Frame construction method

Abstract

To provide a technology capable of enabling efficient introduction of tension to a beam in a tension introduction step, while also enabling a beam to be manufactured as a precast beam component in a component manufacturing step to shorten a construction period of a skeleton construction step, in a frame construction method in which a prestressed beam of RC-construction is stretched between a pair of girders of RC-construction.SOLUTION: A frame construction method comprises: a component manufacturing step in which a girder portion 1A that is a part of the girder 1 in a girder length direction Y to which a beam 2 is connected and the beam 2 are manufactured as an integrated precast beam component 3; a tension introduction step in which tension is introduced to a PC steel from a beam side surface 1f of the girder portion 1A that is an end face in a material axis direction X of the precast beam component 3, to apply prestress to the beam 2; and a skeleton construction step in which the precast beam component 3 is installed at a skeleton construction location to construct the girder 1 and the beam 2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for constructing a structure in which prestressed RC (reinforced concrete) small beams are installed between a pair of large RC beams.

Background Art

[0002] As such a structure, by adopting prestressed small beams as RC small beams installed between a pair of large RC beams, it is possible to suitably cope with cases where the installation interval of the large beams becomes wide. When constructing such a structure in a building construction process at a building construction site, in order to construct prestressed small beams, it is necessary to wait for the concrete to harden after placing the concrete and then apply prestress. However, this will delay the timing of starting the construction of the large beams to which the small beams are connected, and there is a problem that the building construction process is prolonged. Therefore, it has been proposed to shorten the construction period of the building construction process by manufacturing small beams in advance as precast beam members made of precast concrete at a manufacturing site or the like (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the construction method of the structure as described above, it is conceivable to perform a member manufacturing process of manufacturing small beams as precast beam members, a tension introduction process of introducing tensile force into the small beams from the end surface in the material axis direction of the precast beam members, and a building construction process of installing the precast beam members at the building construction site of the construction site and constructing the large beams and small beams. However, in this case, since the end face in the material axis direction of the precast beam member manufactured in the member manufacturing process becomes the end face of the secondary beam itself that is connected to the beam side face of the main beam, a large number of main reinforcing bars with a relatively large diameter for connecting to the main beam will project. Therefore, in the tension force introduction process, there is a problem that a large number of main reinforcing bars protruding from the end face of the precast beam member get in the way and the work of introducing the tension force cannot be efficiently performed.

[0005] In view of this actual situation, the main problem of the present invention is to provide a construction method for a structure in which a prestressed RC secondary beam is installed between a pair of RC main beams. While being able to shorten the construction period of the building construction process by manufacturing the secondary beam as a precast beam member in the member manufacturing process, it is to provide a technology that can efficiently perform the work of introducing tension force to the secondary beam in the tension force introduction process.

Means for Solving the Problems

[0006] The first characteristic configuration of the present invention is a construction method for a structure in which a prestressed RC secondary beam is installed between a pair of RC main beams, a member manufacturing process of manufacturing a part of the main beam in the main beam length direction where the secondary beam is connected to the main beam and the secondary beam as an integral precast beam member made of precast concrete, a tension force introduction process of introducing a tension force to PC steel materials from the beam side face of the main beam part which is the end face in the material axis direction of the precast beam member to apply prestress to the secondary beam, and a building construction process of installing the precast beam member at the building construction location to construct the main beam and the secondary beam.

[0007] According to this configuration, the end face in the material axis direction of the precast beam member manufactured in the member manufacturing process becomes the beam side face (the beam side face opposite to the secondary beams in the large beam portion) of the large beam portion that is a part of the beam length direction where the secondary beams in the large beam are connected. In the large beam portion, although the main reinforcement bars of the secondary beams are fixed inside, those main reinforcement bars of the secondary beams do not penetrate the large beam portion and protrude to the opposite beam side face. Therefore, in the tension introduction process, it is possible to introduce tension using a tension jack or the like from the beam side face of the large beam portion with good workability without being obstructed by the main reinforcement bars of the secondary beams. Therefore, while it is possible to manufacture the secondary beams as precast beam members in the member manufacturing process to shorten the construction period of the building structure construction process, the work of introducing tension to the secondary beams can also be efficiently performed in the tension introduction process.

