JPH07279428A - Constructing method of continuous frame by prestressed reinforced concrete construction - Google Patents

Abstract

PURPOSE:To solve trouble on processes until strength is displayed at a time when a method of post-tensioning construction is applied while omitting cost required for a grouting. CONSTITUTION:Half PCa beams 2 formed in U-shaped cross sections are arranged continuously among a plurality of columns 1, the half PCa beams are joined mutually by primary concrete or a joining means such as the welding of steel sheets in zones surrounded by the columns 1 and panels 1a, and PC steel wires 6 are disposed in the cavity sections of the half PCa beams 2 and stretched. Concrete is placed in the cavity sections.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a continuous prestressed reinforced concrete frame composed of half precast concrete (hereinafter referred to as half PCa).

[0002]

2. Description of the Related Art In a prestressed reinforced concrete structure, a sheath pipe for PC (prestressed reinforced concrete) is generally piped to pour concrete at the time of assembling the rebar, and after the strength of the concrete is manifested, a PC steel wire is inserted into the sheath pipe for tensioning, There are a post-tensioning method for fixing and grout, and an unbonded PC method that does not require grout instead of a PC sheath.

All of these have an advantage that a frame with a large span is easy because the tensile resistance of a member, such as a beam, to which tensile stress is easily applied increases, and the bending resistance increases.

[0004]

However, when the former construction method is applied to the construction of a continuous frame-column structure, tension work is started after waiting for the strength of the concrete forming the beam to start. There was a problem that the grout cost was increased.

When the latter unbonded PC construction method is applied to a frame, the adhesive force between PC steel wire and concrete is essentially weak, so that it is difficult to use it for a main member such as a girder that bears an earthquake force. Therefore, the application was limited.

The present invention has been made in view of the above-mentioned drawbacks, and an object thereof is to solve the process problem until the strength is exerted when the post-tensioning method is applied and to reduce the cost for grout. The present invention provides a method for constructing a continuous frame made of PC concrete that is made possible.

Another object of the present invention is a half PCa.
The purpose is to enable the PC steel wire to be tensioned and anchored directly to the tensioned and anchored ends of the beam.

Still another object of the present invention is to enable the introduction prestressing force to be transmitted between a plurality of half PCa beams which are continuous with a column interposed therebetween.

Still another object of the present invention is to ensure the accurate height of the PC steel wire to be placed in the half PCa.

[0010]

In order to achieve the above-mentioned object, the present invention is to dispose a half PCa beam having a U-shaped cross section continuously between a plurality of columns, and to form the half P in a column panel zone.
After joining the Ca beams to each other by a joining means, a PC steel wire is placed in the hollow portion of the half PCa beam and tensioned, and then concrete is placed in the hollow portion.

Further, according to the present invention, only the portions of the half PCa beam at the tension end and the fixing end can be a full precast beam in which a sheath into which the PC steel wire is inserted and a cone or casting is driven.

Further, according to the present invention, the joining means places primary concrete at a position lower than the height at which the PC steel wire is arranged in the column panel zone where the half PCa beams intersect, and then the PC steel wire is arranged. However, the prestressing force can be transmitted between the half PCa beams.

Further, instead of the operation of placing the primary concrete, it is also possible to join the steel plates punched at the ends of the half PCa beams by welding.

Further, according to the present invention, a supporting means for holding the PC steel wire at a predetermined height position is provided inside the cavity of the half PCa beam along the insertion direction of the PC steel wire. Can also be adopted.

[0015]

In the method of the present invention having the above construction, each half PCa beam itself connected to the column supports the prestressing force introduced into the PC steel wire, and the concrete is then cast into the cavity to fix the PC steel wire. Together with, the continuous frame is completed (Claim 1).

When the construction of claim 2 is adopted, the tension and fixing of the PC steel wire can be carried out by a general PC construction method.

According to the third and fourth aspects, after the fixing of each half PCa to the pillar, the PC steel wire can be wired in the plurality of continuous half PCa by sandwiching the pillar without any trouble. Deformation between columns and beams after the introduction of prestress is also prevented.

