FRP confined hollow concrete columns under axial compression: A comparative assessment

Abstract An analytical model is developed for fiber-reinforced polymer (FRP) confined hollow circular concrete columns subjected to axial compression to study the effect of cohesive stiffness on confining pressure. The results are corroborated using 3D finite element (FE) analysis. The FE model is used to study the effect of confining stiffness on the strength and mode of failure in hollow columns. For low confining pressures, quasi-brittle failure occurs due to shear banding in the concrete; whereas for confining pressures in excess of a threshold, the response is ductile. Strength and size effect in hollow columns are compared with solid columns with the same outer diameter, FRP thickness and material properties. It is seen that hollow columns have reduced strength and are more susceptible to a size effect than solid columns.