[0008] The second characteristic configuration of the present invention is that in the building structure construction process, the large beam portions of a plurality of the precast beam members are placed on the previously installed bottom formwork for the large beam with a space therebetween. In the space between the large beam portions of the adjacent precast beam members on the bottom formwork for the large beam, concrete is placed.

[0009] According to this configuration, by placing concrete in the space between the large beam portions of the adjacent precast beam members on the bottom formwork for the large beam, while constructing the secondary beams in the portions other than the large beam portions of the precast beam members, the large beam can be constructed by the large beam portions of the adjacent precast beam members and the concrete placement portion connecting them.

[0010] The third characteristic configuration of the present invention is that in the member manufacturing process, the large beam portions of the pair of large beams and the secondary beams are manufactured as an integral precast beam member. In the building structure construction process, the precast beam member is spanned between a pair of previously installed bottom formworks for the large beam with the large beam portions at both ends of the precast beam member placed.

[0011] According to this configuration, in the frame construction process, by spanning the precast beam member between a pair of bottom formworks for the main girders, it is possible to save or reduce the shoring work directly below the secondary beams, thereby achieving labor saving in the work, and at the same time, a large space can be secured directly below the secondary beams and effectively utilized as a rest area, a material storage area, etc.

[0012] The fourth characteristic configuration of the present invention is a method for constructing a structure according to claim 1 or 2, wherein in the member manufacturing process, a connected member into which slab bars can be inserted and connected is embedded in the beam side surface of the main girder portion of the precast beam member.

[0013] According to this configuration, in the member manufacturing process, since a connected member into which slab bars can be inserted and connected is embedded in the beam side surface of the main girder portion of the precast beam member, it becomes possible to insert and connect the slab bars after performing the tension introduction process. Therefore, in the tension introduction process, the slab bars do not get in the way, and it becomes possible to more efficiently introduce the tension using a tension jack or the like from the beam side surface of the main girder portion where the slab bars do not protrude.

[0014] The fifth characteristic configuration of the present invention is a method for constructing a structure according to claim 1 or 2, wherein in the member manufacturing process, the width of the precast beam member is set to be the same for the main girder portion and the secondary beam.

[0015] According to this configuration, in the member manufacturing process, it is possible to suppress the occurrence of steps on both outer side surfaces in the width direction of the precast beam member. Therefore, it is possible to suppress the complication of the formwork for manufacturing the precast beam member and improve the manufacturability of the precast beam member.

Brief Description of the Drawings

[0016]

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Embodiments for Carrying Out the Invention

[0017] Embodiments of the building construction method of the present invention will be described with reference to the drawings. FIG. 1 shows a plan view of the main part of the building structure constructed by the building construction method of the present invention. In this structure, a plurality of large RC beams 1 installed between a pair of columns (not shown) and a plurality of small RC beams 2 installed between a pair of adjacent large beams 1 are provided. The small RC beam 2 is prestressed to cope with the wide installation interval between the pair of large beams 1.

[0018] And, as shown in the process diagram of FIG. 7, this building construction method sequentially performs a member manufacturing step S1 of manufacturing a precast beam member 3 made of precast concrete having a small beam 2 as a main component, a tension force introduction step S2 of introducing a tension force into the precast beam member 3 to apply prestress to the small beam 2, and a building body construction step S3 of installing the precast beam member 3 at the building construction location A to construct the large beam 1 and the small beam 2. Hereinafter, each step S1 to S3 will be described in detail.

[0019] 〔Member Manufacturing Step〕 First, the configuration of the precast beam member 3 will be described with reference to FIGS. 2 to 6, and then the member manufacturing step S1 will be described.

[0020] As shown in Fig. 2, the precast beam member 3 is an integrated structure of a part of the main beam portion 1A in the longitudinal direction Y of the main beam 1 (which may be referred to as the width direction Y of the precast beam member 3) where the secondary beam 2 is connected to the main beam 1 and the secondary beam 2. In this embodiment, the precast beam member 3 is integrated with the above-described main beam portions 1A at both ends of the secondary beam 2 in the material axis direction X thereof.

