JPH073940A - Precast beams in steel reinforced concrete structures - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a precast beam in a steel-framed reinforced concrete structure that improves the workability of a steel-framed reinforced concrete frame and saves labor. [Structure] A beam steel frame 1 is provided with a beam lower end main bar 2 and a beam end lateral reinforcing bar 3, and a beam concrete 4 is cast, and at a projecting end part of the beam lower end main bar 2 from the beam concrete end face, A precast beam A in a steel-framed reinforced concrete structure is constructed in which a horizontal bent portion 2a that bypasses and avoids a column steel frame B'at a column-beam joint is bent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast beam in a steel reinforced concrete structure.

[0002]

2. Description of the Related Art In the conventional steel frame reinforced concrete structure,
The steel frame is erected on site, and the reinforcing bars such as columns and beams are arranged.
After that, the formwork is assembled, the supporting work is installed, and the concrete is placed to make the frame. 7 and 8 show an example of the column-beam joint, where a is a beam, b is a column, c is a beam steel frame, d is a beam main bar, e is a beam lateral reinforcing bar, f is a column steel frame, and g is a column. Main reinforcement, h is horizontal reinforcement of column, i is horizontal reinforcement of column-beam joint,
j is a beam main bar welded joint, and k is a high-strength bolted joint between a column steel frame and a beam steel frame.

Further, as shown in FIG. 9, when the beam is precast, the lower main rebar d of the beam a is connected at the beam end, and therefore a part d'of the main rebar is pre-disposed on the column steel frame f. Make a line.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a steel reinforced concrete structure, the arrangement of reinforcing bars, the formwork, and the supporting work occupy a relatively large proportion in the framework manufacturing work. Particularly, the reinforcement of beams and the arrangement of formwork require temporary construction such as scaffolding, and a lot of labor is required due to work at high places. In addition, when all the construction is done with cast-in-place concrete, the beams need to be supported, and the installation period of this support is longer than other supports on the same floor, which is likely to be an obstacle to the work.

Further, in the case of precasting a beam, since the lower end main bar of the beam is connected to the beam end, it is necessary to dispose a part of the beam main bar on the column steel frame in advance. The present invention has been proposed in view of the above problems of the prior art, the object of which is to provide a precast beam in a steel reinforced concrete structure in which the workability of a steel reinforced concrete frame is improved and labor saving is achieved. There is a point to do.

[0006]

In order to achieve the above-mentioned object, a precast beam in a steel-framed reinforced concrete structure according to the present invention has beam main bars and lateral reinforcing bars arranged in a beam steel frame, and beam concrete is placed therein. The projecting end portion of the main beam of the beam from the concrete end face of the beam has a configuration in which a horizontal bent portion that bypasses the column steel frame at the column-beam joint and is detoured is bent.

According to a second aspect of the present invention, the protruding end portion of the main beam of the beam is spliced at the beam end, and the reinforcing bar for retaining the fixing force is arranged.

[0008]

The beam according to the present invention is a semi-precast beam in which beam main bars and lateral reinforcing bars are arranged in the beam steel frame and concrete is cast into the beam, and horizontal bending is applied to the projecting end of the beam main bar from the beam end face. Since the part is bent, the semi-precast beam is arranged so that the horizontal bent part bypasses the column steel frame without interfering with the column steel frame at the column-beam joint, and By joining the beam main bars, it is not necessary to previously provide the beam lower end main bars in the column / beam joint, and the number of welded joints of the beam main bars can be reduced.

At the same time, due to the action of the reinforcing bar arranged in the bent portion of the beam main bar and the concrete, the beam main bar is firmly fixed to the column-beam joint as described later.

[0010]

The present invention will be described below with reference to the illustrated embodiments. 3 and 4 show an embodiment of a precast beam A in a steel-framed reinforced concrete structure according to the present invention, in which a beam steel frame 1 is provided with a beam lower end main bar 2 and a beam end lateral reinforcement bar 3, and a beam concrete 4 is cast, and the end projections of the beam steel frame 1 of the precast beam A are
A through hole 5 and a bolt hole 6 of the joint lateral reinforcement are formed. Further, the beam end projecting portion of the beam lower end main bar 2 is bent to form a horizontal bent portion 2a that bypasses the column in the column-beam joint portion.

