Design of FRP confinement for square concrete columns

A procedure for the design of confining fibre-reinforced polymer (FRP) reinforcement in square concrete columns to enhance their seismic resistance is presented. In previous research, a method was developed for the design of confining steel in square reinforced concrete columns [Sheikh SA, Khoury SS. A performance-based approach for the design of confining steel in tied columns. ACI Struct J 1997;94(4):421–31]. Patterned on the same philosophy, the procedure presented here allows a designer to calculate the amount of confining FRP required for a certain ductility performance given the axial load on the column and the properties of the FRP. The required FRP content increases with an increase in ductility demand and an increase in the level of axial load applied. The procedure can be applied to new and existing square concrete columns and is corroborated with the experimental results obtained from realistically sized columns tested under simulated earthquake loads.