Bond Failure of Deformed Reinforcing Bars Based on the Longitudinal Splitting Effect of the Bars

Abstract

The anchorage capacity of deformed reinforcing bars is restricted by one of the following failures: (1) bond slip failure where the bar is just pulled out and leaves the surrounding concrete without further damage, or (2) splitting failure where slipping between concrete and reinforcement causes splitting in concrete cover. In normal beams, with relatively thin concrete cover, the splitting failure is most common. Since splitting failure gives a much smaller anchorage capacity than bond slip failure does, it is very important to consider this failure. The test results indicate that the force developed along a deformed bar can be regarded as a straight line function of the length of the splitting lines in the section as well as of concrete tensile strength. Surrounding reinforcement has a great influence on the developed force depending on the amount of surrounding reinforcement area transversing the splitting surface. The influence of the shape of the bar surface deformations is studied by tests giving both types of failure. The deformation shape was varied with different diameter and different distances. Considering splitting failure, the distance between lugs had less importance than lug diameter. Both parameters studied are of less importance in case of splitting failure than in case of a pure bond slip failure. /Author/