JPH0238648A - Precast concrete beam - Google Patents

Abstract

PURPOSE:To obtain precast concrete beams for enabling main reinforcing bars to be connected certainly and easily by arranging recessed sections extended from end surfaces to an internal side by proper lengths, to set end sections to be the sections of U-shaped cross-sectional areas, and by projecting the end sections of the embedded main reinforcing bars into the recessed sections. CONSTITUTION:Recessed sections 2 extended from end surfaces to an internal side by proper lengths are arranged, and end sections are set to be the sections of U-shaped cross-sectional areas, and into the recessed sections 2, the end sections of embedded main reinforcing bars 3 are projected, and precast concrete beams 1 are formed. Then, the main reinforcing bars 3 of the beams 1 confronted with each other to be erected on a column 5 can be connected to each other securely and easily, and the work of filling up a connecting section 6 with concrete can be also certainly executed.

Description

[Detailed description of the invention] (Technical field to which the invention belongs) The present invention relates to a beam made of precast concrete.

(Problems to be solved by the invention and its features) A recess with a U-shaped cross section extending inward from the end face for an appropriate length is provided at the end, and a splice reinforcement for joining or a main reinforcement at the lower end is disposed within the recess. A precast concrete beam connected to a column is known from Japanese Patent Application Laid-Open No. 59-118939.
(See Japanese Patent Application Laid-open No. 60-95046).

An object of the present invention is to provide a precast concrete beam that can easily connect the buried main reinforcing bars of opposing beams at the joint with a column or in a recess of the beam to form a through reinforcement. The structural features thereof are as described in the claims.

(Example) In FIGS. 1 and 2, a recess 2 is provided at the end of a precast concrete beam 1 (hereinafter simply referred to as beam 1) and extends inward from the end surface by an appropriate length. , beam 1
The end of the main reinforcing bar 3 buried below is protruding. In the case of the figure, there are four main reinforcing bars 3, all of which extend slightly further forward from the end face of the beam 1.

In addition, in the figure, 4 is a rib muscle.

Although the main reinforcing bars 3 in this embodiment are in one stage, they may be in two stages, and in this case, the ends of the main reinforcing bars in both stages are made to protrude into the recess 2.

Further, the protrusion length of the main reinforcing bar 3 is arbitrary, and it may be extended further forward than in the case shown in the figure, or conversely, may be made to protrude short into the inner part of the recess 2.

When constructing the illustrated beams 1, as shown in FIG. The corresponding main reinforcing bars 3 of each opposing beam 1.1 are connected by welding via joint reinforcements 7 at the joint 6, and all the main reinforcing bars 3 are connected in the same way to form a through reinforcement. Recess 2 and joint 6
Place concrete. At this time, the reinforcing bars are also arranged inside the recess 2, but although the reinforcing bars inside the recess 2 are not shown, they are kept deep inside the recess 2 until the connection of the main reinforcing bars of the beam 1 described above is completed. . In addition, in the figure, 8 is the axial reinforcement of the column 5.

The case in Fig. 4 corresponds to the case where the protruding length of the main reinforcing bar 3 of one of the opposing beams 1.1 in Fig. 3 is lengthened by the length of the joint bar 7; The reinforcing bars 3 can be directly connected to each other at the joint portion 6 without using a connecting bar.

The case where the main reinforcing bars 3 are connected at the joint 6 has been described above, but according to the present invention, the main reinforcing bars 3 can be connected to each other within the recess 2 by adjusting the protruding length of the main reinforcing bars 3. You can also do it.

Next, the construction of a beam when the main reinforcing bars are in two stages will be explained.

In the case of Figures 5 to 7, the lower main reinforcing bars 1 and the upper main reinforcing bars 1O of the opposing beams 1 and 1 are both located forward from the end face of each beam, similar to the main reinforcing bars 3 in Fig. 3. The corresponding main reinforcing bars 9 and IO are connected to each other through connecting bars 11 and 12 at the joints 6 above the columns 5, respectively.

In the case of FIGS. 8 to 10, the main reinforcing bar 9 at the lower stage of one of the opposing beams 1 and 1 protrudes long enough to enter the recess 2 of the other beam 1, and The main reinforcing bar 9 is in its recess 2
The main reinforcing bars 9 are connected to each other by the other beam 1.
The main reinforcing bars 10 on the upper stage of the beams 1.1 protrude shortly into the depths of the recesses 2 of each beam 1, and the main reinforcing bars 10 are connected to each other. The connection is made via long joints 13, the welds of which are located in each recess 2.

Although not shown, the connections between the main reinforcing bars in the lower stage and the main reinforcing bars in the upper stage are the same as the connections of the main reinforcing bars in Figures 4 and 3, respectively, and both are the same as in Figures 8-1θ. The connection may be made in the same way as the connection of the main reinforcing bars in the upper row.

In the case of this two-stage reinforcement arrangement, if the main reinforcing bar in the upper stage is lengthened,
When constructing intersecting beams, this will hit the main reinforcing bars at the bottom, so
It is important to pay attention to this point. As for the connection order, it is preferable to start connecting the upper main reinforcing bars after all of the lower main reinforcing bars have been connected.

(Effects of the Invention) Since the precast concrete beam of the present invention is as described above, when the precast concrete beam is erected, the main reinforcing bars buried under the beams facing each other on the column can be reliably connected to each other to form a strong joint. Furthermore, by appropriately selecting the protruding length of the main reinforcing bars, the connection work between the main reinforcing bars can be performed not only on the columns but also in recesses, and it is also possible to perform two-stage reinforcement arrangement. It is extremely easy to handle reinforcing bars when erecting beams in two orthogonal directions, and it has the effect of preventing "C" reinforcing bars from crowding at joints and causing poor concrete filling properties. You can expect it.4

[Brief explanation of the drawing]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2A is an enlarged sectional view taken along the line A-A in Fig. 1, the opening of the figure is an enlarged sectional view taken along the line B-B, and Fig. 3 is an enlarged sectional view taken along the line B-B of Fig. 1. An example of construction Ra! An explanatory plan view, FIG. 4 is the same as the above, FIG. 5, and FIG.
The figure is a plan view for explaining the construction mode of another modified example (two-stage reinforcement arrangement) of the present invention, FIG. 7 is a sectional view, and FIGS. The plan view for explaining the construction mode of the reinforcement (reinforcement arrangement) and FIG. 10 are also sectional views. 1: Precast concrete beam (beam), 2: Recess, 3
: Main reinforcing bar, 5: Concrete column (column), 6: Joint, Patent applicant: Fudo Construction Co., Ltd. Patent attorney Hiroshi Someya (deceased) Figure 1 Figure 2 (deceased) Figure 10

Claims (1)

[Claims] A precast concrete beam characterized in that a recess having a U-shaped cross section extending inward from the end face for an appropriate length is provided at the end, and the end of a buried main reinforcing bar projects into the recess.