JP5027830B2 - Beam structure and method for constructing beam structure - Google Patents

Description

  The present invention relates to a beam structure using a PCa member and a method for constructing the beam structure.

  Patent Documents 1 and 2 disclose beam structures using PCa members (precast concrete members).

  The beam structure disclosed in Patent Document 1 is a beam structure on the premise that the lower main bar (lower beam main bar) of the PCa member for a small beam is not fixed to the main beam, and is a side surface of the PCa member for the main beam. The PCa member for the small beam is placed in the notch formed by cutting the beam to the inside of the main beam of the beam, and after closing the gap between the side surface of the PCa member for the large beam and the end surface of the PCa member for the small beam with grout Concrete is placed on the PCa member.

  The beam structure disclosed in Patent Document 2 is a beam structure on the premise that the lower main bar of the small beam PCa member is fixed to the large beam, and is small at a position greatly separated from the side surface of the large beam PCa member. When placing the PCa member for beams and placing concrete on both PCa members, the concrete is also placed between the side surface of the PCa member for large beams and the end surface of the PCa member for small beams. is there.

  Patent Document 2 discloses a beam structure on the premise that the lower main bar of the PCa member for a small beam is fixed to the large beam as a prior art of the beam structure described above, and the side surface of the PCa member for the large beam is shown. When the PCa member for small beam is placed on the side edge of the notch that is formed to be deeply cut into the inside of the main bar, and the concrete is placed on both PCa members, the concrete is also applied to the notch. A beam structure that is installed is disclosed.

JP-A-5-179700 JP-A-6-42039

  In the beam structure of Patent Document 1, since the grout filling process takes time, there is a risk that the construction period will be prolonged, and the cost of materials will increase due to the use of expensive grout. In addition, in the beam structure of Patent Document 1, when manufacturing a PCa member for a large beam, a formwork (unboxing) for forming a notch portion is required, but the notch portion is a main bar of the PCa member for a large beam. There is also a problem that the installation / demolding work of the mold becomes complicated. In addition, since the beam structure of patent document 1 makes the grout filling to the clearance gap between the PCa member for large beams and the PCa member for small beams essential composition requirements, a grout filling process cannot be omitted.

  In the beam structure of Patent Document 2, although the grout filling process is not required, the small beam PCa member is not placed on the large beam PCa member, so a large-scale support is required to support the small beam PCa member. become. Further, in the beam structure of Patent Document 2, it is necessary to cast cast-in-place concrete at the joint portion (end portion of the small beam) between the large beam and the small beam. Since the PCa member is far away from the PCa member, a frame support work is required when constructing the joint portion. As described above, the beam structure of Patent Document 2 requires a great amount of time and labor for installation / disassembly work such as formwork support work, so that the merit of using the PCa member is impaired.

  In the technique introduced as the prior art of the beam structure of Patent Document 2, it is necessary to fix the lower main bar of the PCa member for the small beam to the main beam. It is necessary to greatly lack up to. In order to produce a PCa member for a large beam having such a shape, it is necessary to prepare a formwork for a notch portion. However, it is possible to install / remove while avoiding the main bars and stirrups arranged in the PCa member for a large beam. Since it is necessary to mold, it takes time and effort.

  From such a point of view, the present invention provides a beam structure that can shorten the work period and can reduce labor and cost required for manufacturing a PCa member for a large beam, and a method for constructing the beam structure. Is an issue.

A beam structure according to the present invention that solves such a problem is provided on a large beam formed by placing cast-in-place concrete on a large beam PCa member including a reinforcing bar to be a stirrup, and on a small beam PCa member. A beam structure comprising a cast-in-place concrete beam, wherein the PCa member for the large beam has a support surface formed on the covered concrete portion outside the stirrup. The support surface is located below the upper surface of the main body concrete portion of the large beam PCa member, and the small beam PCa member is connected to the large beam PCa member from the lower end of the longitudinal end surface thereof. An overhanging portion projecting toward the support surface, and the overhanging portion is mounted on the support surface, and the side surface shape of the overhanging portion has a tapered trapezoidal shape. The top surface is inclined downward Both the located at lower than the upper surface of the main body concrete portion of the girders for PCa member, the upper surface of the main body concrete portion of the joists for PCa member, the upper surface of the main body concrete portion of the girders for PCa member It is located at a high place, and the concrete cast on the large beam PCa member and the small beam PCa member is also filled in the space above the overhanging portion.

