Slenderness Limit for Short FRP-Confined Circular RC Columns

Strengthening of RC columns through lateral confinement provided by external fiber-reinforced polymer (FRP) jackets (or wraps) has become an increasingly popular technique over the past decade. Nevertheless, relevant design provisions in existing design guidelines are only concerned with the design of FRP jackets for short columns in which the slenderness effect is negligible. Even for the safe application of the existing design provisions for short columns, there is an urgent need to define a slenderness limit for short FRP-confined columns. This paper proposes such a slenderness limit expression based on the numerical results of a comprehensive parametric study that investigates the effects of various parameters on the slenderness limit using a recently developed theoretical column model. An important feature of the proposed expression is that it separates the effect of FRP confinement on the slenderness limit from the effect of other parameters. This feature allows existing slenderness limit expressions for short RC columns of different forms to be readily upgraded for use in the design of FRP-confined RC columns by incorporating the part dealing with the effect of FRP confinement in the proposed expression.