Non-linear damping of FRP-confined damaged reinforced concrete columns

Despite the dynamic property of FRP-confined damaged RC (FRP-C DRC) columns are gaining attention, no non-linear material damping of FRP-C DRC has hitherto been evaluated. In this paper, the hysteretic behavior of two tested FRP-C DRC circular columns was first simulated by the confinement model of FRP-C DRC. Through analyzing the energy dissipation of the FRP-C DRC circular columns under cyclic loading with the validated model, a six parameter stress-dependent damping model for FRP-C DRC circular columns was proposed. Based on the proposed damping model, the non-linear material damping and dynamic response of the FRP-C DRC circular columns were evaluated by an iterative numerical method. The calculated results show that when the columns vibrate at resonance, the loss factor of the FRP-C DRC circular columns increases with an increase of the columns' initial damage, and the increase of their non-linear damping effectively reduces the dynamic response of the FRP-C DRC circular columns.