JPH02190552A - High-strength shear reinforcement - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to shear reinforcing bars for reinforcing reinforced concrete columns and beam members, and particularly to high tensile strength and high strength shear reinforcing bars.

[Prior Art] In order to reinforce reinforced concrete columns and beam members, shear reinforcing bars are placed in the concrete to be cast, as shown in FIG. In the figure, IO is the main reinforcement, 11 is the shear reinforcement, and 12 is the poured concrete.

While the main reinforcement lO is placed parallel to the column and beam axes,
The shear reinforcing bars 11 are for reinforcing in the direction perpendicular to this, and usually have a length of 30 mm depending on the size, location, load, etc. of the columns and beams.
0 to 1000 m square hoops are arranged at appropriate intervals to surround the main reinforcement IO.

In addition, what is shown in the above-mentioned FIG. 3 is a hoop formed by processing an ordinary reinforcing bar into a single round rectangular ring and welding both ends.

On the other hand, a wire having a shape as shown in FIG. 2 is also used, and its material is iron wire or high tensile strength wire. Here, the description will be made assuming that high tensile strength wire is used.

(a) What is shown in the figure is what is called a high tensile strength welding hoop, and is a high tensile strength steel wire material I3 obtained by controlled cooling treatment immediately after hot rolling, or by quenching and tempering the wire material.
The ring is processed into a rectangular ring, and both ends are welded to form a hoop as shown at 14.

Moreover, what is shown in Figure (0) is a hot-rolled wire rod that is quenched and tempered to give it a predetermined high tensile strength and ductility, and then processed into a rectangular spiral.

[Problem to be solved by the invention] The shear reinforcing bars explained above in FIG. 3 have low strength.

Therefore, if the necessary strength is required, a large amount of material must be used and a large number of man-hours are required, and it will not be useful for making buildings taller and lighter in the future. Furthermore, the productivity of hoop processing by welding is low and the cost is relatively high.

Since the material of the shear reinforcing bars explained in Figure 2 (a) above is made of high-tensile steel wire rods, the strength and elongation of the welded parts are lower than that of the material itself, and this deficiency must be compensated for by various methods. However, the processing cost of the welding hoop is also high.

Furthermore, with the shear reinforcement explained in Fig. 2 (c), it is easy to form a spiral hoop, but the restraining force as a shear reinforcement is weak, so an extra number of rings is required, and the vertical component of the spiral is It does not contribute to reinforcement, and when considering the above points, the material cost becomes relatively high. Moreover, the workability is poor because twisting occurs as the spiral expands and contracts.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above-mentioned problems, and the present invention has been made to solve the above-mentioned problems. It is given the specified mechanical properties in the range of 60 to 14 θkgf/m2 and elongation of 6 to 15%, and is constructed so that the specified breaking strength can be obtained by winding this wire in an angular shape with three or more rings. .

Here, the basis for the above-mentioned mechanical properties of the steel wire rod used in the rolled-up shear reinforcing bars is shown below.

Some high-strength shear reinforcing bars with a tensile strength of less than 70 kgf/mm2 have already been tried, as shown in Figure 2 (a), and in the future, it is expected that structures with even higher strength will be used to make concrete buildings taller and lighter. The economic effect is extremely large.

On the other hand, if the welding strength exceeds 150 kgf/m+a2, welding generally deteriorates significantly, and if the shear reinforcing bars and main reinforcing bars are welded as necessary or due to a work error, the desired performance cannot be obtained.

2) The reason why the yield strength is specified as 60 to 140 kgf/■kaku2 is because in the case of weldable high tensile strength steel, the yield ratio is usually 0.85.
It is in the range of ~0.93, and as above, below Hkgf/l-2, the effect of increasing height and weight reduction is small, and 140kgf/l-2 or less.
At mm2 or more, in addition to welding deterioration, elongation decreases,
It is easy to lack restraint.

3) The elongation is set at 5 to 15% because when excessive force is applied to columns and beams due to earthquakes, etc., if the elongation is less than 5%, the concrete will break and scatter, but if it is more than 5%, it will only crack and break. It doesn't meet. Strength and ductility are also incorporated into the design to prevent damage.

5 to 10 for high-strength shear reinforcement bars that are being tested recently.
% is designed.

The larger the elongation, the better the ductility and toughness of the member, but elongation of 15% or more is difficult to manufacture with practical steel materials, and the yield strength of the member is
I don't really need it.

In this case, both ends of the wire of the reinforcing bar structure are not joined by welding, but are substantially joined by bending to form a hoop shape. If there are many turns, bind and bind with iron wire at key points of the hoop. You may.

FIG. 1(A) shows an embodiment of the present invention. In the present invention, a wire rod with a cross-sectional area of 173 or less of the cross-sectional area of a steel wire rod or steel bar, which is normally used as a shear reinforcing bar, is used, and the wire rod is heat-treated, preferably controlled cooling immediately after hot rolling, so that the tensile cuff is 0 to 0. 150kgf/+++w+2, yield strength. . ~
140kgf/ma+・, stretched to 15 pieces. A steel wire rod 4 having a diameter of 10 m+a or less and having a predetermined mechanical property of a certain range is used, and is wound up into an angular shape of three or more rings to form a shear reinforcing bar 1. In the figure, reference numeral 2 indicates the end of the wire rod, and shows a state in which both ends 2 of the reinforcing bar 1 are attached to the outer periphery of the reinforcing bar 1 by bending near one corner. Further, 3 indicates a binding line, which shows a state in which the reinforcing bars 1 are bound.

