JP2003003573A - Method for connecting reinforced concrete precast beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for connecting a reinforced concrete precast beam capable of connecting a large beam and a grid beam with high precision keeping a prescribed rigidity, without fixing a lower end main reinforcement of the grid beam to the large beam. SOLUTION: When connecting the large beam 10 and the grid beam 20, the large beam 10 and the grid beam 20 are changed into PCa. An upper end main reinforcement 20a of the grid beam 20 is bent, and this is inserted into a sleeve type coupler 10s buried beforehand in a connecting part 10A of the large beam 10. After a mortar 10m with high strength is poured into the sleeve type coupler 10s and the upper end main reinforcement 20a is fixed to the large beam 10, the large beam 10 and the grid beam 20 are unified by a post- cast concrete 10n.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining reinforced concrete precast beams, and more particularly to a method for joining grid beams made of precast reinforced concrete between girders.

[0002]

2. Description of the Related Art In recent years, with the development of the electronics industry for producing highly integrated IC products, the construction industry itself has come to belong to the precision industry, and a factory equipped with a production room in which precision machinery and the like are arranged. When designing and constructing, etc., measures against fine vibration and air cleaning are required. For example, with regard to indoor air, so-called clean room facilities are often adopted and the grade is being improved more and more. Therefore, clean air with few dust particles is supplied to the airtight room and the work surface is Is set up with a grating to blow out the precipitated dust. Therefore, on the floor of the electronic factory, for example, as shown in FIGS. 5A and 5B, the girders 10 are arranged in a frame shape between the pillar members 30,
A lattice beam (waffle slab) in which small beams 21 (21a to 21d and 21A to 21D) are arranged in a lattice pattern between the large beams 10 and 10 and a blow-through portion 22 for flowing air is provided.
It is constructed with 20 frames.

In the case of constructing a floor having the above-mentioned structure, conventionally, a form of the girder 10 and the lattice beam 20 is assembled, the beam reinforcing bars are dropped into the form, and then the ready-mixed concrete is used as the form. It was a general construction method to place it in the frame. Further, by improving this, by attaching a slab formwork to the lower end of the lattice beam 20 and installing a formwork such as "styrofoam" or "corrugated formwork" in the blow-through part 22, the side formwork of the lattice beam 20 is saved. The construction method was also devised.

[0004]

SUMMARY OF THE INVENTION In the above conventional method,
When designing the portion where the beam 21 is attached to the girder 10, it is generally designed assuming the pin state, and both the upper and lower main bars (not shown) of the lattice beam 20 are fixed in the large beam 10. Therefore, the joint between the girder 10 and the girder 21 is rigidly joined to some extent. Therefore, the end of the lattice beam 20, which can be regarded as a slab portion, is in a state close to a rigid joint, which is convenient for a high-integrated IC electronic factory that mounts a vibration-insensitive precision device on the floor because the vibration is small. However, in any of the above-mentioned conventional construction methods, a large amount of fresh concrete has to be placed on site, which results in poor workability and a long construction period. On the other hand, with the improvement of precast (hereinafter, referred to as PCa) technology of a reinforced concrete structure (hereinafter, referred to as RC), the above PCa member of RC is
It has come to be widely used as a member such as a column, a beam, a floor or a wall. However, when both the large beam 10 and the small beam 21 are made of PCa beams, the lower end main bar of the lattice beam 20 is fixed to the large beam 10. It was very difficult to plan.

The present invention has been made in view of the conventional problems, and joins a large beam and a lattice beam with high precision and while ensuring a predetermined rigidity without fixing the lower end main bar of the lattice beam to the large beam. An object of the present invention is to provide a method for joining reinforced concrete precast beams that can be used.

[0006]

Means for Solving the Problems As a result of earnest studies, the inventors have considered that the grid beam is a floor slab, so that it is sufficient to support a load (long-term load). Since the upper end is pulled and the lower end is compressed, it has been found that the above problems can be solved by fixing only the upper main bars of the lattice beam to the large girder and achieving the PCa without fixing the lower main bar to the large girder, and thus the present invention was achieved. It is a thing. That is, in the method for joining reinforced concrete precast beams according to claim 1 of the present invention, the large beam and the lattice beam are both P
In addition to Ca, a hole is formed at the joint position between the large beam and the lattice beam, and the upper main bar of the lattice beam is bent and inserted into the hole to fix it. , Without fixing the bottom main bar to the girder,
Since the lattice beams can be joined accurately while ensuring a predetermined rigidity, it is possible to rationalize the construction and shorten the process. Further, in the method for joining reinforced concrete precast beams according to claim 2, in order to further improve the joining strength, a sleeve joint is embedded in the hole, and the upper end main bar of the lattice beam is bent and inserted into the sleeve joint. The feature is that it is fixed.

According to a third aspect of the present invention, there is provided a method for joining a reinforced concrete precast beam, wherein mortar is injected into the hole or sleeve joint to fix the inserted upper main bar, and then the large beam and the lattice beam are crossed. It is characterized by post-casting concrete on the part and integrating the girder and the grid beam.By this, the rigidity of the joint can be improved, and the post-cast concrete is Since only the intersection of the beams is required, it is possible to secure the rigidity of the joint with less work.

