JPS591863B2 - Spacer to hold column reinforcing bars in proper position - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to reinforced concrete (RC) or steel reinforced concrete (SRC) construction where there is floor plate formwork in the area from the column head to the column base on the upper floor. This invention relates to a spacer for holding main reinforcements in proper positions.

Conventionally, in order to maintain a predetermined cover thickness of the main reinforcement of a column when the cross section from the column head to the column base on the upper floor of an RC or SRC structure does not change, in Utility Model Application No. 53-53274, hoop An H-shaped spacer is used, which consists of a part that engages with the mold, and a formwork engaging part that is nailed to the formwork.

However, since nails are used, the attachment work is difficult and the installation time is therefore long.

If concrete is poured without accurately maintaining the position of the main reinforcing bars directly under the column bases on the upper floor, the main reinforcing bars of the upper floor columns may approach the formwork or protrude outside.
It becomes necessary to ``rebuild the columnar reinforcement'', which is a fatal flaw.

When the main reinforcement of a column is restated, if a large force is applied during an earthquake, the main reinforcement will stretch on the tension side and cause cracks in the concrete, and on the compression side the main reinforcement will buckle and push the concrete outward. It will look like a ``<'' and pop out.

Eventually, the concrete at the base of the column would break due to the repeated alternating loads during the earthquake.

Additionally, if the cross-section of a column in an RC or SRC structure becomes thinner as it goes up, the main reinforcement of the column must be bent at the point where it intersects with the beam to narrow it down so that it fits within the cross-section of the column on the upper floor.

The degree to which the column cross section is reduced is usually 5 centimeters from one layer to the next, and the bending slope of the main reinforcement varies depending on the beam composition, but it is generally a slight slope of 1/10 or less.

Generally, 19 to 25 mm is used for the main reinforcement of columns, and if the cross section of the column is different, the design drawings call for bending the main reinforcement, but since the slope is small, the beam is not bent. A construction method in which the shape of the upper and lower hoops is changed and these are tied to the main reinforcing bars to form a shape is currently in widespread use.

This construction method (the shape of the ζ-column reinforcement is not bad at the time of assembly, but
The main reinforcing bars tied in a bow are constantly subjected to a force that tries to return them to a straight line, so by the time the column formwork is assembled and the beam reinforcement is finished, the binding wires loosen due to vibrations during work, causing the main reinforcing bars to loosen. returns to the inside of the cross section in a nearly straight line.

This condition caused a decrease in strength because the stress center distance of the main reinforcements became smaller, and there was a risk that the concrete at the column head would break if a large force was applied during an earthquake.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to position the reinforcing bars of columns in RC or SRC structures from the column head to the column base on the upper floor in the appropriate position so as to obtain the correct overhang thickness. It is an object of the present invention to provide a spacer of the above-mentioned type which can be more easily placed and whose position can be reliably maintained during operation.

To achieve the above object, according to the present invention, two hook parts engageable with the hoops tied to the main reinforcement of the column are arranged parallel to each other and spaced apart, and are connected successively from each hook part. A straight line section is provided that runs horizontally and parallel to each other a certain distance downward, and at the end of each straight section, a curved section that comes into contact with the vertical column formwork is formed at a lower position than the hook section, A floor slab form contacting part having a plurality of chevron-shaped parts that comes into contact with the horizontal slab form is placed in a direction intersecting the direction of the two parallel straight parts and above the curved part on the opposite side to the hook part. The spacer is characterized in that both ends of the floor plate form abutting part are connected to each curved part via a connecting part having an acute angle so that the spacer is positioned at the same position, and each of the parts is integrally formed with a wire rod or a plate material. Just set it up.

Hereinafter, the present invention will be explained in more detail with reference to examples.

1 and 2 show a spacer 11 according to the invention (see also the plan view in FIG. 1).

4 indicates one of the main reinforcements of a large number of columns, 5a indicates a hoop tied to a large number of column main reinforcements near the height of the floor slab formwork, 9 indicates the column formwork, and 10 indicates the floor slab formwork. .

The spacer 11 according to the present invention is used where there is floor slab formwork, from the capital of the column to the base of the column on the upper floor.

The spacer 11 is hooked onto the hoop 5a, and another 2
two hook portions 11a, two straight line portions 11b extending horizontally and parallel from each hook portion, and a vertical pillar shape formed at the end of each of the straight portions at a position lower than the hook portion 11a. Curved portion 11c that comes into contact with frame 9
, two downward-facing chevron portions lid formed above this curved portion so as to come into contact with the horizontal floor slab formwork 10, and both ends of these chevron-shaped portions 11d as described above.
The connecting portion 11e has an acute angle and is connected to two curved portions 11c.

It is desirable that the portions lie and 11d in contact with the column formwork 9 and the floor slab formwork 10 be respectively coated with a rust preventive material to prevent rust from forming.