[0021] As shown in Fig. 6, a sheath pipe 3B is built in the precast beam member 3 over the entire length in the material axis direction X. A PC steel material 4 into which a tension force is introduced in a tension force introduction step S2 described later is inserted into the sheath pipe 3B. Although not shown, the tip side of the PC steel material 4 is fixed to the beam side surface 1f of one of the main beam portions 1A in the precast beam member 3 with a fixing tool or the like, and in the tension force introduction step S2, a tension force is introduced into the PC steel material 4 from the beam side surface 1f of the other main beam portion 1A in the precast beam member 3.

[0022] As shown in Fig. 2, the width W3 of the precast beam member 3 is set to be the same for the main beam portion 1A and the secondary beam 2. In other words, the area of the main beam portion 1A is set to have the same width as the secondary beam 2. Incidentally, in this embodiment, as shown in Figs. 3 and 5, the upper surface 1k of the main beam portion 1A is set to a height flush with the upper surface of the slab (not shown), while the upper surface 2k of the secondary beam 2 is set to a height located at the upper and lower middle portion of the slab, and the upper surface 2k of the secondary beam 2 is positioned lower than the upper surface 1k of the main beam portion 1A.

[0023] As shown in Fig. 6, main bars 2a for the secondary beam and stirrup bars 2b for the secondary beam are arranged in the secondary beam 2 of the precast beam member 3, and the ends of the arranged main bars 2a for the secondary beam are embedded and fixed in the main beam portion 1A. Further, as shown in Fig. 5, stepped portions 2d having mounting surfaces for mounting and supporting the outer edge portions of the slab formwork 9 are formed at both end edges in the width direction Y at the upper part of the secondary beam 2 of the precast beam member 3 in a building structure construction step S3 described later.

[0024] As shown in Fig. 6, main reinforcement bars 1a for the main beam and stirrup bars 1b for the main beam are arranged in the main beam portion 1A of the precast beam member 3. As shown in Fig. 5, the ends of the arranged main reinforcement bars 1a for the main beam project as connection joints from the upper and lower parts of the surface (both outer side surfaces in the width direction Y of the precast beam member 3) 1d facing the main beam length direction Y in the main beam portion 1A. Also, in the upper and lower intermediate portions of the surface 1d facing the main beam length direction Y in the main beam portion 1A, a shallow recess 1e for forming a cotter for transmitting shear force between the main beam connection portion 1B constructed with in-situ concrete in the building construction process S3 described later is formed. The recess 1e is configured as a groove extending along the material axis direction X.

[0025] As shown in Fig. 5, a connected member 1g into which the slab reinforcement 12 can be inserted and connected is embedded in the beam side surface 1f (the beam side surface opposite to the secondary beam 2 in the main beam portion 1A) of the main beam portion 1A which is the end face in the material axis direction X of the precast beam member 3. This connected member 1g is composed of a cylindrical member having connection ports at both ends, such as a Tough Lock Joint (trade name) manufactured by Koyo Seiko Co., Ltd., and is embedded in the beam side surface 1f of the main beam portion 1A with one connection port exposed on the beam side surface 1f of the main beam portion 1A. Note that a fixing bar 11 for fixing the slab reinforcement 12 to the main beam portion 1A is connected to the other connection port of the connected member 1g. Also, as shown in Figs. 5 and 6, on the beam side surface 1f of the main beam portion 1A of this precast beam member 3, a fixture installation portion 1h for installing a fixture 6 for fixing the end of the PC steel material 4 in a state where a tension force is introduced by a tension jack 5 in the tension force introduction process S2 described later is formed.

[0026] In the member manufacturing process S1, a precast concrete bed (a formwork for precast concrete) in the shape of a box or the like with an upper part open and having an inner surface shape corresponding to the front, rear, left, and right peripheral side surfaces and the bottom surface of the precast beam member 3 described above is installed at the manufacturing site such as the manufacturing site within the site. Then, at a predetermined location inside the bed for precast concrete, main reinforcement bars 1a for the main beam, stirrup bars 1b for the main beam, main reinforcement bars 2a for the secondary beam, stirrup bars 2b for the secondary beam, sheath pipes 3B, connected members 1g, and fixing bars 11 are arranged, and profiles and the like for forming the concave portion 1e of the main beam portion 1A, the stepped portion 2d of the secondary beam 2, and the upper surface 2k of the secondary beam 2 are arranged. After that, concrete is placed inside the bed for precast concrete, and after waiting for the concrete to harden, the precast beam member 3 is extracted from the bed for precast concrete, and the production of the precast beam member 3 is completed. The produced precast beam member 3 is stored at a storage site for precast beam members within the site.

