Generalized Axial Stress-Strain Response of Rectangular Columns Confined Using CFRP Jackets and Anchors

AbstractThe results of an experimental study of the cyclic axial stress-strain response of rectangular concrete columns confined with a combination carbon-fiber-reinforced polymer (CFRP) jacket and CFRP anchors are presented and discussed. The test variables include aspect ratio of the column section, area of CFRP wraps, and area and configuration of the CFRP anchors. It was found that adding CFRP anchors improves the confinement effectiveness of the CFRP jackets, leading to substantially enhanced envelope stress-strain response and ductility of axial failure. Furthermore, changing the anchor configuration while maintaining the total anchors’ cross-sectional area does not produce a noticeable effect on the envelope stress-strain curve. The cyclic part of the stress-strain response of the CFRP-anchored specimens is similar to that of the companion specimens confined with CFRP sheets without anchors. Based on the results of this study, analytical expressions are derived for predicting the stress-strain curve, taking into account the effect of CFRP anchors. The proposed model is able to predict the envelope and cyclic responses of concrete columns confined with CFRP sheets only and columns confined with a combination of CFRP sheets and anchors.