NFEA modeling of RC beams having exposed longitudinal reinforcement: Effects of debonding on shear behavior

This study presents a new and simple FE approach for modeling a beam with exposed longitudinal reinforcement that could provide a lower bound assessment of the impact of bond loss. The proposed element formulation considers the exposed bar as an embedded truss element. The elongation of the exposed steel is computed from the relative movement of the end points of the exposed steel. This element assumes that the anchorage of longitudinal reinforcement is sufficient to prevent an anchorage failure and uses a simple relationship to account for the effect of end bar slippage. The effect of non-failure inducing slippage is included to better model the overall response of the beam. The effects of loss of bond on member performance are examined, which provided detailed information on predicted energy dissipation capacity, ductility, and modes of failure of beams with unbonded regions. A comparison study is added to the document that presents a comparison of the predicted behavior of members with bonded and exposed reinforcement.;This study also presents a consistent beam-column element that provides a description of shear response. The element formulation is derived based on a two-dimensional micro-plane approach, where the material state of stress is defined by a two-dimensional state of strain. The advantages of the proposed model over other methods are demonstrated such as in predicting the change in shear stiffness. Unlike with other micro-plane models, the proposed model utilizes equilibrium to determine the sectional shear stress distributions that become irregular after cracking and due to other strength degradation effects. This approach enabled the proposal model to provide a more complete description of the shear stress distribution over the depth of the cross section over the entire loading history. Validation of this method is made against experimental test data of shear critical reinforced concrete beams both with and without shear reinforcement.