External bonding of circumferential fibre reinforced polymer (FRP) is a widely accepted technique to strengthen concrete structural component over the past decades. It is shown that FRP wraps increase the strength and deformability of structural components. Extensive studies have been performed on short RC columns with or without longitudinal rebar possessing length to diameter ratio less than three under concentric axial load to evaluate FRP effectiveness in these important structural elements. However, it should be noted that most of the practical RC columns have length to diameter ratio larger than three and are subjected to eccentric loading. Therefore, slenderness and axial load eccentricity are two decisive parameters which their effects on RC columns must be investigated.Increase in slenderness and/or axial load eccentricity decreases the effectiveness of FRPconfinement on improving strength and ductility of RC columns. Thus, it is crucial to specify aslenderness limit for FRP confined RC columns that ensure FRP wraps would be activatedefficiently like how they work for short columns. This paper investigates the effects of slenderness and eccentricity of axial load on the strength of FRP confined RC columns and a relation for calculating slenderness limit of FRP wrapped circular RC columns is proposed based on numerical evaluations.

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