  According to the present invention, the work of filling grout becomes unnecessary, and the support work for supporting the PCa member for a small beam can be omitted or simplified, so that the work period can be shortened. Moreover, when molding the support surface of the PCa member for the large beam, it is only necessary to cut out only the covering concrete part that does not easily interfere with the reinforcing bar, so that the installation and demolding work of the mold for molding the support surface is not necessary. It becomes easy. In the present invention, the side surface of the PCa member for the large beam and the end surface of the PCa member for the small beam are not greatly separated from each other. A small one is acceptable.

  When the projecting portion of the PCa member for the small beam is placed on the support surface of the PCa member for the large beam, a gap is formed between the side surface of the main body concrete portion of the PCa member for the large beam and the end surface of the PCa member for the small beam. However, if the upper surface of the main body concrete part of the PCa member for small beams is positioned higher than the upper surface of the main body concrete part of the PCa member for large beams, compared to the case where they are arranged so as to be flush with each other. Since the gap becomes shallow, it becomes easy to fill the gap with concrete.

  A rib extending upward from the upper surface of the protruding portion may be provided on the end face in the longitudinal direction of the PCa member for the small beam. In this way, the overhanging portion is reinforced and irregularities are formed on the end face of the small beam PCa member, so that the cast-in-place concrete and the small beam PCa member are firmly bonded. Become.

  According to the present invention, it is possible to shorten the work period, and further, it is possible to reduce the labor and cost required for manufacturing the PCa member for large beams.

It is a sectional side view which shows embodiment of the beam structure which concerns on this invention. It is a perspective view which shows the PCa member for large beams, and the PCa member for small beams. (A)-(c) is a sectional side view for demonstrating the construction method of the beam structure shown in FIG. It is a top view which shows the junction part of the PCa member for large beams, and the PCa member for small beams.

  As shown in FIG. 1, a beam structure B according to an embodiment of the present invention includes a large beam 1 supported by a pillar (not shown), and small beams 2 and 2 joined to the side surface of the large beam 1. ing.

  The girder 1 is constructed by placing cast-in-place concrete on the girder PCa member 10, and is formed of the lower concrete portion 1 </ b> A corresponding to the concrete portion of the girder PCa member 10 and cast-in-place concrete. And an upper concrete portion 1B. The lower main bar (lower beam main bar) 1a of the main beam 1 is arranged in the lower concrete part 1A, and the upper main bar (upper beam main bar) 1b is arranged in the upper concrete part 1B.

  The PCa member 10 for a large beam is a precast concrete member including a lower main reinforcing bar 1a of the large beam 1 and a reinforcing bar 1c to be a stirrup, and can withstand a load at the time of construction that acts until the upper concrete portion 1B is cured. Has cross-sectional performance. As shown in FIG. 2, the PCa member 10 for large beams of this embodiment includes a main body concrete portion 11 surrounded by a reinforcing bar (star wrap) 1c, a covered concrete portion 12 outside the reinforcing bar 1c, and a main body concrete portion 11. The lower main reinforcing bar 1a and the reinforcing bar 1c are arranged.

  In the present embodiment, the covered concrete portions 12 and 12 on both sides of the main body concrete portion 11 are protruded upward from the upper surface of the main body concrete portion 11, but the cross-sectional shape of the large beam PCa member 10 is limited. Absent. Incidentally, the height position of the upper end surface of the covered concrete portion 12 is matched with the height position of the lower surface of the adjacent slab (not shown), and the slab PCa member (not shown) is placed on the upper end surface of the covered concrete portion 12. ) Is placed.

  The covering concrete portion 12 is formed with a support surface 13 for supporting the small beam PCa member 20.

  The support surface 13 is formed by notching only the covered concrete portion 12, and is located at a position one level lower than the upper surface of the main body concrete portion 11. The width dimension of the support surface 13 is substantially the same as the cover thickness of the reinforcing bar 1c, and the depth dimension of the support surface 13 (the dimension in the longitudinal direction of the PCa member 10 for the large beam) is appropriate for the width dimension of the PCa member 20 for the small beam. It is the size that added a certain clearance. In addition, the support surface 13 is formed by extracting a part of the upper part of the covering concrete part 12 in a rectangular shape at the time of manufacturing the PCa member 10 for a large beam.

  As shown in FIG. 1, the small beam 2 is formed by placing cast-in-place concrete on the small beam PCa member 20, and corresponds to the concrete portion of the small beam PCa member 20. 2A and an upper layer concrete portion 2B made of cast-in-place concrete.

