Calculation methods to evaluate the strength of tension lap splices are based primarily on nonlinear regression analysis of test results. While the results from these analyses are extremely useful, applicability of their results beyond the domain of the data is often, questioned. The objective of this research was to develop an expression for the calculation of bond strength based on a physical model of tension cracking of concrete in the lap-spliced region. Two different types of failure modes are considered: horizontal splitting that develops at the level of the bars (side-splitting failure), and vertical splitting that develops along the bar on the face cover (face-splitting failure). The developed expression was verified using results from 203 unconfined and 278 confined beam tests where the splice region was subjected to constant moment.