US2606439A - Twisted reinforcing bar - Google Patents

Description

Aug. 12, 1952 F. sosNA 2,606,439

TWISTED REINFORCING BAR Filed July 29, 1947 [mimicr- FER xA/AND SOS/VA Patented Aug. 12, 1952 UNITED STATES PATENT OFFICE TWISTED REINFORCING BAR Ferdynand Sosna, Pruchna, near Cieszyn, Poland Application July 29, 1947, Serial No. 764,367 In Poland May 15, 1939 1 Claim. 1

Steel reinforcing members of high tensile stresses for reinforced concrete structures ought to satisfy the theoretical and practical conditions of the reinforced concrete architecture. When using steels of high tensile stresses and of high yield point for reinforced concrete structures, one tries to conserve the number of the bars of the structural part in question, and rather to diminish the cross sections of these bars. For increasing the tenacity of such bars of small cross-sections with respect to the concrete, the circular crosssections of the bars are often replaced by starshaped, square, double-circular or other crosssections of the members, but on condition that the circumferences of the smaller cross-sections of high strength ought to be as large or larger than the circumferences of the normal circular crosssections of the bars replaced by the above-mentioned bar-cross sections. For obtaining a sufficient tenacity of such bars, ordinarily transverse ribs or comb-shaped protrusions of the members, straight or screw-shaped, are used. The production of such bars with transversal ribs, combshaped or other protrusions, by rolling them, is difiicult and expensive, and for this reason the use of steel reinforcing members of very high stressesin spite of the obtainable technical and economical profits-is limited also by the difficulty to get a sufficiently large area of contact between the reinforcing members and the concrete, for assuring a sufficient tenacity between them.

The invention relates to an improved reinforcing member for reinforced concrete structure, and has for its object the production of such reinforcing bars, consisting of high value steel of high yield point, which are easy to be manufactured by rolling, a big and steady amount of tenacity with respect to the concrete being without difficulty obtainable.

On the accompanying drawing is shown by way of example, in Fig. 1 the construction of the crosssection of the member; in Fig. 2 the technical cross-section of the reinforcing member; in Fig. 3 a side-view of it; and in Fig. 4 a plan of the forces acting in the twisted bar under structural load.

According to the invention the cross-section of the said member is formed by geometrical division of a circular area into two halves of equal areas, the circumferences of which are combined by arcs, the radiuses r of which are equal to the half of the radius R of the main circle, and the circumference (21r7+1rR:21rR) of each half is equal to the circumference of the main circle. Such a cross-section enables the use of steels of double tensile stresses, when compared with the normal steels for reinforcing members having a breaking stress of KT=35-48 kg./cm

The technical shape of such cross-section is obtained by partly cutting away and rounding 2 the sharp protrusion a of the cross-section (Fig. 2). Such a cross-section, when straightened, is similar to the shape of a falling water drop.

For obtaining the necessary tenacity of the member with respect to the concrete, all members are twisted in such a way, that the axis V of the windings is not identical with the axis of the centre of gravity S of the cross-section of the bar (Fig. 2), so forming a screw of big taper. By twisting, for instance, the reinforcing members around the axis V corresponding to the centre of the main circle (radius B, Fig. 2), and not around the axis of the centre of gravity S of the crosssection, all misconceptions of the up to date constructions of high yield point steel reinforcing members are avoided. The tensile force P (Fig. 4), acting along the twisted member, has two component forces: (1) the force P1 along the twists, and the force N across the P1, as shown in the parallelogram of forces (Fig. 4). It is obvious, that the cross-force N assures steadily a sufiicient tenacity of the steel member with respect to the surrounding concrete.

I claim:

A reinforcing member for reinforced concrete 1 structures made of high value steel of high yield point, having a cross section in the form of a main semi-circle having a first small semi-circle of a diameter equal to the radius of the main semicircle with its fiat side coinciding with the flat side of the main semi-circle and its center lying between the center and one side ofthe main semicircle removed, and having a second small semicircle of a size equal to that of the first small semi-circle and with its flat side coinciding with the fiat side of the main semi-circle and its center lying between the center and the other side of the main semi-circle added, and having the sharp outer portion of the main semi-circle adjacent the portion from which the first small semi-circle was removed, rounded off, said reinforcing memher being twisted about a longitudinal axis substantially coinciding with the center of the main semi-circle.

FERDYNAND SOSNA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,123,239 Grifiel July 12, 1938 2,317,454 Greulich Apr. 27, 1943 FOREIGN PATENTS Number Country Date 523,089 Great Britain 1940

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