Design model for square RC columns under compression confined with CFRP

The enhancement of the mechanical behaviour of reinforced concrete (RC) columns with regard to axial compression is an up-to-date concern, namely if the strengthening of existing structures is to be considered. In view of this, external confinement with FRP systems has been tested in order to become a feasible technique, since it seems to have important advantages over other systems such as its high strength and stiffness in relation to weight and its improvement of strength and ductility while confining RC columns. Square columns confined with FRP show a more complex interpretation of their behaviour, when compared to circular columns. Accordingly, the present work includes the analysis of two experimental programs regarding axial compression on CFRP confined RC columns: one on circular and square specimens with different corner radii; the other on square specimens with side lengths ranging from medium to large. Based on this, modelling equations are proposed to predict maximum axial load, axial strain and lateral strain, as well as the entire behaviour until failure with curves of axial load-axial strain and axial load-lateral strain. The modelling results show that the analytical curves are in general agreement with the presented experimental curves for a wide range of dimensions. (C) 2013 Elsevier Ltd. All rights reserved.