JP3072604B2 - Precast reinforced concrete beam and its joining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast reinforced concrete beam which is preferably used when joining a precast reinforced concrete beam to another member such as an SRC-structured column mainly in the construction of a precast concrete structure of middle and high layers. Related to the joining method.

[0002]

2. Description of the Related Art Conventionally, as a method of joining a precast reinforced concrete beam to another member such as a column having an SRC structure, a method of joining via a joining steel material protrudingly attached to a joining end face of the precast reinforced concrete beam. Has been widely adopted. This joining steel is
When a precast reinforced concrete beam is manufactured, it is fixed to the precast reinforced concrete beam by embedding a part of the precast reinforced concrete beam and welding it to an anchor bar, and then pouring concrete. Then, a bolt hole is provided in advance in the projecting portion of the joining steel material, and after the joining steel material is adjusted to another member (for example, a column bracket) or the like, a bolt is inserted through the bolt hole, and the like.
The connection between the precast reinforced concrete beam and other members is performed.

[0003]

However, according to the above-mentioned construction method, since the joining steel material is fixed to the precast reinforced concrete beam in advance and its projecting dimension cannot be changed, the joining method is not used during the production of the precast reinforced concrete beam. The installation accuracy of steel materials must be strictly controlled. This is because if there is an error in the mounting position of the joining steel material, joining with other members becomes extremely difficult during construction on site. In such a case,
It is necessary to take measures such as drilling bolt holes,
It takes a lot of time and also greatly extends the construction period.

[0004] The present invention has been made in view of such circumstances, and a precast reinforced concrete beam capable of reducing the strictness of the mounting accuracy of the joining steel material and simplifying the on-site construction. And a joining method thereof.

[0005]

A precast reinforced concrete beam according to the present invention is constructed such that a joining steel material is movably embedded so as to be protruded from an end face of a joint and to be able to adjust its projecting dimension. And

Further, in the method of joining a precast reinforced concrete beam according to the present invention, a precast reinforced concrete beam in which a joining steel material is movably embedded so as to protrude from an end face of the joint and to adjust the projecting dimension can be constructed. In doing so, the joining steel material is joined to another member while adjusting the projecting dimension of the joining steel material, and then the joining steel material is fixed to anchor bars prearranged on a precast reinforced concrete beam. And

[0007]

According to the precast reinforced concrete beam and the joining method of the present invention, a joining steel material is movably embedded in the precast reinforced concrete beam so as to be protruded from the joint end face and the projecting dimension can be adjusted. Therefore, at the time of on-site construction, the projecting dimension of the joining steel material can be appropriately adjusted according to the distance from the joining end surface to another member to be joined. Therefore, when manufacturing the precast reinforced concrete beam, even if the mounting accuracy of the joining steel material is not strictly controlled, the joining with other members can be easily performed, and the work can be simplified,
Workability is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A precast reinforced concrete beam according to the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of a precast reinforced concrete beam, showing a structure near an end. Precast reinforced concrete beams (hereinafter
Abbreviated as PC beam. 1) is composed of an SRC (steel reinforced concrete) structure or RC (reinforced concrete) structure. The upper part of the exposed portion 3 on which the concrete slab is placed and then cast in place after the floor slab is put on it is not cast with concrete 2.
It has been. A stirrup bar 4 made of a square hoop or a spiral hoop is arranged on the PC beam 1 with its upper end protruding from the upper surface of the PC beam 1 into the exposed portion 3. An upper main bar 5 is arranged on the inner upper portion of the stirrup bar 4, and a lower main bar 6 is arranged on the inner lower portion of the stirrup bar 4, respectively. Upper main bar 5 is PC
It is exposed from the upper surface of the beam 1. In addition, below the upper main bar 5, an anchor bar 7 that is arranged obliquely downward with a slight gradient toward the joint end surface 1a is provided so as to be exposed from the upper surface of the PC beam 1.

The PC beam 1 has a joint end face 1
The joining steel material 8 is movably embedded so as to protrude from a and adjust the protruding dimension. That is, an appropriate release agent or the like is applied to the outer peripheral surface of the joining steel material 8, and the adhesion with the surrounding concrete 2 is cut off. It is movable along the longitudinal direction. Reference numeral 9 in FIG. 2 denotes a gap formed on the far end side of the joining steel material 8 when the joining steel material 8 moves in a direction protruding from the joining end surface 1a. It is necessary that the joining steel material 8 be buried sufficiently deep without falling off from the PC beam 1 and providing the necessary strength to the PC beam. An H-shaped steel composed of upper and lower flanges 8a and 8b and a web 8c is used as the joining steel material 8, and the upper surface of the upper flange 8a is exposed to the upper exposed portion 3 of the PC beam 1. Around the portion in which the joining steel material 8 is embedded, a rectangular band-shaped reinforcing band plate 10 is embedded with its upper end and lower end in contact with the inside of the upper main reinforcement 5 and the lower main reinforcement 6, respectively. The reinforcing steel plate 8 reinforces the joining steel material 8. In addition, several bolt holes 11 are provided in the web 8c on the tip end side of the joining steel material 8.

