Erico International Corporation

Geoffrey M Bowmer

John E Groth

Paulus W Gruson

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.

High dynamic strength reinforcing bar splice and method of making

A position coupler for connecting reinforcing bar in concrete construction where neither bar is able to rotate either conveniently or not at all includes a sleeve at least a portion of which is internally cylindrically threaded and which receives at least one split collar insert. The insert has external cylindrical threads which match the internal cylindrical threads of the sleeve and also has internal tapered threads which match the tapered external threads on the bars to be joined. The inserts, in addition to being longitudinally split are provided with either a transverse slot or a hex head on their outer ends to receive a wrench. When a transverse slot is provided a spanner wrench may be inserted between the bar and sleeve. The tightening of the insert creates a wedge action which hoop stresses the sleeve locking the parts together and reduces slippage. The insert may be locked anywhere along the interior of the cylindrical thread portion of the sleeve to connect bars at different axial spacings. In a preferred form the sleeve is machined from stock with the cylindrical threads receiving the insert being formed on one end while the opposite end is provided with a taper thread socket having taper threads which match the external tapered threads of the bars to be joined. In another embodiment the sleeve is formed of tube with the internal cylindrical threads extending the length of the sleeve and an insert for each bar is employed.

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Oisterwijk, Netherlands

Geoffrey M Bowmer