When the spacer 11 configured in this way is installed as shown in FIG. 1 (see also FIGS. 7 and 8), the hook portion 11
a and the curved portion 11C face each other and receive reaction forces from each other.

In this state, if the main reinforcement 4 and the hoop 5a try to approach the formwork side (in the direction of the arrow in Figure 4) due to external force, the spacer 1
Since the fulcrum of the first curved portion 11c and the axis of the hoop 5a are eccentric by an amount e, a clockwise rotational moment M acts, and the two chevron-shaped portions 11d of the spacer 11 press the floor slab formwork 10.

This prevents the spacer 11 from rotating and keeps it in a stable position at all times.

In reality, it is difficult to attach the hoop 5a on which the spacer 11 is hung at the same height on every pillar.
In the spacer 11 of the present invention, the connecting portion 11e between the curved portion 11c and the two chevron portions 11d is formed at an acute angle, so that it can follow changes in the height of the hoop 5a.

In addition, in the spacer of the present invention, two wire rods extending parallel to each other at a distance are joined by two chevron-shaped portions 11d, so that the spacer 11 receives horizontal external force that attempts to rotate or overturn it. remains stable even when

Next, if the cross section of a column in an RC or SRC structure is different on the upper and lower floors and becomes thinner on the upper floor, another means is used in addition to the spacer 11 in order to always maintain the main reinforcement of the column in an appropriate position. There must be.

This case will be explained below. Figure 3 a and b are RC
C10 Column 1, beam 2, floor slab 3 when the upper floor column 1' becomes thinner by Vl or V2 and the column width B0 changes to B2 on the upper floor
, is a vertical cross-sectional view showing the relationship between column main reinforcement 4 and hoop 5.
The correct form of the beam main reinforcements 6 is to arrange them as shown in the figure.

However, if the reinforcing bars of 19 mm or more used for the main column reinforcement 4, which are bent in the range D intersecting the beam 2, are bundled into the hoop 5 without bending due to the slight slope, the initial Ours looks correct, but by the time the reinforcement for beam 2 and floor slab 3 is finished, the bent parts of the main reinforcement will return to straight lines as shown in Figure 3 C and D, so hoop 5 The tied wire gradually loosens, and the stress center distance becomes j2<j□
, j4>ja, and the general tendency is for the throat to be smaller than the design dimension.

To prevent this, as shown in Figures 4 to 6,
The outer periphery of the main reinforcement drawing frame 7 is
Place it on the inside of the box and tie it with a binding wire to secure it.

This main reinforcement drawing frame 7 is made by welding small angle irons,
It consists of a frame portion 7a whose outer periphery is shaped so as to come into contact with the inside of a large number of column main reinforcements 4, and a frame portion 7b.

At the corner of the main reinforcement drawing frame 7, corner main reinforcement supports 7c made of slightly larger angle iron are fixed by welding or the like so as to extend in the same direction as the axis of the corner main reinforcements in order to receive the corner main reinforcements 4'.

This can prevent the main corner reinforcing bars 4' from being bent in the XYz directions.

In addition, as can be clearly seen from FIG. 6, there is also a V-shaped notch 7d in the abdomen of the corner main reinforcement 7c from the tip of the angle iron to the axis of the corner main reinforcement 4' in order to facilitate binding with the main reinforcement. is provided.

In addition, the frame portion 7a of the main reinforcement drawing frame T and the frame portion 7b are designed so as not to adversely affect the filling properties of concrete, and when dropping the beam reinforcement into the formwork, the beam reinforcement 6 is attached to the column. In order to be able to slide even if the tip edge part 6a of the part to be fixed touches, it is desirable to weld the angle iron with the top part facing inside and each flange forming an angle of 45 degrees with the horizontal plane.

When the main reinforcement frame 7 is fixed inside the main reinforcement of the column head,
The main reinforcing bars 4' of the columns 1' on the upper floor are inclined inward in cross section as shown in Figure 9a.

If this is simply tied into a hoop as in the past, the binding wire tends to loosen due to vibration during work or poor tightening of the binding wire, and the main reinforcement tends to return to a diagonal straight line, just like the column head main reinforcement mentioned above. be.

The time to assemble the reinforcing bars for the columns on the upper floor is several days after the concrete for the lower floor is poured, and the concrete has not yet achieved its full strength.

At this point, rectifying the main reinforcing bars, which have returned to a diagonal straight line, to be vertical would destroy the concrete around the main reinforcing bars and break the adhesive force between the reinforcing bars and the concrete, creating a structurally defective part.

In order to avoid this situation and to raise the main reinforcement vertically from the state shown in FIG. 9a, it is sufficient to install a frame 7' of the same type as the main reinforcement drawing frame 7 on the upper floor as shown in FIG. 9b.