In addition, although FIG. 1 (11) shows an enlarged cross section of the main reinforcing bar 1, its shape may be annular as shown in the figure, or it may be rolled up as shown in FIG. May be stacked.

[As explained above, the action shear reinforcing bar is usually in the form of a single ring or spiral shape with a diameter of 10 to 20 mm, but in the present invention, it is made by winding multiple wire rods of high strength and high ductility with a diameter of 1 h or less. This significantly improves both performance and quality costs.

That is, by winding three or more rings, the breaking strength of the wire rod is proportional to the number of turns.

However, in the case of double winding, the strength of the bending connection at both ends of the wire is somewhat low. Furthermore, since no welding is used, there is naturally no deterioration in strength or ductility.

In addition, reinforcing bars are formed by winding wire rods with a small diameter, but using such a wire rod with a small diameter
This is for the following reasons. ■It must be a hoop with three or more turns. ■When adjusting the strength to a predetermined level during quenching and tempering of steel wires, the general characteristic that small-diameter wires have a large elongation can be used. ■Small diameter wire rods are easy to harden and therefore require less alloying elements.

[Example 0.13% G, 0.8% Sl, 1.2% Kn (all weight %), the balance consisting of Fe and inevitable impurities 5,
0■φ hot rolled steel wire is quenched and tempered to have a tensile strength of 1
After adjusting the yield strength to 84.4 kgf/m Peng2 and elongation to 1000%, the
It was rolled up, rolled up, and both ends were bent and wrapped around a hoop.

On the other hand, for comparison, as a conventional product, 13
．． 2+amφ wire rod, tensile strength 102 equivalent to above,
Okgf/ms” Yield strength 85kgf/ +mm
Quenched and tempered to 1'. In this case, the elongation is l! , 0%. Process this into a 700+u+ corner,
A hoop was formed by welding both ends of the wire at the sides.

When both of them were subjected to a tensile test as a square hoop, the breaking load of the reinforcing bars of the present invention was exactly 7 times that of the wire material, and the yield load was 1 to 2% lower than that of the wire material (and the average elongation was 13.5%). %Met.

On the other hand, as is well known, with conventional products, the strength of the wire material is 94 to 97% and the elongation is 4% in the welded area.
7%, which is considerably lower than 11% for raw wire material.

As a general property of coloring, quenching, and tempering, it was explained that the thinner the wire, the greater the elongation at the same strength, and the above results also show this.

[Effects of invention According to the present invention, there are the following effects.

■By making a hoop by winding heat-treated wire rods with standard strength and ductility, the same mechanical properties can be obtained for all wires, and there is no deterioration in strength or ductility as with a single-ring welded hoop.

■As with square spiral shear reinforcement bars, the lack of concrete restraining force is compensated for by increasing the spiral pitch, and there is no waste due to the vertical component of the spiral, and steel wire rods are fully utilized.

■Since it is a simple winding hoop, the process from wire rod to hoop can be made using a simple winding machine or bending machine, and it can be easily automated, and the production efficiency is extremely high, several times that of a welded hoop. It becomes productivity.

Rectangular spiral shear reinforcing bars may have high productivity at first glance, but after square winding to a predetermined pitch, compression and bundling steps are essential to increase transportation efficiency.

■The shear reinforcing bars of the present invention have extremely high field workability. On the other hand, rectangular spiral shear reinforcing bars are heavy because they are made up of a large number of reinforcing bars, and their springiness may be a hindrance to work.

Further, although various welded hoops do not have the above-mentioned disadvantages, when hoops are manufactured at a construction site, variations in quality due to welding become a problem.

■As a general property of heat-treated materials, the smaller the wire diameter, the greater the ductility at the same strength. This is extremely advantageous as a shear reinforcing bar as in the present invention.

■The smaller the wire diameter, the easier it is to harden, and the less alloying elements are required.

As explained above, according to the present invention, high-performance, high-quality, and homogeneous shear reinforcing bars can be supplied at an extremely low cost.

[Brief explanation of the drawing]

FIG. 1(a) shows an embodiment of the present invention, and FIG. 1(b) and (c) show a partial cross section. Figure 2 (A) shows a shear reinforcement using a welded hoop of reinforcing steel or high tensile strength wire, and Figure 2 (B) shows a helical rectangular shear reinforcement. Figure 3 shows the arrangement of reinforcing bars in reinforced concrete. 1... Overlapping shear reinforcing bar, 2... Cotton material end, 3
... Bind wire, 4... High tensile strength wire. (B) (B) υ\)

Claims (1)

[Claims] (1) Three or more rings of steel wire with a diameter of 10 mm or less and having predetermined properties in the range of tensile strength of 70 to 150 kgf/mm^2, yield strength of 60 to 140 kgf/mm^2, and elongation of 5 to 15% are wound into a rectangular shape. . A high-strength shear reinforcing bar characterized in that both ends of the wire rod are substantially joined to the ring by bending without welding to form a single hoop shape.