ANALYTICAL MODELS FOR FRP CONFINED CIRCULAR CONCRETE COLUMNS

Jacketing a reinforced concrete column by Fibre Reinforced Polymer (FRP) wraps primarily improves column performance, not because the jacket itself carries some fraction of the axial load applied to the column, but rather because, it provides lateral confining pressure to the column. This confining pressure places the concrete in a triaxial state of stress, altering the load-deformation characteristics of concrete. But contribution of wraps in improving the load carrying capacity of columns still remains controversial and there is need to develop suitable confining models for FRP wraps.Simple analytical equations based on confinement model developed by Richart et al. with modified value of confinement effectiveness co- efficient were proposed to predict the axial load carrying capacity of FRP confined circular columns under axial loading. The proposed equations were validated through the previous experimental database available in literature. A good correlation is obtained between the proposed equations and the existing experimental results. The confined concrete strength from tests was compared with the results from the developed empirical equations and the comparisons are favorable.