FIG. 5 shows the precast beam assembly sequence,
As shown in FIGS. 5A and 5B, the beam steel frame 1 of the precast beam A manufactured at the factory and the column steel frame B ′ of the steel frame column B previously built on site are joined. Among the precast beams which are orthogonal to each other, the precast beam A whose lower end main bar is located above the lower end main bar of the beam orthogonal to the same beam is installed first, and at this time, the horizontal bending portion 2a of the beam lower end bar 2 of the same beam A is installed. Is installed so as to bypass the pillar steel frame B ′ without interfering with the pillar steel frame B ′.

Next, as shown in FIG. 5C, the precast beam A whose lower end main bar is located at the lower end than the lower end main bar of each of the precast beams A is installed in the same manner as described above, and then the beam upper end main bar 7 and the beam end are installed. Lateral reinforcement 3, pillar main reinforcement 8,
The pillar-beam joint horizontal reinforcements 9'are arranged in parallel to the column lateral reinforcements 9, and the reinforcing bars 11 are arranged between the horizontal bending portions 2a of the beam lower-end main reinforcements 2 to form the columns and the beam ends. A slab half-precast board will be installed and concrete will be cast to construct the frame.

In the joint portion of the column / beam steel frame, the flange is joined by welding w, the web is joined by the high-strength bolt 10, and the beam lower end main bar 2 is joined by welding at the beam end. Figure 6
Shows the anchoring mechanism of the beam lower end main bar 2, which is arranged in the bending part of the beam main bar and acts on the reinforcing rebar 11, the tensile force 11 'of the beam lower end bar, the tensile force of the beam lower bar, and the concrete support working on the bending part of the beam main bar. The pressure 13 fixes the main beam bars to the column-beam joints.

[0014]

As described above, according to the present invention, the horizontal end of the precast beam in the steel-reinforced concrete structure is bypassed to the projecting end of the main beam of the beam from the end face of the beam concrete to avoid the column steel frame in the column-beam joint. By bending the bent portion, it is not necessary to previously provide the beam bottom main bar at the column / beam joint as in the conventional case, and the number of welded main bar bars can be reduced, reducing the work on site. To be done.

According to the second aspect of the present invention, the projecting end portion of the main beam of the beam is joined at the beam end, and the reinforcing bar for holding the fixing force is provided, whereby sufficient fixing force is exhibited.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a steel frame reinforced concrete structure using a precast beam according to the present invention.

FIG. 2 is a vertical sectional view of FIG.

FIG. 3 is a plan view showing an embodiment of a precast beam according to the present invention.

FIG. 4 is an elevational view of FIG.

5 (a), (b) and (c) are process diagrams of a steel frame reinforced concrete structure using the precast beam.

FIG. 6 is an explanatory view showing a beam lower end fixing mechanism.

FIG. 7 is a plan sectional view showing an example of a conventional structure.

FIG. 8 is a vertical cross-sectional view of FIG.

FIG. 9 is a plan sectional view showing another example of the conventional structure.

[Explanation of symbols]

 A Precast beam B Steel column B'Column steel 1 Beam steel 2 Beam bottom main bar 2a Horizontal bending part 3 Horizontal reinforcement of beam end 4 Beam concrete 5 Through hole for horizontal reinforcement of joint 6 Bolt hole 7 Beam top main bar 8 Column Main reinforcement 9 Column horizontal reinforcement 9'Column-beam joint horizontal reinforcement 10 High-strength bolt 11 Reinforcement reinforcement 11 'Tensile force acting on reinforcement reinforcement 12 Beam lower end tension reinforcement 13 Concrete bearing pressure

Claims (2)

[Claims] 1. Beam main bars and lateral reinforcing bars are arranged on the beam steel frame, and beam concrete is placed therein, and the column steel frame at the column-beam joint is avoided at the projecting end of the beam main bar from the end face of the beam concrete. A precast beam in a steel-framed reinforced concrete structure, characterized in that a horizontal bend that detours around is bent. 2. The precast beam in a steel reinforced concrete structure according to claim 1, wherein the projecting end portion of the beam main bar is joined at the beam end, and reinforcing bars for retaining anchoring force are arranged.