In the case of the fifth aspect, the accurate height of the PC steel wire in each half PCa can be secured, and the vertical force generated with the tension of the PC steel wire can be transmitted to the half PCa beam.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below step by step.

FIGS. 1 (a) to 1 (c) show a construction procedure of the method of the present invention. First, in FIG. 1 (a), each half PCa beam 2 according to the present invention is formed in a cross shape on an upper portion of each pillar 1. The ends are installed in the panel 1a provided on the upper part of the pillar 1 so as to cross each other.

Each half PCa beam 2 is shown in FIG. 2 and FIG.
As shown in (a) and (b), the beam main reinforcement 2a and a large number of U-shaped stirrup reinforcements 2b arranged orthogonal to the main reinforcement 2a are molded in a U-shaped cross section in a state where they are integrally embedded. It is composed of PCa beam skeleton 3, and inside the cavity of beam skeleton 3, a pair of T-shaped holding hardwares 4 and 5 having different heights whose lower end and both ends are joined to beam skeleton 3 are arranged at predetermined intervals. .

Each of the holding hardwares 4 and 5 is obtained by integrally welding sheath short pipes 4a and 5a on the upper part thereof, and by passing the PC steel wire 6 through each of the sheath short pipes 4a and 5a and tensioning the sheath short pipes 4a and 5a, The height of the PC steel wire 6 is accurately maintained.

The tension and fixing portions of the PC steel wire 6 at the end of the continuous frame composed of the half PCa beams 2 shown on both sides of FIG. 1 (c) are as shown in FIGS. It is a full precast filling structure that rises diagonally from the hollow portion of the skeleton 3, and a pair of funnel-shaped sheaths 3b are opened from this fixing portion 3a toward the end face, and the end portion of each PC steel wire 6 is formed in this. Through insertion, the wedge 7 is used for tension fixing at the end surface of the fixing portion 3a.

An air vent hole 3c communicating with the sheath 3b is opened on the end face so that fluid concrete is filled in the sheath 3b in the concrete pouring step to be described later so that the grout effect is exerted. ing.

After the half PCa beams 2 have been erected, a slab form 8 such as a plywood form or a deck plate or a PC plate is placed in a plane surrounded by the half PCa beams 2 as shown in FIG. 1 (b). It will be laid on one side and a slab will be constructed using the conventional floor formwork method.

At the same time, each half PCa beam 2 is joined to the pillar 1. As this joining method, the introduced prestressing force can be continuously transmitted, for example, as shown in FIG.
As shown in Fig. 1, a primary concrete 9 made of non-shrink fast early concrete is placed below the lower end where the PC steel wire 6 is stretched in the zone surrounded by the pillar 1 and the panel 1a, and the facing half PCa beam 2 As shown in FIG. 6 (b), the steel plate 1 driven into the end of the half PCa beam 2 in the zone surrounded by the pillar 1 and the panel 1 a.
There are two methods of in-situ welding with 0 as a cross beam, and the most appropriate joining method can be selected in the field.

After the above connecting work is completed, as shown in FIG.
As shown in (b) and FIG. 1 (c), the sheath tube 4 of each half-PCa beam 2 that is continuous with each PC steel wire 6 across the column 1.
Wiring is carried out through b and 5b, and both ends thereof are tensioned and fixed by a method adapted to a generally adopted PC construction method, for example, pulled by a jack and stopped by a wedge method to introduce prestress.

By introducing the prestress, the vertical force generated together with the tension of the PC steel wire 6 can be transmitted to each half PCa beam 2 through the holding hardware 4 and 5.

After the pre-stress is introduced, as shown in FIG. 1 (c), the stirrup ribs 2b protruding above the half PCa beams 2 and the upper main ribs 11a of the beams or the slab ribs 1 are formed.
After assembling 1b, cast-in-place concrete C is poured into the cavity and slab of the half PCa beam 2.

