular specimens tested was not frequent as to obtain an ascending stress-strain curve. The lateral strains recorded along the cross-section show the uneven distribution along the non-circular section's perimeter. This information contributes to increasing the database of large-scale test results, which is far from extensive on this topic.