Experimental Research On Mechanical Anchorage Capability Of HRB500 Steel Bar

The mechanical anchorage of steel bars is a new anchorage measure which can increase the anchorage strength and reduce the development length efficiently. These are useful for the popularization and application of high strength steel reinforcements such as HRB500 steel bars and savings of steel reinforcements in engineering.In this paper, a pull-out test of HRB500 steel bars with mechanical anchorage measure have been carried out, and the mechanical capability is discussed, that is useful to solve the problem on the mechanical anchorage design of HRB500 steel bar in concrete structures.Based on the pull-out test results of 2 groups (72 specimens) of HRB500 steel bars with two measures of mechanical anchorage which are jointing with symmetric short re-bars and with anchor plate in end of the bars, the main factors that affect the bond-anchorage strength such as the strength of concrete, the development length of bars, the diameter of bars, the cover thickness of concrete and the transverse steel ratio are analyzed. The test results show that the bond-anchorage strength can be improved, and the development length of bars can be decreased with the mechanical anchorage measure in engineering.The empirical formulas for bond-anchorage strength and the bond-anchorageτ-s constitutive relationships for HRB500 steel bar with the mechanical anchorage measure are suggested, and a design suggestion of development length that have a certain reliability is proposed, these may be as a reference for future revision of the Chinese Design Code.