Next, a method for joining precast reinforced concrete beams of the present invention will be described.

First, in a factory or the like, the PC beam 1 having the above configuration is manufactured. When manufacturing the PC beam 1, the specified formwork
Necessary bar arrangements such as stirrup bar 4, upper main bar 5, lower main bar 6, anchor bar 7, etc. are performed in (not shown).
A joining steel material 8 made of a mold steel is disposed at a predetermined position. The joining steel material 8 is previously coated on the entire outer peripheral surface thereof with a release agent or the like having a property of weakening adhesion to concrete.
Around the joining steel material 8, a reinforcing strip plate 10 is attached so that its upper end and lower end are in contact with the inside of the upper main bar 5 and the lower main bar 6, respectively.

The concrete 2 is cast and the PC beam 1
To form While the concrete 2 is semi-hardened, the joining steel 8 is pushed or pulled along the longitudinal direction of the PC beam 1 to completely cut off the adhesive force between the joining steel 8 and the concrete 2. By this, concrete 2
After hardening, the joining steel material 8 becomes the joining end face 1 of the PC beam 1.
It is embedded movably so that it can protrude from a and its protruding dimension can be adjusted.

The PC beam 1 manufactured as described above is carried to the site and attached to a predetermined position. In this embodiment, the PC
The beam 1 is disposed between the columns 12, 12, and the joining steel 8 and the bracket 13 of the column 12 are joined. At this time, pillar 1
The joining steel material 8 is pulled out from the joining end face 1a of the PC beam 1 by a predetermined size in accordance with the distance between 2 and 12, and the protrusion dimension of the joining steel material 8 is adjusted. After joining the joining steel member 8 and the bracket 13, reinforcing plates are applied to both sides of the joining member 8 from both sides of the web 8 c of the joining steel member 8 and fixed by bolting, and then the upper exposed portion of the PC beam 1. 3
The upper surface of the joining steel material 8 that is exposed to the outside and the anchor bar 7 are welded and fixed. Then, in some cases, PC
Concrete is cast between the joint end face 1a of the beam 1 and the column 12, and the PC beam 1 and the column 12 are connected.

Next, after placing the floor slab 14 on the upper part of the PC beam 1, concrete is poured into the upper exposed portion 3 of the PC beam 1 to complete the construction of the beam.

As described above, according to the precast reinforced concrete beam of this embodiment and the joining method thereof,
At the time of on-site construction, the projecting dimension of the joining steel material 8 can be appropriately adjusted according to the distance from the joining end face 1a of the PC beam 1 to another member (column 12) to be joined. Therefore,
At the time of manufacturing the PC beam 1, even if the mounting accuracy of the joining steel material 8 is not strictly controlled, the joining with another member (the column 12) can be easily performed. Therefore, the PC at the factory
In addition to improving the workability by relaxing the strictness of the work when manufacturing the beam 1, the workability at the time of construction on the site is also improved,
Work can be simplified and labor can be saved.

Next, a method of transmitting a bending moment generated in the PC beam 1 during an earthquake or the like will be described with reference to FIGS.

FIG. 3 shows a structure in which the PC beam 1 and the column 12 are joined by a joining steel material 8. When a bending moment as shown by a hatched portion in FIG. 4 acts on the PC beam 1 at the time of an earthquake or the like, the bending moment is transmitted to the column 12 by the joining steel material 8 prying the PC beam 1.

FIG. 5 schematically illustrates this by exchanging a force between the joining steel material 8 and the PC beam 1. 5 (b) and 5 (c), the dashed line indicates P
This is a bending moment distribution acting on the entire C beam 1. When such a bending moment acts on the PC beam 1, a force indicated by a black arrow in FIG. As a result, a bending moment as shown by the hatched portion in FIG. Further, since the reaction force of the force indicated by the black arrow acting on the joining steel material 8 acts on the PC beam 1, the PC beam 1
A bending moment is generated as shown by the hatched portion in FIG. As a result, when the PC beam 1 is considered as a whole, the bending moment and the shearing force generated in the PC beam 1 due to an earthquake or the like are transmitted to the column 12. Thus, the joining steel material 8
Is embedded in the PC beam 1 having a sufficient depth, the bending moment generated in the PC beam 1 is transmitted to the column 12 even though there is no adhesive force between the joining steel material 8 and the concrete 2. be able to. Therefore, according to such a joint structure of the PC beams 1, an anti-vibration effect is exerted against an earthquake or the like.

