Abstract: An elongated tubular steel body has a longitudinally extending internal seat for engaging an end portion of at least one generally cylindrical concrete reinforcing bar or rebar having a center axis. A series of longitudinally spaced and peripherally spaced threaded holes are formed within the body in opposing relation to the seat, and a screw is threaded into each hole. The axes of the holes and screws define planes which converge toward the center axis of the reinforcing bar and are arranged in alternating staggered relation along the length of the body. The tubular body may have different cross-sectional shapes or profiles, and the seat may be formed by converging wedging surfaces or longitudinally extending circumferentially spaced rails each having teeth engaging the body and reinforcing bar.