Reinforced Concrete Frame Element with Bond Interfaces. II: State Determinations and Numerical Validation

Abstract

This is the second of two papers discussing the theories and applications of three reinforced concrete (RC) frame elements with bond slip between the reinforcing bars and the concrete. This paper presents the element state determinations for the displacement-based, the force-based, and the Hellinger–Reissner mixed formulations. The convergence, accuracy, and computational times of the three elements are compared through two numerical examples. The distinctive element characteristics in terms of force and deformation discontinuities between adjacent elements are discussed for the three proposed formulations. The ability of these formulations to detect the overall softening response of RC members due to the pullout failure of the rebars in the anchorage zone is also tested. The elements are all able to capture the drop in member stiffness due to the rebar slip and the failure due to bar pullout. The force-based and the mixed elements are, however, much more precise than the displacement-based element. The force-based element is slightly more precise, but the mixed element is numerically more stable.