A method for joining reinforced concrete precast beams according to a fourth aspect is characterized in that an uneven portion called a shear cotter is provided on the end face of the joint portion of the lattice beam, which acts on the lattice beam. The shearing force can be effectively transmitted to the girder, and the strength of the joint can be further improved.

The method for joining reinforced concrete precast beams according to claim 5 is characterized in that the grid beams are divided into a plurality of grid beam members to form PCa in order to facilitate transportation or lifting of the grid beams. To do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. 1 (a) to 1 (c) are schematic views showing a method for joining reinforced concrete precast beams according to an embodiment of the present invention, wherein FIG. 1 (a) is a plan view of a joint portion,
(B) is a vertical cross-sectional view of the girder, and (c) is a cross-sectional view of the girder. In each drawing, 10 is a girder that is constructed between pillar members 30, and 10a to 10c are the upper end main bar, the lower end main bar, and the shear reinforcing bar of the girder 10, respectively. Further, 20 is a lattice beam constructed between the large beams 10 and 20a is an upper main bar,
20b is a lower end main bar. In the large beam 10, the upper end main bar 10a is exposed only at the joint 10A to which the lattice beam 20 is attached, and the other part is made PCa. Further, a cutout portion 10C for hanging the lattice beam 20 is formed on the side surface 10B of the joint portion 10A. Further, on the side of the joint portion 10A opposite to the cutout portion 10C sandwiching the center line of the girder 10, the upper end main bar 2 of the lattice beam 20 is provided.
A plurality of (here, three) sleeve type joints 10s for fixing 0a are embedded. Lattice beam 20 is also PCa
The upper end main bar 20a thereof is projected from an end face 20A which is a joint portion with the girder 10 and is bent downward substantially at a right angle, and the lower end main bar 20b is not projected from the end face 20A, In the vicinity of the end face 20A, the upper end main bar 20a is bent vertically. Furthermore, in order to effectively transmit the shearing force to the girder 10,
The end face 20A has an uneven portion 2 called a sheer cotter.
0B is formed.

Next, the construction procedure will be described. First,
The girders 10 are joined to the pillar member 30. At that time, in order to ensure the accuracy of the joint position with the lattice beam 20,
The joining of 0s is performed in the joining portion of the pillar member 30. When joining the girder 10 and the lattice beam 20, each of the bent upper main bars 20a of the grate beam 20 is embedded in the joining portion 10A of the girder 10 with the sleeve type joint 10.
While being inserted into s, the end surface 20A of the lattice beam 20 is placed on the girder 10 while being aligned with the cutout portion 10C of the girder 10. At this time, the upper main bar 20a of the lattice beam 20 is
The cross beam is extended to the opposite side beyond the center line of the cross section and fixed in the sleeve type joint 10s. After that, the high-strength mortar 1 is placed in the sleeve type joint 10s.
0m is injected and the upper end main bar 20a is fixed to the girder 10. Next, a stop frame (not shown) is attached to the corner where the girder 10 and the lattice beam 20 intersect, and ready-mixed concrete is cast from the upper part of the girder 10 to integrate the girder 10 and the lattice beam 20. At this time, be careful that concrete also wraps between the end surface 20A of the lattice beam 20 and the side surface 10B of the girder 10. In this post-cast concrete 10n, girder 1
Since the upper end main bar 10a and the shear reinforcing bar 10c of 0 and the upper end main bar 20a of the lattice beam 20 are driven in, sufficient joint strength can be secured. Therefore, the PC
After setting a, it is not necessary to move or newly install a reinforcing bar, and the amount of concrete to be placed is small, so that the construction can be rationalized and the process can be shortened. Further, since the shear cotter 20B is formed on the end surface 20A of the lattice beam 20, the joint strength between the large beam 10 and the lattice beam 20 by the post-cast concrete 10n can be further improved, and the lattice beam 20 can be acted on. The shearing force generated can be effectively transmitted to the girder 10.

In an electronic factory that produces highly integrated IC products, the span of the pillar member 30 in FIG. 5 is about 6.0 to 8.0 m, so that, for example, as shown in FIG. If a lattice beam 20 having four beam girders 21 vertically and horizontally is installed between them, the interval between the beam girders is 1.2 to 1.6.
If the width of the beam 21 is 30 cm, the size of the blow-through portion 22 is 0.9 to 1.3 m. If the height of the beam 21 is assumed to be 90 cm and the lattice beam portion is made of PCa, the weight thereof becomes 24.9 to 34.2 ton, which cannot be lifted by an ordinary lifting machine. Therefore, in that case, in order to reduce the weight, as shown in FIG. 3, the lattice beam 20 is decomposed into, for example, two lattice members 201 and 202 to form PCa, and the lattice members 201 and 202 are mechanically joined. After joining with 203 or the like, a shear reinforcing bar may be wound around the main bar and integrated with the post-cast concrete 204. It should be noted that the grid beam 20 may be divided into any number,
When the number of divisions is increased, the weight of each grid member is reduced, but the amount of joints and post-cast concrete is increased. Therefore, the number of divisions is preferably selected in consideration of workability.

