MODEL OF CONCRETE CONFINED BY FIBER COMPOSITES

Fiber-wrapping or encasement of concrete in fiber-reinforced plastic ( FRP) shells significantly enhances strength and ductility of concrete columns. However, design of such hybrid systems requires an accurate e stimate of the performance enhancement due to the confinement mechanis m. Current design procedures are simple extensions of the models devel oped for conventional reinforced concrete columns. Previous studies ha ve demonstrated that such models may not be conservative for FRP-encas ed concrete. A simple model is presented to predict the complete bilin ear stress-strain response of FRP-confined concrete in both axial and lateral directions. The model is based on correlation between the dila tion (expansion) rate of concrete and the hoop stiffness of the restra ining member. The parameters of the model are directly related to the material properties of the FRP shell and the concrete core. The predic ted stress-strain curves compare favorably with the results of the pre sent study, as well as tests by others on both fiber-wrapped and FRP-e ncased concrete columns.