PARAMETRIC ANALYSIS OF CFRP STRIPS INTERNALLY CONFINED RC COLUMNS

Fiber-reinforced polymer (FRP) sheets has been widely used as external confinement for retrofitting and strengthening structural elements as they increase axial, shear, and bending capacity. Despite many advantages, FRPs suffer from some drawbacks such as have weak durability against thermal and harsh environment. Thus, the use of FRP strips as internal confinement was proposed so that the concrete cover can protect the FRP strips. In this study, a three-dimensional (3D) nonlinear finite element (FE) model is developed using ABAQUS software to study the cyclic behavior of carbon fiber-reinforced polymer (CFRP) strips internally confined reinforced concrete (RC) columns. A validated model was used to conduct the parametric study to investigate the effect of FE model under different intensities of axial load (i.e. 70kN, 100kN, 200kN, 300kN, and 400kN) and distances between the CFRP spirals (100mm, 150mm, 200mm, and 250mm). Results indicate that an increase in the axial force has significantly increased the stress on the surface of concrete and can lead to the rupture of CFRP strips in the column. Meanwhile, increasing the distance between CFRP strips has increased the stress at the plastic hinge area and experienced buckling of longitudinal reinforcements at 250 mm of CFRP strips.