With the column main reinforcement drawing frames 7 and 7' provided on the column capital and the column base on the upper floor, in order to obtain an appropriate cover thickness for the reinforcing bars, the above-mentioned method of the present invention is installed near the height of the floor slab formwork 10. spacer 11
must be established.

However, if the cross-section of the column base on the upper floor is narrower than the cross-section of the column capital, as in this embodiment, it differs from the first embodiment in which the column capital and the column base on the upper floor have the same cross-section in the following points. You have to be careful what happens.

In other words, the column main reinforcement 4' of the column base is a part that starts to narrow from the column head in Figures 3a and 3b and rises vertically from the point where it reaches the inside of the cross section by Vo or V2, and as shown in Figures 7 and 8. As is clear from the figure, the hoop 5 near the height of the floor slab formwork 10
A is used that is smaller than the hoop 5C of the column capital, but in this case, the column formwork 9 rises to the same size and engages with the floor slab formwork, so the hoop 5a and the column formwork 9 The cover thickness is C2, which is the sum of the reinforcing bar cover thickness C1 and Vl shown in FIG. 1, which is larger than the cover thickness when the cross section of the column capital and the column base on the upper floor are the same as in the first embodiment.

Therefore, in this embodiment, a spacer 11 is used in which the straight portion 11b is longer by vo than in the first embodiment.

As shown in Figures 7 and 8, when the sides of the column and beam are aligned, or when the spacer 11 cannot be placed around the entire circumference of the column base, the pulling fitting 14 is used as an auxiliary means. It is necessary to install it above the top end 16 of the concrete floor slab to correct the torsion of the column reinforcement.

The pulling fitting 14 includes a hook portion 14a for hooking onto the main corner bar 4 of a column, a protrusion portion 14b with a hole fixed to the rear end of the hook portion, and a hole in the protrusion portion 14b to be attached with a screw. The bolt 14c has a pointed end 14d bent at a right angle.

When in use, first hook the hook portion 14a onto the main corner reinforcement 4', then pass the bolt through the hole in the protruding portion 14b and attach the pointed end 1.
Drive 4d into the column formwork.

Adjust the length by turning the nut H4e passed through the bolt, and fix by tightening the thumbscrew 14f while sandwiching the protruding portion 14b.

This pulling fitting 14 can be removed and collected before pouring concrete up to the capital of the column and starting work on the upper floor, and can be used for next time.

In addition, the hoop between the capital of the column and the base of the column on the upper floor.

The reinforcement is placed horizontally and tied around the main reinforcement, but if it cannot be reached from above like hoop 5d,
It is preferable to use a hoop receiver 15 (FIG. 10) which receives the hoop 5d at a predetermined position.

The hoop receiver 15 is made of wire, and has a straight portion 15 at its tip for applying to the outside of the hoop 5c of the column head.
There is a.

Since the hoop 5c of the column head is connected to the main reinforcement 4 before the column formwork 9 is assembled, the hoop receiver 15 is set using the hoop 5c as a ruler.
The straight end portion 15a of the can be hooked.

This straight portion 15a bends inward at 15b, and then bends again at 15c, which passes through an interval of diameter Wako of the hoop 5d, in the opposite direction to the tip straight portion 15a, and the intermediate straight portion 15
It continues to d.

A hook portion 15e is formed at the top of this straight portion 15d to be hooked onto the hoop 5b of the column base, and it is further bent laterally so as to be parallel to the hoop 5b of the column base, and a curved portion 15f is formed downward. A top straight portion 15g is formed and extends upwardly at the hoop 5b of the column base, and further extends from there along the hoop 5b.

Further, a hook '15h is attached to the intermediate straight portion 15d at a height apart from the capital hoop 5c by a specified distance so as to face outward.

When using, attach the top straight section 15g to the column base 7"5
By fixing to b with a binding wire, the hook portion 15h for receiving the hoop can be oriented in a direction perpendicular to the hoop.

Note that 13 indicates a conventional spacer used in the column formwork on the opposite side to the side where the floor slab formwork is located.

Next, regarding the case where the cross section of the column base on the upper floor is thinner than the cross section of the column head, the spacer 11 of the present invention
The procedure for using the above will be explained with reference to FIG. 9 in connection with the work of assembling reinforcing bars and formwork.

1) From the foundation or lower floor to the main reinforcement 4 of the literary pillar,
Assemble the hoop 5 to the lower end of the beam 2 (Figure 9a).

2) Attach the main reinforcing frame 1 to the main reinforcing bars at the same height as the formwork 12 at the bottom of the beam using a wire that is thicker than usual (Figure 9a).

3) Hook the conventional chevron-shaped spacer 13 to the hoop to form the covering thickness of the columnar surface (Fig. 9a and Figs. 1 and 8).

