Nonuniform Bond Stress Distribution Model for Evaluation of Bar Development Length

To evaluate the development length of a reinforcing bar embedded in concrete, the bar with a full development length should be tested because the bond stress distribution is not uniform. In the present study, a design method was developed to estimate the full development length of a bar by using the result of a relatively simple pullout test for a short unit bar length. For this purpose, a nonuniform bond stress distribution model was proposed, from which a design equation for bar development length was derived. The proposed method was applied to 534 existing test specimens to predict the development length or the average bar bond stress. The prediction results were compared with the test results. The results showed that the accuracy of the proposed method was comparable to that of ACI 408R-03. Further, to demonstrate the applicability to new materials, the proposed model was applied to existing test specimens of high-strength self-consolidating concrete with reinforcing bars.