Mesoscale Model for FRP-Confined Concrete

Abstract

The paper attempts to understand the macroresponse of fiber-reinforced polymer (FRP) confined concrete in terms of mesolevel interactions. Cylindrical specimens are modeled using a three-dimensional (3D) discrete-element formulation that uses polyhedrons of required geometry to closely approximate the actual shape and size of coarse aggregates. A coupled discrete-continuum approach is adopted to account for damage at length scales smaller than the smallest particle modeled. Constitutive models that capture aspects of mesobehavior crucial to confined concrete are developed, and mesoscale features affecting interface cracking, slip, and mortar damage are investigated. Increased confinement is seen to lead to some reduction in Mode I cracking and a marginal increase in Mode II cracking at the interfaces. However, the principal mechanism for strength gain is seen to be the prevention of localization and dispersal of slip. Increase in confining stiffness also results in increased mortar damage, which limits strength gain due to confinement, as well as a remarkable reversal of the platen effect.