Ultimate bond strength of plain round bars embedded in concrete subjected to uniform lateral tension

• The analytical solution of bond strength for plain round bars subjected to uniform lateral tension.
• The experimental study on bond behavior of plain round bars under equi-biaxial lateral tension.
• The sensitivity analysis for evaluating the effects of main factors on the ultimate bond strength of plain round bars.

The bond strength of plain round bars, which is important for the assessment of historical buildings, is greatly influenced by the lateral stress state. To predict the bond strength of plain round bars subjected to lateral tension, a few empirical models were presented based on test results. However, these models are probably restricted for application since the test parameters adopted in the experiment are limited. Therefore, an analytical study, which is independent of test parameters, is made in this paper to investigate the bond behavior of plain round bars embedded in concrete subjected to uniform lateral tension. Based on the theory of elasticity, an analytical solution for the ultimate bond strength is derived. When the shrinkage of concrete and the geometric and mechanical parameters of bars and concrete are provided, the analytical solution can be used to evaluate the ultimate bond strength of plain round bars subjected to uniform lateral tension. 72 pull-out specimens are made and tested to verify the analytical solution. The results show that, the analytical predictions are in good agreement with the experimental results. Finally, a sensitivity analysis is made to evaluate the effects of main factors on the ultimate bond strength of plain round bars, and a simplified model is provided for practical applications.