[0027] 〔Tension introduction process〕 As shown in FIG. 6, this tension introduction process S2 is a process of introducing tension to the PC steel material 4 from the beam side surface 1f of the main beam portion 1A of the precast beam member 3 to apply prestress to the secondary beam 2, and is performed, for example, at a storage site for precast beam members within the site.

[0028] In this embodiment, in the member production process S1 as the previous process, the base end side of the PC steel material 4 whose tip end side is fixed to the beam side surface 1f of one main beam portion 1A in the precast beam member 3 is drawn out to the outside from the fixture installation portion 1h on the beam side surface 1f of the other main beam portion 1A in the precast beam member 3. Therefore, in this tension introduction process S2, the tension is introduced to the PC steel material 4 by pulling the drawn-out portion of the PC steel material 4 with a tension jack 5 on the beam side surface 1f of the other main beam portion 1A in the precast beam member 3. Since no protrusions that would interfere with the tensioning operation of the main reinforcement bars 2a for the secondary beam, slab bars, etc. are present on the beam side surface 1f of the main beam portion 1A of the precast beam member 3, the tension can be introduced with good workability using the tension jack 5. Then, while maintaining the tension introduction state, the base end side of the PC steel material 4 is fixed with a fixture 6, and the inside of the fixture installation portion 1h and the sheath pipe 3B is filled with grout, and after waiting for the grout to harden, the application of prestress to the secondary beam 2 is completed.

[0029] 〔Building structure construction process〕 As shown in FIGS. 8 and 9, this body construction process S3 is a process of constructing the main beam 1 and the secondary beam 2 by installing the precast beam member 3 at the construction site A. In this embodiment, since the tension introduction process S2 is performed at a manufacturing site different from the construction site A, the precast beam member 3 after tension introduction is lifted and moved from the manufacturing site by a crane or the like and installed at the construction site A.

[0030] First, as shown in FIGS. 8(A) and (B), at the construction site A, the bottom formwork 7A for the main beam for forming the bottom surfaces of a pair of adjacent main beams 1 is pre-installed in a state of being supported by the lower shoring 8. Then, the main beam portions 1A at both ends of the precast beam member 3 are placed on the pair of pre-installed bottom formworks 7A for the main beam, and a plurality of precast beam members 3 are installed at predetermined intervals corresponding to the arrangement intervals of the secondary beams 2 in the main beam length direction Y in a state of bridging the precast beam member 3 between the pair of bottom formworks 7A for the main beam. By bridging the precast beam member 3 between the pair of bottom formworks 7A for the main beam in this way, the shoring directly below the secondary beam 2 can be omitted or reduced, labor can be saved in the work, and a wide space can be secured directly below the secondary beam 2 and effectively utilized as a rest area or a material storage area.

[0031] Next, as shown in FIGS. 9(A) and (B), the side formwork 7B for the main beam for forming the beam side surface 1f of the main beam 1 is installed, and main beam main reinforcement 1a and main beam stirrup bars (not shown) are arranged in the space between the main beam portions 1A of adjacent precast beam members 3 on the bottom formwork 7A for the main beam. Furthermore, a slab formwork 9 is installed between adjacent secondary beams 2 of the precast beam members 3, and slab reinforcement 10 is arranged above the slab formwork 9 and the secondary beam 2 as shown in FIG. 9(B). In FIG. 9(A), the slab reinforcement 10 is omitted. As described above, since step portions 2d having mounting surfaces for mounting and supporting the outer edge portions of the slab formwork 9 are formed at both end edges in the width direction Y of the upper part of the secondary beam 2 of the precast beam member 3, the slab formwork 9 can be easily installed at a predetermined height position.