By solidifying the concrete C, the beam frame 3
At the same time, the cavity is completely filled and an integrated beam is formed, and at the same time, the PC steel wire 6 is settled by the grout effect of the concrete C, and a continuous frame structure for prestressed reinforced concrete is completed.

In the fixing portion 3a, the air vent hole 3c
The concrete C flowing into the sheath 3b is filled while expelling air through it, and a complete fixing state is achieved.

[0032]

As described above in detail with reference to the embodiments, the half PCa beams themselves connected to the columns support the prestressing force introduced into the PC steel wire, and the concrete is then poured into the cavity to form the PC. Since the continuous frame is completed at the same time as the steel wire is fixed, problems in the process can be solved, and the pouring concrete also serves the function of grout, and the labor of grout injection is omitted, so it can be made cheaper and structurally Also, since the prestressing force can be transmitted continuously without distorting between the multiple beams across the column, the prettress force becomes more uniform than when prestressing is applied to each beam, and the work itself is also simplified. There is an advantage to Therefore, the present invention is suitable as a method for constructing a main part such as a girder that bears seismic force, and also has an advantage that the PC steel wire itself is less likely to rust.

Further, according to the second aspect of the present invention, the tension and fixing of the PC steel wire can be performed by the general PC construction method, and the work can be simplified.

The structure of claims 3 and 4 of the present invention has an advantage that the wiring of the PC steel wire is not hindered and the joint portion of the column and beam is not deformed when the prestress is introduced.

Further, according to the fifth aspect of the present invention, the accurate height of the PC steel wire in each half PCa can be ensured, and the vertical prestressing force generated with the tension of the PC steel wire can be secured. There is an advantage that it can be transmitted to the beam.

[Brief description of drawings]

1A to 1C are explanatory views showing a procedure for constructing a continuous frame according to the present invention.

FIG. 2 is an enlarged perspective view showing a joint portion between a half PCa and a column.

FIG. 3A is a sectional view of the half PCa beam.
(B) is the sectional view on the AA line of (a).

FIG. 4 is an enlarged cross-sectional view of a tension and fixing portion of the half PCa.

FIG. 5 is a perspective view of the same.

FIG. 6A is a partial cross-sectional view showing an example of a method of joining half PCa to a column. (B) It is a partial expanded sectional view showing another example of the joining method.

[Explanation of symbols]

 1 Pillar 1a Panel 2 Half PCa Beam 3 PCa Beam Frame 4,5 Holding Hardware 6 PC Steel Wire 9 Primary Concrete 10 Steel Plate C Concrete

Claims (5)

[Claims] 1. A half precast concrete beam having a U-shaped cross section is continuously arranged between a plurality of columns, and the half precast concrete is joined by a joining means in a column panel zone, and then a PC steel wire is half precast concrete. A method for constructing a continuous frame by prestressed reinforced concrete construction, which comprises arranging in a hollow portion of a beam and tensioning it, and then placing concrete in the hollow portion. 2. A full precast beam in which a sheath and a cone into which the PC steel wire is inserted and a cone or a casting are cast only in the portions of the tensioned end and the anchored end of the half precast concrete beam. A method for constructing a continuous frame by the prestressed reinforced concrete construction described. 3. The joining means comprises a pillar panel zone where the half precast concrete beams intersect with each other,
The primary concrete is placed at a position lower than the height at which the steel wire is arranged, and then the PC steel wire is arranged to transfer a prestressing force between the respective half precast concrete beams. A method for constructing a continuous frame by the prestressed reinforced concrete construction described. 4. The prestressed reinforced concrete construction according to claim 1 or 2, characterized in that, instead of the operation of placing the primary concrete, the steel plates driven into the ends of the half precast concrete beams are joined by welding. How to build a frame. 5. A supporting means for holding the PC steel wire at a predetermined height position along the insertion direction of the PC steel wire is provided inside the cavity of the half precast concrete. The method for constructing a continuous frame by prestressed reinforced concrete construction according to any one of claims 1 to 4.