JPS6025589B2 - How to arrange threaded reinforcing bars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for arranging spiral reinforcing bars for reinforced concrete structures.

Reinforced concrete columns and beam bars have axial reinforcements as the main reinforcements, hoop reinforcements or stirrup reinforcements (hereinafter referred to as sub-reinforcements) for reinforcing several breaks and restraining the concrete.

And those wealth in recent years. The use of spiral reinforcement bars has been proposed and has begun to be implemented. By the way, in the conventional manufacturing process for columns and beams in general reinforced concrete structures, main reinforcements are first fixed at positions that will become columns, and regular reinforcements are wound around the main reinforcements in a direction perpendicular to the main reinforcements and fixed at predetermined intervals.

The formwork is then assembled. Moving on to the part of the beam that connects to the column, in the case of the beam, first, the formwork is set up on paper, and the main reinforcing bars are inserted into it along with the sub-reinforcement, and the joint with the column is roughened, and then the beam is connected. The main reinforcement of the section and the Toyama reinforcement are fixed and the assembly of one layer is completed.

Concrete is placed in this state, and after curing is completed, the formwork is removed and the next level is moved on. As mentioned above, the diameter of the sub-reinforcements used in the sequentially constructed reinforced concrete structures is generally 9 sides or 13 sides, and the yield strength is also about 25 to 30 kg/k.

All structural design calculations are performed using this yield strength as a standard. The ends of the secondary reinforcement are fixed by wrapping them around the main reinforcement, bending them toward the center of the column or beam, and embedding them in the concrete. Therefore, when the main reinforcing bars and the concrete inside try to spread due to the rolling force, the reinforcing bars embedded in the concrete tend to come out. If this slippage occurs, it becomes impossible to restrain the force that is trying to spread due to the axial force. An improvement on this point is the method of using spiral reinforcing bars, which eliminates the need for fixing each roll. However, during construction, it has become difficult to wrap the spiral reinforcing bars while fixing them in a predetermined position, so various efforts have been made. One example is a method in which spiral reinforcing bars are formed into the required shape in a factory, delivered to the construction site, the main reinforcing bars are reinforced, only the rear spiral reinforcing bars are stretched like stretching a coil spring, and then fixed in place. There is. In this case, if the diameter is large, for example, if a spiral reinforcing bar with a pitch of 20mm is made from 13 round reinforcing bars for a column with a diameter of 70mm, the weight will be 44k9/piece, which is quite heavy and difficult to work with.

In addition, if a round reinforcing bar cage with a diameter (winding diameter) of 60 m or less is processed at a factory to a pitch of 20 m and compressed during transportation to reduce its volume and then tied up on site, residual deformation will occur. It will be done. In other words, if you make a basket with 60 enemies, 20
In order to avoid residual deformation when winding spiral reinforcing bars at a pitch, the yield strength should be 25.2k9/9 for a diameter of 9 skin.
A fence with a diameter of 13 mm requires more than 35.36 kg of material per square, and is it on the 500 side? Similarly, when making a basket, use 9.
Willow one is 34.8X9/gauge, 13 legs diameter is 50
If you are making a basket with a diameter of 9 k9/fence, 40 k9/0, it will deform unless it has a yield strength of 56 k9/fence with a diameter of 9 ribs, or 77 kg/ground with a diameter of 13 ribs. Also, even if you want to correct the deformed pitch, with a basket on the 500 side,
In the case of a diameter of 13 willows, a force of 43k9 is required, and even if correction could be made with a force of 43k9, the pitch would be partially deformed and accurate pitch correction would be impossible.

Furthermore, it is dangerous to perform pitch correction work on scaffolding in a high position. Therefore, as an example, a 3m spiral reinforcing bar for a column is heavy, so it is divided into pieces to reduce the weight of the work unit. They are also installing hanging equipment.

As described above, construction using conventional spiral reinforcing bars inevitably has many drawbacks such as poor workability, low work efficiency, and uneconomical performance.

