Finite element simulation of bond-zone behavior of pullout test of reinforcement embedded in concrete using concrete damage-plasticity model 2 (CDPM2)

A finite element (FE) model is used to simulate bond-zone behavior in a pullout test of a single bar embedded in concrete. The proposed FE model treats both the concrete and reinforcing bar in the bond-zone with refined solid elements to explicitly represent the deformations of rebar and the surrounding concrete and employs the surface-to-surface contact model on the concrete-rebar interface to simulate proper load transfer. In modeling of pullout tests, the significance of using a concrete model that can accurately simulate nonlinear response under high confining pressures is emphasized. Two concrete models are discussed and compared from a constitutive modeling perspective: (1) concrete damaged-plasticity (CDP) model and (2) concrete damage plasticity model 2 (CDPM2). Three pullout tests are simulated via the proposed modeling approach each with two concrete models. It is shown that the FE model with CDPM2 produced bond stress and slip responses comparable to test data, while the FE model with CDP model overpredicted bond stress due to concrete response overestimated under high confining stress states. The FE models with CDPM2 can capture different failure modes for different types of specimens: splitting failure for the specimen without confinement and pullout failure for the specimen with confinement.