Damage-Plasticity Model for FRP-Confined Normal-Strength and High-Strength Concrete

This paper presents a modified damage-plasticity model for fiber-reinforced polymer (FRP)-confined normal-strength and high-strength concrete (NSC and HSC). The proposed model is based on a concrete damage-plasticity model from the literature, which is improved through accurate incorporation of the effects of the confinement level, concrete strength, and nonlinear dilation behavior of FRP-confined concrete. The proposed model uses a new and accurate failure surface and flow rule that were established using a comprehensive and up-to-date experimental test database and it incorporates an analytical rupture strain model for the FRP jacket. Finite-element (FE) models incorporating the proposed damage-plasticity model are developed and validated for concretes having up to 110-MPa compressive strength confined by different types of FRP under a wide range of confining pressures. Comparisons with experimental results show that the model's predictions of (1) axial stress-axial strain, (2) lateral strain-axial strain, (3) axial stress-volumetric strain, (4) plastic volumetric strain-axial plastic strain, and (5) plastic dilation angle-axial plastic strain relations are in good agreement with the test results of FRP-confined NSC and HSC. The accurate predictions of the compressive strength and ultimate axial strain of FRP-confined concrete were achieved by establishing the hardening/softening rule and flow rule based on the level of confining pressure and modeling the failure surface of the confined concrete by incorporating the effect of unconfined concrete strength. (C) 2016 American Society of Civil Engineers.