Ductility of RC Columns confined with FRP Sheets

Many existing structures show insufficient seismic capacity, with the lack of members' ductility being a critical factor. Aim is to manage to increase their ductility, through confinement with composite fiber reinforced polymer (FRP) sheets. In the present paper, available analytical procedures of Eurocode 8-Part 3 (2005) and draft of 2022 and the Greek Code for Structural Interventions (CSI) of 2013 and the revision of 2022 are examined, compared together with an analytical model proposed in the literature. Analytical results of the above procedures are also compared both with available experimental data and with each other and the degree of their reliability is evaluated. The current EC8-3 (2005), although in many cases converges quite well with the experimental data, unrealistic results are obtained for a large thickness of the confined material. This seems to be corrected in the proposed EC8-3 revision of 2022. The Greek CSI 2013 adopts a very simple straight-forward analytical procedure producing the most conservative results, while the revised analytical expressions included in the 2022 version, has a better convergence with the experiments. However, for large thickness of confinement material, the ductility factor values are unrealistically high. The model proposed in the literature has the advantage of correcting the aforementioned unrealistic result.