Using FEM to achieve acceptance criteria in FEMA performance levels for FRP-wrapped RC circular columns

Using fiber reinforced Polymer composite materials (FRP) in the rehabilitation schemes of vulnerable structural members is becoming more popular over the past decades. From the analytical point of view, the lack of numerical acceptance criteria in attaining the desired performance goal is a major restriction in employing this retrofitting method. The major parameter to control the seismic performance of frame members in nonlinear behavior is plastic hinge rotation angle (PHRA) especially for deformationcontrolled actions. To predict accurate performance of RC columns, strengthened with externallybonded FRP, there is an urgent need to discover PHRA as the acceptance criteria in a nonlinear static procedure stipulated in ASCE/SEI 4113 standard. As indicated, the parameters such as FRP thickness to section diameter ratio (aspect ratio), the relative height of FRP and the FRP material properties have significant influence on the behavior of the members strengthened with FRP under combineed cyclic axialflexural loading. For easy to use, analytical formulation is calibrated to evaluate PHRA as the function of the aforementioned triple parameters. An attempt has been made to simulate the RC columns with FRP laminate with generalpurpose finite element software ABAQUS. Verification of the numerical method has been done by comparing numerical results versus existing experimental tests.