Assessment of Reinforcement Steel-Concrete Interface Contact in Pullout and Beam Bending Tests Using Test-Fitted Cohesive Zone Parameters

Modeling the steel-concrete interface is a constant research topic in structural engineering. Several studies have explored advanced modeling methods, including cohesive models. This article fits into this context by investigating the bond strength at the steel-concrete interface based on a cohesive model. The numerical parameters considered in the software ABAQUS 2019 are investigated. The experimental and numerical results of pullout and beam tests were used as references for the parameters fitting process. With the Concrete Damaged Plasticity model (CDP), the physical non-linearity of the concrete was considered. The contact was described as a surface-to-surface interaction. The pullout tests' cohesive parameters were fitted with experimental tests. Regarding the beam models, an analysis was carried out verifying the use of pullout fitting parameters in the beam models, aiming to compensate for the eventual absence of these data. For the pullout models, the cohesive parameters fitting process yielded better results than those obtained with the recommended values. Improvements were especially significant regarding slippage at the maximum pullout force. The use of pullout test-fitted parameters in the beam models had a smaller influence on the ultimate load predictions. However, the slippage predictions and beam deflection were more affected by the change in cohesive parameters. The bond modeling using a surface-based technique performed well at a low computational cost, considering the materials' physical nonlinearities and 3D geometries. The results, also in general, did not significantly change the load predictions, which indicates a possibility of use in numerical simulations when the pullout data is available.