  The lower main reinforcement 2a of the small beam 2 is arranged in the lower concrete section 2A, and the upper main reinforcement 2b is arranged in the upper concrete section 2B. The lower main reinforcement 2a is bent up at the end of the lower concrete portion 2A (the small beam PCa member 20). That is, the lower main reinforcement 2a is arranged only in the lower concrete portion 2A (the small beam PCa member 20), and does not protrude from the end surface of the lower concrete portion 2A. On the other hand, the upper main reinforcement 2b protrudes from the end surface of the upper concrete portion 2B and is fixed to the girder 2.

  The PCa member 20 for a small beam is a precast concrete member including a lower main bar 2a of the small beam 2 and a reinforcing bar 2c to be a stirrup, and can withstand a load applied during construction until the upper concrete portion 2B is hardened. It has such cross-sectional performance.

  As shown in FIG. 2, the PCa member 20 for a small beam of the present embodiment includes a main body concrete portion 21 surrounded by an outermost reinforcing bar (star wrap) 2c, and a covered concrete portion outside the outermost peripheral reinforcing bar 2c. 22, an overhang portion 23 and ribs 24, 24 formed on the end face in the longitudinal direction, and a lower main reinforcing bar 2 a and a reinforcing bar 2 c arranged in the main body concrete portion 21.

  The upper surface of the main body concrete portion 21 is located higher than the upper surface of the main body concrete portion 11 of the large beam PCa member 10 (see FIG. 1). Incidentally, the upper end surface of the covered concrete portion 22 is located at the same height as the lower surface of the adjacent slab (not shown), and the slab PCa member (not shown) is placed on the upper end surface of the covered concrete portion 22. Placed.

  The projecting portion 23 is a portion projecting from the lower end portion of the longitudinal end surface of the small beam PCa member 20 toward the large beam PCa member 10. It is continuous in the direction. The side surface shape of the overhang portion 23 has a tapered trapezoidal shape, and the upper surface of the overhang portion 23 is inclined downward. Further, the lower surface of the overhang portion 23 is flush with the lower surface of the main body concrete portion 21.

  The rib 24 extends upward from the upper surface of the overhang portion 23. The planar shape of the rib 24 has a tapered trapezoidal shape. In the present embodiment, the pair of ribs 24, 24 are arranged side by side in the width direction of the PCa member 20 for small beams. However, the number and position of the ribs 24 are not intended to be limited.

  Although the overhang | projection part 23 and the rib 24 of this embodiment consist of concrete and are integrally molded with the main body concrete part 21 and the covering concrete 22, the overhang | projection part is utilized using the steel material etc. which were embedded in the main body concrete part 23 grade | etc.,. 23 and ribs 24 may be formed.

Next, with reference to FIG. 3, the construction method of the beam structure B will be described in detail. In addition, in FIG. 3, illustration of the reinforcement embed | buried in concrete is abbreviate | omitted suitably.
First, the PCa member 10 for large beams is placed on a pillar (not shown) and the like, and thereafter, as shown in FIG. The overhanging portion 23 of the beam PCa member 20 is placed. The large beam PCa member 10 and the small beam PCa member 20 may be supported by a small support.

  Subsequently, as shown in FIG. 3B, the upper main bar 1b of the large beam 1 and the reinforcing bar 1d to be a stirrup are assembled to the reinforcing bar 1c protruding from the large beam PCa member 10, and the small beam PCa member is assembled. The upper main reinforcing bar 2b of the small beam 2 and the reinforcing bar (not shown) to be the stirrup are assembled to the reinforcing bar (star wrap) 2c protruding from 20.

  In addition, although illustration is abbreviate | omitted, in the area | region which installs the formwork for shape | molding upper-layer concrete part 1B, 2B (refer FIG. 1) and adjoins the PCa member 10 for large beams, and the PCa member 20 for small beams, it is required. Accordingly, a PCa member for slab (not shown) or a slab formwork is arranged, and a slab reinforcement (not shown) is arranged.

  FIG. 4 is a view of the large beam PCa member 10 and the small beam PCa member 20 combined in the state shown in FIG. 3A as viewed from the upper surface side. As shown in FIG. 10 and the small beam PCa member 20 are disposed with a leakage preventing member 3 that closes the gap between the large beam PCa member 10 and the small beam PCa member 20. The leakage preventing member 3 is arranged from the same height position as the support surface 13 (see FIG. 2) to the height position of the upper end surface of the covered concrete portion 12 of the large beam PCa member 10, and the side surface of the large beam PCa member 10. And the side surface of the PCa member 20 for a small beam. Although there is no restriction | limiting in the form of the leak-proof member 3, In this embodiment, it comprises with the profile (an angle steel) which exhibits L shape.

