Steel bar for concrete reinforcement having a non-circular cross-section

A steel bar for concrete reinforcement, having a noncircular cross section and including a core portion, and having a longitudinally extending axis, which comprises:

• two sets of transverse ribs disposed respectively upon first diametrically opposite surface portions of the core of the steel bar, each set consisting of a number of transverse ribs of a lug-forming projection type disposed at a position corresponding to every pre-selected pitch in the longitudinal direction of the steel bar and extending therefrom in planes substantially transverse to the core;
• a pair of longitudinal ribs disposed on second diametrically opposite surface portions of the core at the intermediate positions between said sets of transverse ribs and extending from the core linearly in the longitudinal direction thereof;
• the outer portion of each of said longitudinal ribs being disposed upon a locus which is located a distance from the axis of said steel bar which lies in a range which extends between being equal to or less than the distance between said axis and the outer circumferential surface portions of said first diametrically opposite surface portions of the core located at the remotest position from said axis;
• the major central portion of the outer surface of each of said transverse ribs being disposed upon a locus having a larger diameter than the locus having the axis of the steel bar as its center and a surface which tangentially contacts the outer surface of said core;
• and
• the outer surface of the wing portion of each of said transverse ribs being disposed in such a manner that the distance from the axis is reduced progressively towards the outer portion of said longitudinal ribs;
• whereby said transverse ribs can mate with a female helical thread of a corresponding pitch in a nut, coupler or anchor sleeve.