Stress–strain model and design guidelines for CFRP‐confined circular reinforced concrete columns

An analytical model is introduced in this paper to predict the stress–strain behavior of axially loaded circular reinforced concrete (RC) columns with internal longitudinal reinforcement and lateral ties confined by carbon fiber‐reinforced polymer (CFRP) composites. The proposed model is a two stage stress strain curve, with a second‐order polynomial in the first stage and a liner relationship with a reduced slope in the second stage. The model is an extension of the confinement model introduced by Richart et al. for confinement concrete. The model is based on the general mechanism of confinement, compatibility and equilibrium equations, and failure criteria of CFRP composites. The main parameters considered are the CFRP volumetric ratio ( ), column size, and concrete compressive strength ( ). The results predicted by the model were in good agreement with the results of current investigation and other proposed models of CFRP‐confined circular RC columns reported in the literature. In addition, based on the investigation results, new design guidelines were developed that can be effectively used to determine the ultimate confined axial stresses of a RC column. POLYM. COMPOS., 39:2722–2733, 2018. © 2016 Society of Plastics Engineers