The tensile force acting on the PC beam 1 is transmitted by the anchor bar 7 joined to the joining steel member 8 and the slab bar of the floor slab 14 disposed above the PC beam 1.
Further, the compressive force acting on the PC beam 1 is transmitted by concrete cast between the joint end face 1a of the PC beam 1 and the column 12.

Next, another embodiment of the precast reinforced concrete beam of the present invention and its joining method will be described with reference to FIG. 6 and FIG. In this embodiment, an example in which the precast beam 16 is joined to the column 18 using prestress is shown. The precast beam 16 is placed on the bracket 19 of the column 18 and protrudes from the joint end face 16a. The joining steel material 17 is made up of columns 18 by PC steel rods 20.
By crimping to the precast beam 16 and the column 18
And are joined.

As described above, when the precast beam 16 is joined, when the joining steel 17 is pressed against the column 18, the joining steel 17 receives a tensile force. Therefore, the joining steel material 17 necessarily escapes from the joining end face 16a of the precast beam 16 by a predetermined dimension. Therefore, the joining of the precast beam 16 can be performed without generating a tensile force in the concrete of the precast beam 16. Therefore, there is an advantage that prestress can be applied to the precast beam 16 in advance.

The precast reinforced concrete beam of the present invention and the method of joining the same are not limited to the above-described embodiment, and the specific configuration such as the shape of each member and the construction procedure is as follows.
It can be changed as appropriate for implementation.

For example, in the above-described embodiment, the construction when joining the PC beam to the column has been described as an example. However, the present invention may be applied to the case where the PC beam is joined to a member other than the column.

[0025]

As described above, according to the precast reinforced concrete beam of the present invention and the joining method thereof,
At the time of on-site construction, the projecting dimension of the joining steel material can be appropriately adjusted according to the distance from the joining end face to another member to be joined. Therefore, when manufacturing the PC beam, even if the mounting accuracy of the joining steel material is not strictly controlled, the joining with other members can be easily performed. Therefore, the strictness of the work at the time of manufacturing the PC beam at the factory can be relaxed and the workability can be improved, and also the workability at the time of construction at the site can be improved, and the work can be simplified and labor can be saved. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a precast reinforced concrete beam of the present invention, showing a structure near an end.

FIG. 2 is a side sectional view showing a structure near an end of the precast reinforced concrete beam.

FIG. 3 is a schematic view showing an example of a joint structure in which a precast reinforced concrete beam and a column are joined according to a method for joining a precast reinforced concrete beam of the present invention.

FIG. 4 is a diagram showing distribution of bending moments acting on precast reinforced concrete beams and columns during an earthquake or the like in the joint structure of FIG. 3;

FIG. 5 is a diagram schematically showing the exchange of force between a precast reinforced concrete beam and a joining steel material.

FIG. 6 is a plan view showing another example of a joint structure in which a precast reinforced concrete beam and a column are joined according to the method of joining a precast reinforced concrete beam of the present invention.

FIG. 7 is a side view showing the joint structure.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 PC beam (precast reinforced concrete beam) 1a Joining end face 7 Anchor bar 8 Joining steel 12 Column (other members) 16 PC beam (Precast reinforced concrete beam) 16a Joining end face 17 Jointing steel 18 Column (other members)

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinji Kota 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation (56) References JP-A-52-152611 (JP, A) 5-49927 (JP, U) JP-A-58-47616 (JP, U) Patent 2949650 (JP, B2) Patent 2560912 (JP, B2) JP 6-99963 (JP, B2) JP JP 63-11504 (JP, B2) JP-B 53-25408 (JP, B2) JP 6-34498 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) E04C 3/20 E04B 1 / 21 E04B 1/30

Claims (2)

(57) [Claims] 1. A precast reinforced concrete beam characterized in that a joining steel material is movably embedded so as to protrude from a joint end face and to adjust its projecting dimension. 2. When a precast reinforced concrete beam in which a joining steel material is movably buried is constructed so that the joining steel material can be adjusted in a projecting state from the joint end face and the projecting dimension thereof can be adjusted, the projecting dimension of the joining steel material is adjusted. A method for joining precast reinforced concrete beams, wherein the joining steel material is joined to another member while adjusting, and then the joining steel material is fixed to anchor bars prearranged in the precast reinforced concrete beam.