MA Lotfollahi-Yaghin - Associate Professor, Dept. of Civil Eng., University of Tabriz, Tabriz, Iran
M Ahmadi-Azar - M.S.C in structure engineering
A Rezaei - M.S.C in structure engineering

Wrapping RC columns using Fiber Reinforced Polymer (FRP) materials is one of the recent methods of strengthening, in RC columns. Most of the undertaken studies in the past were concentrated on studying FRP confined RC columns subjected to uniaxial loading, however, in practice; the column structures usually undergo combined axial loading and bending moment. This paper represents the results of numerical evaluation of retrofitted RC columns subjected to eccentric loading. Also an investigation on performance of different confinement models has been carried out and the results were compared with those existing experimental and analytical models in literature for validation of proposed analysis. In each case, the numerical model has been analyzed under axial loading and different eccentricities. Then, the set of bending moment-axial load interaction curves have been drawn. Investigation on the effect of composite over wrapping architecture such as lay up stacking sequences, number of composite plies and also column slenderness has been considered. According to the out coming results, using a symmetric lay up combined of longitudinal and transverse fiber directions, is more appropriate for confining a RC column subjected to a concentric and eccentric loading. Sufficient number of layers should be used to obtain well confinement. It is observed that FRP externally bonding is less effective in long columns than short ones.

Load eccentricity; RC columns; FRP composite; Confinement