As described above, in this embodiment, the girder 10 is used.
When joining the girder and the girder beam 20, the girder 10 and the grate beam 20 are made into PCa, the upper end main bar 20a of the grate beam 20 is bent, and this is preliminarily embedded in the girder joint 10A. After inserting into 10s and injecting high-strength mortar 10m into the sleeve type joint 10s to fix the upper end main bar 20a to the girder 10, the girder 10 and the lattice girder 20 are integrated with the post-casting concrete 10n. Therefore, the girders 10 and the lattice girders 20 can be joined with high precision and while ensuring a predetermined rigidity without fixing the lower end main bars 20b to the girders 10. Furthermore,
Since the bar arrangement after PCa setting is not required, the construction can be rationalized and the process can be shortened. In addition, this method
Since the Ca rate is high, it is possible to improve the quality of the construction product (here, the floor).

In this embodiment, the case where the lattice beam 20 is attached only to one side of the girder 10 has been described, but as shown in FIGS. 4 (a) and 4 (b), the same method can be used. The lattice beams 20P and 20Q can be joined to both sides of the girder 10. However, in this case, the lattice beam 20
It is necessary to slightly bend the upper end main bars 20p and 20q of P and 20Q on the joint surface 10A of the girder 10 in the extension direction of the girder 10 so as not to intersect with each other (see FIG. 4A). Further, in the above example, the upper end main bar 20a of the lattice beam 20 is bent and inserted into the sleeve joint 10s embedded in the joint 10A of the girder 10 to be fixed, but the joint 10A is simply provided with a hole. Alternatively, the upper end main bar 20a may be bent and inserted into the hole to fix it. In this case, it is desirable to reinforce the hole by preliminarily providing a reinforcing spiral streak in the hole so as to secure the bonding strength.

[0015]

As described above, according to the present invention, the large beams and the lattice beams are made into PCa, and the holes are formed at the joint positions of the large beams with the lattice beams so that the upper ends of the lattice beams are formed. Since the main bar is bent and inserted into the hole to be fixed, the girder and the lattice girder can be accurately and efficiently joined to the girder while ensuring a predetermined rigidity. It can be shortened. Further, by embedding a sleeve joint in the hole and bending and inserting the upper end main bar into the sleeve joint to fix the sleeve joint, the joint strength can be further improved. Further, since only the intersection of the large beam and the lattice beam is post-cast with concrete to be integrated, the rigidity of the lattice beam can be secured with a small amount of work.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of joining PCa beams according to the present embodiment.

FIG. 2 is a diagram showing a PCa-made lattice beam according to the present embodiment.

FIG. 3 is a diagram showing an example in which a lattice beam is divided into PCa.

FIG. 4 is a diagram showing a method of mounting lattice beams on both sides of a large beam.

FIG. 5 is a diagram showing an example of a lattice beam structure.

[Explanation of symbols]

10 girder, 10A girder joint, 10B girder side surface, 10C notch, 10a girder upper end bar, 1
0b Main girder bottom reinforcement, 10c Girder shear reinforcement,
10m mortar, 10n post-cast concrete, 10
s Sleeve joint, 20 Lattice beam, 20a Lattice beam upper end main bar, 20b Lattice beam lower end main bar, 20A Lattice beam end face, 20B Concavo-convex part (shear cotter), 21 Small beam, 22 Blowing part, 30 Column member.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiji Sakai             No. 2 Tsukutocho, Shinjuku-ku, Tokyo Co., Ltd.             Kumagai Gumi Tokyo Head Office F-term (reference) 2E125 AA14 AA17 AB12 AC02 AG03                       AG04 AG13 AG28 BA34 CA79                       CA82

Claims (5)

[Claims] 1. A large beam and a lattice beam are both made into PCa, a hole is formed in a thickness direction of a joint position of the large beam and the lattice beam, and an upper end main bar of the lattice beam is bent and inserted into the hole, A method for joining reinforced concrete precast beams, characterized in that they are fixed. 2. The reinforced concrete precast beam according to claim 1, wherein a sleeve joint is embedded in the hole, and the upper end main bar of the lattice beam is bent and inserted into the sleeve joint so as to be fixed. How to join. 3. After injecting mortar into the hole or the sleeve joint to fix the inserted upper main bar,
The method for joining reinforced concrete precast beams according to claim 1 or 2, wherein concrete is post-cast at the intersection of the large beam and the lattice beam to integrate the large beam and the lattice beam. 4. The joining method for a reinforced concrete precast beam according to claim 1, wherein an uneven portion is provided on an end face of the joining portion of the lattice beam. 5. The joining method for a reinforced concrete precast beam according to claim 1, wherein the lattice beam is divided into a plurality of lattice beam members and made into PCa.