4) Assemble formwork 9, 12, 10 for columns, beams and deck slabs (Figure 9a).

5) Attach the hoops 5a to the height of the floor slab formwork 10, and then temporarily fix several hoops to be used in the beam area at the height positions of the floor slab formwork 10 in order of height. (Figure 9b).

6) Attach the main reinforcement frame 7' to the column main reinforcement 4' on the upper floor (
Figure 9b).

7) Place the spacer 11 near the corner of the hoop 5a in a certain part of the floor slab formwork 10 (FIG. 1).

The procedure is to first hook the hook portion 11a of the spacer 11 onto the hoop 5a, and place the column form contacting portion 11C on the ten floor slab forms.

Gently push the upper floor main reinforcement 4' or the already installed upper floor main reinforcement frame 7' with your hand in the direction opposite to the arrow in Figure 1.
The column formwork abutting portion 11c of the spacer 11 is connected to the floor slab formwork 10.
Drop more.

When the hand is released, the parts lie and 11d abut against the formworks 10 and 9 of the floor slab and column, respectively, to ensure the cover thickness (Fig. 9b).

8) If necessary, use the pulling fitting 14 to correct the twist of the column (Figure 9b).

9) After assembling the main beam reinforcing bars 6 and stirrups 11, they are dropped into the formwork 12 at the bottom of the beam (Figs. 9b to 9c).

10) Lower several hoops in the beam area that were temporarily fixed earlier and tie them to the column main reinforcement at the same intervals.

If the beam size is large and it seems that the lower hoops cannot be tied together, hook the hoop receiver 15 on the column head hoop 5c and the column base hoop 5c in advance, and drop them in order from the lower hoop ( Figure 9c).

n) Attach the abdominal reinforcement of the beam to the column and proceed to the next work such as arranging small beams and slab reinforcement.

The spacer of the present invention can be easily and quickly placed, and is always stable no matter where external force is applied in the horizontal direction during work, making it possible to reliably maintain the concrete cover thickness over the column reinforcement. .

In addition, even if the cross section of the column pedestal on the floor above the column capital is thin, by using the column reinforcement drawing frame in combination with the spacer, the cross section of the column capital and column base can be reduced without having to bend the main reinforcement. can be placed correctly in position and maintained in that position during operation.

[Brief explanation of the drawing]

Fig. 1 is a partially enlarged view of the column base using the spacer of the present invention, Fig. 2 is a rear view taken along line -H in Fig. 1, and Figs. 3a to 3d are the columns and beams. Fig. 4 is a schematic plan view of the main reinforcing frame placed in the column capital, and Fig. 5 shows the relationship between the main reinforcing frame, the main reinforcement, and the hoop. Fig. 6 is a partially enlarged vertical sectional view taken along the line Vl-Vl in Fig. 5, and Figs. 7 and 8 show the arrangement of spacers and main reinforcement frames near the column capital and column base. Figure 7 is a plan view taken along the line ■-■ in Figure 8, Figure 8 is a longitudinal sectional view taken along the line ■11-■ in Figure 1, and Figure 9a is a diagram showing the relationship.
Figures 9 to 9c are longitudinal cross-sectional views showing the parts where the columns and beams meet, and an assembly diagram showing the order of use of spacers, main reinforcement frames, etc., and Figure 10 is a state in which the hoop receiver is used as a panel zone. FIG. 4, 4------Main bars of columns, 5a, 5b, 5c, 5d
...Hoop, 9...Column formwork, 10...
...Floor slab formwork, 11...Spacer, 11
a...Hook part, 11c...Curved part, 11d...Sleeve chevron shaped part, 11e...Connection part, γ...Column main reinforcement drawing frame.

Claims (1)

[Claims] 1 A spacer that is tied to the main reinforcement of a column and is used where there is floor plate formwork in a reinforced concrete or steel-framed reinforced concrete structure from the column head to the column base on the upper floor. Two hook parts 11a that can engage with the hoop 5a are arranged parallel to each other and spaced apart, and a straight line part 1 runs horizontally and parallel to each other continuously from each hook part by a constant distance downwardly.
1b, and a hook portion 11a is provided at the end of each straight portion, and a curved portion 11C that comes into contact with the vertical column form 9 is provided at the end of each straight portion.
A floor plate form contacting portion formed at a lower position and having a plurality of chevron-shaped portions 11d that abuts the horizontal floor plate form 10 is curved in a direction intersecting the direction of the two parallel straight portions 11b. Both ends of the floor slab form abutting portion are connected to each curved portion 11c via a connecting portion 11e having an acute angle so as to be located above the portion 11C and on the opposite side of the hook portion 11a, and the above-mentioned portions are connected. A spacer characterized by being integrally formed of a wire rod or a plate material.