This invention was developed in order to solve the problems of the previous song, and the invention will be explained below.As mentioned above, spiral reinforcing bars prevent buckling of reinforcing bars in the direction of gravity, and can be used to strengthen steel bars and strengthen concrete. Since the purpose is to provide restraint, if the diameter of the helical reinforcing bar is reduced to eliminate residual deformation due to compressive force, it is naturally necessary to increase the strength of the helical reinforcing bar.

For example, SS41 material on the 13 side is used for the spiral reinforcing bar for a 50-yard ship, and if you try to change it to the 7 side, which is easier to deform, the required yield strength is 24k9/Iso x Kamesakami = 82
-7k9/masu.

Also, if you try to replace the 9 side ◇ of the SS41 material for 50 enemies to the 6 side, the price will be 24k9/I hate X Gi Mikure = 539k9/Yen.

Note that the above-mentioned 24k9/fence is the allowable stress level for long-term stress specified in the Building Standard Law Enforcement Order.

In addition, the 132.7 fence indicates the 13 legs, the 38.5 rock has 7 legs, the 63.6 square indicates the 9th side◇, and the 28.3 square indicates the 6th side cross-sectional area. Therefore, in this invention, it can be manufactured reliably by the method described later, and the cross-sectional area of the conventional spiral reinforcing bar can be reduced to approximately 1/1.
2 or less, that is, the weight of the spiral reinforcing bar can be reduced by about half or less and the workability on site can be improved.

Note that spiral reinforcing bars are covered with concrete with a predetermined cover, but it is said that in the event of a fire, spiral reinforcing bars can be exposed to heat of approximately 40 pi If heated to a temperature higher than the above tempering temperature, the strength will decrease, so the yield strength is 160k.
When the yield strength is 9/m or more, the yield strength becomes 130 to 160 kg/shore due to the heat received during the fire, and it is preferably used within the above range.

Although the above description has been made regarding a square spiral reinforcing bar, the present invention can also be applied to any spiral reinforcing bar having a circular, rectangular or other shape.

The above spiral reinforcing bar arrangement method is explained using drawings.
No plastic deformation during elongation and yield strength of 130k
9/ After forming the helical reinforcing bars 1 by forming high-strength steel wires of rock or higher into a spiral shape with the required pitch and shape, the main reinforcing bars 2 of the columns are brought to the site in a fully compressed state as shown in Fig. 1. Next, the spiral reinforcing bar 1, which becomes the hoop bar, is stretched by itself, the pitch is adjusted, and it is tied to the main reinforcing bar 2 and locked.

Next, the beam main reinforcing bars 3 are inserted into the main beam reinforcing bars 3, and the helical reinforcing bars 1', which serve as stirrups, are similarly inserted into the beam main reinforcing bars 3, and the spiral reinforcing bars 1' extend and lock on their own in the same way as the columns. In addition, spiral reinforcing bars 1, 1
' may be an angular spiral as shown in FIGS. 1 to 4, or a circular spiral as shown in FIGS. 5 and 6.

Incidentally, there are cases where a head 4 is formed at the end of the spiral reinforcing bar 1 to ensure fixation. According to an experiment, when a helical reinforcing bar with a head 4 at the end was embedded in concrete with a compressive strength of 210 k9 / 15 mm and a pullout test was performed, the reinforcing bar without a head became a reinforcing bar with a embedding depth of 15 mm. Compared to 2. With the load of g sound,
Also, with 20 skins, the concrete cracked under four times the load. Therefore, it can withstand higher loads than reinforcing bars without heads.

Therefore, the head installed at the end of the spiral reinforcing bar is 200~
If you bend it at a position of 30 degrees and point it toward the center of the pillar, beam, etc., it will be securely fixed.

Note that the spiral reinforcing bars used in the present invention can also be manufactured, for example, by the following method.

