FINITE ELEMENT ANALYSIS OF RC COLUMNS CONFINED WITH FRP SHEETS

Abstract

A nonlinear finite element model is developed using ANSYS for concrete subjected to uniaxial compressive loading and confined by fiber reinforced polymer (FRP) sheets. The column section may have either circular or square shape. The proposed FEA model has been validated with the experimental results from various researchers. A reasonable agreement has been found between FEA and experimental results. The behavior of small and large scale FRP wrapped concrete columns under uniaxial compression has been investigated using the developed model. The effect of the thickness, stiffness and fiber orientation of the FRP sheets as well as unconfined concrete strength on confinement effectiveness and stiffness of the strengthened columns has been evaluated using the present model. Finite element analysis results showed substantial increase in axial compressive strength and stiffness of FRP confined concrete columns compared to unconfined ones. The increase in wrap thickness and modulus of FRP sheets resulted in enhancement of axial strength and stiffness of the columns. The confinement effectiveness is found to be higher for lower grade of concrete. The analysis results suggest that zero degree fiber orientation of FRP is most effective for confinement under uniaxial loading. The present model can also effectively simulate the behavior of square column confined by FRP sheets. Based on the present analysis results stress distribution in concrete and FRP is obtained which helps in understanding the confinement mechanism of the columns.