Behavior of heated damaged reinforced concrete beam-column joints strengthened with FRP

Abstract

This paper presents the efficiency of the external fiber reinforced polymer (FRP) composites in rescue the structural performance and controlling the mode of failure of the heated damaged reinforced concrete (RC) beam-column joint by nonlinear finite element analysis (NLFEA). Firstly, the RC beam-column model was validated against the published experimental results and then was expanded to consider the effect of column axial load level (0%, 25 %, 50 %, and 75 %) and elevated temperature (23 °C, 200 °C, 400 °C, and 600 °C) on the models with and without FRP composites. The structural performance was evaluated in terms of failure mode, stress distribution, pulling and pushing ultimate load capacity and corresponding displacement, horizontal load-displacement hysteretic loops, horizontal load-displacement envelopes, displacement ductility, energy dissipation, and stiffness degradation. The NLFEA results showed that the FRP strengthening technique of heated damaged RC beam-column joint with FRP composite enhanced the cyclic performance (higher load capacity, larger horizontal displacement, higher displacement ductility, higher energy dissipation, and slower secant stiffness degradation) and the efficiency of FRP composite increased with the heated damage level. Also, the FRP composite strengthening technique gave the ability to transform the joint-column regions mode of failure from brittle into a ductile mode of failure through the formation of plastic hinge in the beam only at a higher level column axial loads of more than 25 %. While the application level of column axial loads less than 25 % only enhanced just the ultimate axial load capacity and corresponding deflection.