The paper addresses the problem of modeling the bond between reinforcement and concrete as one of the key factors governing the deformational behavior of reinforced concrete structures, particularly in the analysis of loop joints, whose compliance is largely determined by the properties of the reinforcement anchorage zone. It is shown that existing code-based and empirical bond models are generally based on prescribed bond stress–slip diagrams and do not explicitly account for the direct influence of the level of normal stresses in the reinforcement, which limits their applicability in the numerical modeling of joints.The objective of this study is to develop an analytical bond law for reinforcement–concrete interaction that establishes a functional relationship between bond shear stresses, relative slip of the reinforcement, and normal stresses in the reinforcement. The proposed approach makes it possible to construct physically substantiated bond–slip diagrams over theentire range of reinforcement behavior during pull-out.The proposed model is based on the established relationship between average bond shear stresses and normal stresses in the reinforcement. At the initial stage of behavior, a linear relationship between bond shear stresses and normal stresses in the reinforcement is used to describe the stress–strain state. In addition, the ultimate stage of behavior associated with reinforcement slip in concrete is considered in detail. Various options for defining bond–slip diagrams for relatively short and long bars anchored in concrete prisms are examined. Examples of constructing bond–slip diagrams for typical classes of concrete and reinforcement are presented, demonstrating the applicability of the proposed relationships in the finite element method, in particular within engineering analysis software packages. This issue requires further detailed investigation in futurestudies. The obtained results can be applied to the evaluation of the compliance of loop joints and to the improvement of methods for their analysis.Further research should be focused on the verification of the proposed bond–slip diagrams against experimental pull-out test data, as well as on the experimental validation of calculation methods for loop joints using the developed bond model.
Author Biographies
O. D. Hryshchenko, National University of Water and Environmental Engineering, Rivne
Post-graduate Student
D. V. Kochkarov, National University of Water and Environmental Engineering, Rivne