That is, to explain according to FIG. 7, the coil-wound reinforcing bar 5 is continuously heated through a yield heating coil 6 and a cooling device 7, and then heated to the temperature of the heating chamber through a competitive heating coil 8, and then heated to a predetermined shape. The material is wound spirally around a winding machine 9 at a predetermined pitch and shaped, and is then cooled by air cooling or by using a cooling mechanism 10 to achieve a fully compressed state. This invention has the above-mentioned configuration, and since the spiral reinforcing bars are formed using high-strength steel wire with a yield strength of 130k9/iso or higher, the yield strength is 3 to 5 times higher than that of conventional reinforcing bars, and therefore Since the required weight is small and there is no plastic deformation during pitch adjustment, handling becomes easy and the effect is significant.

The following experiments were conducted to elucidate the mechanical properties of concrete structures using the spiral reinforcing bars of this invention. In other words, the influence of the yield strength of spiral reinforcing bars on the breaking strength of sardines was confirmed through experiments.

And yield strength 130k9/m...A, 60k9/m...
...B, 30k9/fence...C were tested for each of the reinforcing bar ratios, diameters, and pitches shown in the table below. As shown in Figure 8, the entire test was conducted with a total length of 330 mm and a/d = 1.5 (d: beam length, section span).

In this test, force was applied using hydraulic pressure and a jack via a load cell at the point indicated as P in the figure, and the load P and deformation 6 were recorded by an X-Y recorder. An example of this is shown in FIG. 9, in which the ultimate stress at the nada section is calculated from the maximum load of the P-6 curve (historical restoring force characteristics), and is illustrated in relation to the scale section reinforcement reinforcing bar ratio. Next, the stress generated in the helical reinforcing bars during the experiment was measured using a low-resistance strain meter, and when the reinforcing steel ratio was 0.52%, a maximum strain of 0.00 mm was generated, requiring a yield strength of 75 k9/m or more. It turned out to be.

From the above, the effects of the present invention are as follows.

○} Yield strength of spiral reinforcing bar is 30k9/130k from fence
9/ By increasing the stress more than desired, the ultimate stress can be increased.

■ Yield strength 30k9/ compared with the same ultimate stress
The approximate reinforcing bar ratio is 1.18% and the yield strength of this invention is 130k9.
/The fence with a reinforcing bar ratio of 0.26% is the same, and the reinforcing bar ratio is 1.
/4.

The cross-section mirror of the reinforcing bar is approximately half that of the conventional one, and since the diameter of the reinforcing bar is thin, the weight is small, making it easier to transport and handle, and when comparing the same weight, a larger number of turns can be used.

{4' Pitch adjustment can be made without causing plastic deformation.

[5] The helical reinforcing bars stretch by themselves to a predetermined pitch and length due to their own elasticity, so when the compressed state is released on site, they will naturally expand and become approximately the required reinforcement arrangement, and can be secured by binding to the main reinforcing bars, etc. is extremely easy.

[Brief explanation of drawings]

Figures 1, 2 and 3 are elevational views of the reinforcement arrangement;
The figure is a column cross-sectional view, Figures 5 and 6 are elevation views and column cross-sectional views of other reinforcement arrangements, and Figure 7 is a schematic diagram of the spiral reinforcing bar manufacturing process.
Figure 8 is a schematic diagram of the test, and Figure 9 is a chart showing the relationship between the ultimate stress and the ratio of cut reinforcing reinforcing bars. 1, 1'...Spiral reinforcing bars, 2...Column main reinforcing bars,
3... Beam main reinforcing bar, 4... Head, 5...
...Reinforcing bar, 6...Induction heating coil, 7...
...Cooling device, 8...Heating coil for firing oven, 9...
- Wrapping machine, 10... Cooling mechanism. Figure 1 Figure 2 Figure 4 Figure 6 Figure 3 Figure 5 Figure 8 Figure 9

Claims (1)

[Claims] 1 A high-strength reinforcing bar with a yield strength of 130 kg/mm^2 or more is formed into a spiral shape and does not undergo plastic deformation even when fully compressed, and stretches by itself to a predetermined pitch and length due to its own elasticity. The helical reinforcing bars are compressed and arranged around the main reinforcing bars, and then released from the compressed state and expanded by themselves to be locked with the main reinforcing bars. reinforcement method.