High dynamic strength reinforcing bar splice and method of making

Abstract

A high dynamic strength or fatigue resistance is achieved in a taper thread reinforcing bar splice for use in steel reinforced concrete by coordinating the elongations of the coupler sleeve and bar to achieve the required movements of the coupler sleeve at the mouth. This is accomplished in the preferred embodiment by two attenuation grooves on the outside of a circular cylindrical coupler body at each end, each groove being placed in a particular axial relationship with respect to the end of the coupler sleeve and the area of thread engagement with the bar. The grooves are of different depths, with the groove closest to the mouth of the coupler sleeve being the deepest. Also the diameter of the circular cylindrical coupler body at each end is selected so that the wall thickness at the mouth is as thin as possible. At the center of the coupler sleeve there is an enlarged portion extending axially several threads beyond the last thread of each bar joined. The enlarged portion may be circular or hexagonal in exterior configuration. A lead chamfer which forms the innermost side wall of the attenuation grooves closest to the center of the coupler sleeve is desired to avoid excessive stress concentration at the side of these grooves. For such improved fatigue or dynamic performance of the splice, and efficient static performance, it is preferred to employ rolled bar thread in the splice system.