Model Parameter Estimation for Hysteretic Behavior Simulation of FRP-Jacketed Reinforced Concrete Columns

Abstract

Fiber-reinforced polymer (FRP) composite jackets have been widely used to retrofit reinforced concrete (RC) columns within structural systems. This study proposes a lumped plasticity model to simulate the nonlinear load-deformation response of FRP-jacketed RC columns under seismic loading. An experimental database of 98 FRP-jacketed RC columns was assembled, including those with partial- or full-height jackets, circular or rectangular cross-sections, continuous or lap-spliced longitudinal reinforcement, and various FRP materials. The database is used to calibrate parameters of the hysteretic material model. Regression analysis was conducted to develop model predictive equations. Each predictive equation was established using leave-one-out cross-validation from 10 candidate design variables. Among the candidate FRP-related design variables, the FRP quantitative ratio and its ultimate strength were selected for inclusion in the empirical model parameter equations. The proposed model demonstrates better accuracy than the existing model in reproducing experimental load-deformation responses. Finally, the proposed model was applied to an FRP-retrofitted RC building frame with lap-spliced rebars to examine the seismic performance of the FRP retrofit compared with existing approaches. Overall, the proposed lumped plasticity approach for FRP-jacketed RC columns offers improved versatility, accommodating a broad spectrum of column geometries, and computational efficiency with reasonable accuracy in predicting load-deformation response.