  When the work for placing the formwork and the placement work are completed, concrete is placed on the PCa member 10 for the large beam and the PCa member 20 for the small beam, as shown in FIG. The concrete placed on the large beam PCa member 10 is a gap D (see FIG. 3 (FIG. 3) formed between the side surface of the main body concrete portion 11 of the large beam PCa member 10 and the end surface of the small beam PCa member 20. b) and the ribs 24, and finally the concrete is filled in the space above the overhanging portion 23 of the PCa member 20 for a small beam. That is, the cast-in-place concrete is filled between the end faces of the left and right small beam PCa members 20 and 20.

  When the concrete is hardened, a beam structure B in which the upper concrete portion 1B of the large beam 1 and the upper concrete portion 2B of the small beam 2 are integrally formed is formed.

  According to the beam structure B according to the present embodiment described above, the grout filling process for filling the gap between the large beam PCa member 10 and the small beam PCa member 20 is not required, and the small beam PCa member 20 is supported. Since the support work can be omitted or simplified, the work period can be shortened.

  Further, when forming the support surface 13 of the PCa member 10 for large beams, it is only necessary to cut out only the covering concrete portion 12 that is unlikely to interfere with the reinforcing bar 1c, so that a formwork for forming the support surface 13 is installed.・ Demolding work becomes easy.

  In the beam structure B of the present embodiment, since the protruding portion 23 of the PCa member 20 for the small beam is placed on the PCa member 10 for the large beam, the side surface of the PCa member 10 for the large beam and the PCa member 20 for the small beam Compared to a case where the end surfaces are not greatly separated from each other and the both are largely separated from each other, the mold (leakage-preventing member 3) installed around the abutting portion of both the PCa members 10 and 20 is simple and small-scale. become.

  In the beam structure B of the present embodiment, the upper surface of the main body concrete portion 21 of the PCa member 20 for small beams is positioned higher than the upper surface of the main body concrete portion 11 of the PCa member 10 for large beams. The gap D becomes shallower than the case where the gaps are arranged to be uniform, and as a result, the gap D is easily filled with concrete.

  In this embodiment, since the overhanging portion 23 of the PCa member 20 for small beams is reinforced by the ribs 24, 24, damage to the overhanging portion 23 at the time of transporting / loading the PCa member 20 for small beams is prevented. Can do. Further, since the ribs 24 and 24 are provided, irregularities are formed on the end face of the small beam PCa member 20, so that the concrete and the small beam PCa member placed on the large beam PCa member 10 are provided. 20 end surfaces mesh with each other, and both are firmly joined.

  In this embodiment, the small beam PCa members 20 and 20 are arranged on both sides of the large beam PCa member 10 and the large beam 1 and a pair of small beams 2 and 2 opposed to each other are constructed at the same time. Although illustrated, of course, the PCa member 20 for the small beam may be disposed only on one side of the PCa member 10 for the large beam.

B Beam structure 1 Large beam 10 PCa member for large beam 11 Main body concrete part 12 Covered concrete part 13 Support surface 1c Rebar (Stirrup)
2 Small beam 20 Small beam PCa member 21 Main body concrete part 23 Overhang part 24 Rib

Claims (2)

A girder constructed by placing cast-in-place concrete on a PCa member for girder including reinforcing bars to be stirrup,
A beam structure comprising: a small beam configured by placing cast-in-place concrete on a PCa member for a small beam,
The large beam PCa member has a support surface formed on the covered concrete portion outside the stirrup,
The support surface is located below the upper surface of the main body concrete portion of the PCa member for the large beam,
The small beam PCa member has an overhanging portion that projects from the lower end of the longitudinal end surface toward the large beam PCa member,
The overhanging portion is placed on the support surface,
The side surface shape of the overhanging portion has a tapered trapezoidal shape,
The upper surface of the overhanging portion is inclined downward and is positioned lower than the upper surface of the main body concrete portion of the PCA member for the large beam,
The upper surface of the main body concrete part of the PCa member for small beams is located higher than the upper surface of the main body concrete part of the PCa member for large beams,
A beam structure in which concrete cast on the PCa member for the large beam and the PCa member for the small beam is also filled in a space above the projecting portion.   2. The beam structure according to claim 1, wherein a rib extending upward from an upper surface of the projecting portion is provided on an end face in a longitudinal direction of the PCa member for the small beam.

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