US3312035A - Reinforcing bar - Google Patents

Description

April 4, 1967 E. J. VAN KOOT REINFORCING BAR Original Filed Jan. 19, 1961 IN VEN TOR E du ard Jean van Knot ATTYS.

Patented Apr. 4, 1967 3,312,035 REINFORCING BAR Eduard Jean van Koot, Doorwerth, Netherlands, assignor to Tor-Isteg Steel Corporation S.A.H.

Original application Jan. 19, 1961, Ser. No. 83,720, now Patent No. 3,123,941, dated Mar. 10, 1964. Divided and this application Dec. 19, 1963, Ser. No. 331,744

1 Claim. (Cl. 52737) This invention is a division of my application Ser. No. 83,720 filed on Jan. 19, 1961, now Patent No. 3,123,941.

This invention relates to a reinforcing bar, more particularly a reinforcing bar for use in concrete, which is provided on the surface of its preferably cylindrical bar core with a plurality of individual oblique lugs or short ribs which are inclined relatively to the bar axis and which, arranged individually in specific direction, have a uniform cross-section over substantially their entire length.

Many constructional forms of such reinforcing bars are known; in some cases these bars are also provided with longitudinal ribs, and in some cases no such longitudinal ribs are provided and then only oblique lugs or ribs are arranged on the bars.

The first-mentioned bars with longitudinal ribs in some cases exhibit less flexibility than smooth bars, and in fact this has been found to be due to the peak stresses occurring at the apices of the longitudinal ribs. If the longitudinal ribs are provided with sharp edges, the fatigue strength of the bar is also reduced.

If no longitudinal ribs are provided, and the bars only comprise oblique lugs or ribs all inclined in the same direction, there is a danger that when the bar embedded in concrete is subjected to stress it may rotate out of its bond, particularly if the bar was subjected to a qualityimprovement treatment by twisting. Bars are in fact already known in which this risk has been countered by arranging inclined lugs in various directions of inclination, namely, inclined in opposite directions to one another. But this results in the disadvantage that when such bars are twisted, some of the lugs are upset and others are stretched. Now, the upsetting or stretching of such lugs can lead to various disadvantageous effects depending on the quality of steel and on the kind of quality-improving treatment to be carried out, after-treatment, aging, etc., and may particularly result in rendering the bar brittle with peak stresses at the lug apices, and further undesirable effects.

It has already been recognized in connection with this that it is more advantageous to arrange the oblique lugs of a bar in the same direction of inclination throughout, so that when such a bar is twisted, either all the lugs are upset or all are stretched.

The invention relates to a reinforcing bar having a plurality of individually arranged oblique lugs or short ribs of substantially uniform cross-section, which are inclined relatively to the bar axis. It is characterized in that the individual oblique lugs are directed at different acute angles to the bar axis. Preferably, the oblique lugs can form with the bar axis angles in the range of between 20 and 80".

Bars are in fact already known in which short lugs are arranged between longitudinal ribs and deviate from a line parallel to the course of the longitudinal ribs first in one direction and then in the other.

In contrast, the invention is concerned with the arrangement on the bar periphery of only oblique lugs or short ribs which are arranged individually and which form different acute angles among themselves with the bar axis. The fact that longitudinal ribs are not provided facilitates the rolling of the steel and avoids the initially mentioned dangerous disadvantages which result from the provision of longitudinal ribs.

The invention can be put into effect in various Ways. For example, it is possible within the scope of the invention for the oblique lugs to be arranged in at least two groups which are not similar to one another, the lugs within each group being preferably parallel to one another, but extending at different angles to the bar axis from those formed by the other group or groups.

For the quality improvement of a bar according to the invention by cold working, this bar can be twisted either in the direction of inclination of the oblique lugs or in the direction opposite thereto. Which of these methods is to be preferred in each individual case depends more particularly on the kind of quality-improvement treatment and after-treatment of the bar, andas initially mentionedit must be borne in mind that the lugs are subjected to either an upsetting effect or a stretching effect during twisting.

In the accompanying drawing:

FIG. 1 is a side elevational view of a part of a reinforcing bar of cylindrical formation with the lugs on each side of the bar being parallel with each other and the lugs on one side of the bar being longer than the other side lugs and extending at more acute angles. to the longitudinal axis of the bar, and

FIG. 2 is a side elevational view of the other side of the reinforcing bar showing in full lines the longer lugs of one set.

As illustrated, the bar 1 is provided with dissimilar groups of lugs 4 and 5 respectively at opposite sides of the bar, FIG. 1 showing a group of oblique lugs 4 which are all inclined at 45", whereas the lugs 5 at the other side of the bar 1 as shown in FIG. 2 are of the same length and longer than the lugs 4 and are inclined at about 25 relative to the bar axis 6.

The broken lines a extending longitudinally of the bar 1 show that the transverse distance covered by each of the lugs 4 and 5 is the same in both groups, corresponding ends of the lugs at each side of the bar 1 terminating in a straight line as indicated by the broken lines a with the transverse distance covered by the lugs of each group being indicated at x at the right-hand end of FIG. 1.

The bar is locked against any possibility of rotating out of the concrete, without having to provide for this purpose the longitudinal ribs which are recognized to be inexpedient.

Of course, in addition to the form illustrated, many other possibilities may be resorted to in the production of this reinforcing bar. More particularly, any desired number of groups of oblique lugs can be provided with the lugs of each group being of the same length and contrasting with the length of the lugs of other groups, while the individual shape of the lugs, their spacing and their length can all be varied optionally within the framework of what is technically possible and the effects which are to be achieved.

What is claimed is:

A concrete reinforcing member comprising a longitudinal cylindrical bar; a first and second group of diametrically opposed relatively short oblique lugs on said bar, each of said lug groups comprising a plurality of spacedapart parallel lugs inclined relative to the longitudinal axis of said bar, the first group of lugs on -a first side of said bar all being inclined in a first direction, the second group of lugs on the other side of said. bar all being inclined in a direction opposite to said first direction, the two groups of said lugs being inclined at different angles of inclination relative to the longitudinal axis of said bar, said first group of lugs being disposed at a more acute angle relative to said longitudinal axis than is said second 3 4 group, said first group of lugs being longer than said sec- 1,152,606 9/ 1915 Collings 52-740 0nd group of lugs, the angle of inclination and length of 1,339,226 5/ 1920 Schuster 52-737 said lugs being so related that the transverse distance covered by each of said lugs is the same in both first REI N PATENTS and Second 2 p 6 223,396 7/1959 Australia. 204,346 11/ 1956 Australia. References Cited the Exfififil'lfil' France. UNITED STATES PATENTS 1,181,961 1/ 1959 France.

1,076,192 10/1913 Coryell 52736 1,151,947 8/1915 Havemeyer 52 74O 10 FRANK L. ABBOTT, Primary Examiner.

J. L. RIDGILL, Assistant Examiner.

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