[0032] Then, on the bottom formwork 7A for the main beam, concrete is placed in the space between the main beam portions 1A of adjacent precast beam members 3, and concrete is also placed above the formwork 9 for the slab and the secondary beam 2. Then, after waiting for the concrete to harden, the bottom formwork 7A and the side formwork 7B for the main beam are removed, and the main beam 1 and the secondary beam 2 and the slab can be constructed in a form where the main beam portions 1A of adjacent precast beam members 3 are connected at the main beam connection portion 1B (see FIG. 1).

[0033] In addition, in this embodiment, the case where the structure having the main beam 1 and the secondary beam 2 and the slab on the side of the secondary beam 2 as viewed from the main beam 1 are constructed simultaneously has been shown as an example. However, the slab on the side opposite to the secondary beam 2 as viewed from the main beam 1 may be constructed simultaneously. When constructing the slab on the side opposite to the secondary beam 2 as viewed from the main beam 1, the slab reinforcement can be inserted and connected to the connected member 1g (see FIG. 5) embedded in the beam side surface of the main beam portion 1A of the precast beam member 3.

[0034] 〔Alternative Embodiment〕 Another embodiment of the present invention will be described. Note that the configurations of each of the embodiments described below are not limited to being applied alone, and can also be applied in combination with the configurations of other embodiments.

[0035] (1) In the above-described embodiment, as shown in FIGS. 3 and 5, the upper surface 1k of the main beam portion 1A is set to a height flush with the upper surface of the slab (not shown), while the upper surface 2k of the secondary beam 2 is set to a height located at the upper and lower middle portion of the slab, and the case where the upper surface 2k of the secondary beam 2 is lower than the upper surface 1k of the main beam portion 1A has been shown as an example. Instead of this, as shown in FIGS. 10(A) and (B), the upper surface 1k of the main beam portion 1A is set to a height flush with the upper surface of the slab (not shown), and the upper surface 2k of the secondary beam 2 may also be set to a height flush with the upper surface of the slab (not shown), and the upper surface 2k of the secondary beam 2 and the upper surface 1k of the main beam portion 1A may be set to the same height. In this case, the slab reinforcement 10 can be arranged in the upper portion of the secondary beam 2 in the precast beam member 3, and the end portion of the arranged slab reinforcement 10 can project from the beam side surface 2f of the secondary beam 2.

[0036] (2) In the foregoing embodiment, as an example of the precast beam member 3 manufactured in the member manufacturing step S1, the one in which the large beam portions 1A of the pair of large beams 1 are integrated with both end portions of the small beam 2 (see FIG. 2) was described. However, the large beam portion 1A of one of the pair of large beams 1 may be integrated with the end portion of the small beam 2.

[0037] (3) In the foregoing embodiment, as shown in FIG. 5, the case where the connected member 1g into which the slab bars can be inserted and connected is embedded in the beam side surface 1f of the large beam portion 1A of the precast beam member 3 manufactured in the member manufacturing step S1 was shown as an example. However, when the connection of the slab bars is unnecessary or the like, the connected member 1g can be omitted.

[0038] (4) In the foregoing embodiment, as shown in FIG. 2, the case where the width W3 of the precast beam member 3 is set to be the same for the large beam portion 1A and the small beam 2 was shown as an example. However, depending on the case, the width of the large beam portion 1A may be made larger or smaller than the width of the small beam 2.

Explanation of Reference Numerals

[0039] 1 Large beam 1A Large beam portion 1f Beam side surface of the large beam portion 1g Connected member 2 Small beam 3 Precast beam member 4 PC steel material 7A Bottom formwork for large beam A Structure construction location S1 Member manufacturing step S2 Tension introduction step S3 Frame construction step X Material axis direction Y Large beam length direction (width direction of the precast member) W3 Width of the precast member

Claims

1. A method for constructing a structure in which prestressed RC small beams are installed between a pair of large RC beams, comprising: a member manufacturing step of manufacturing a part of the large beam in the longitudinal direction of the large beam to which the small beam is connected in the large beam and the small beam as an integral precast beam member made of precast concrete; a tension introduction step of introducing a tension force into PC steel bars from the beam side surface of the large beam portion which is the end surface in the material axis direction of the precast beam member to apply prestress to the small beam; a structure construction method including a body construction step of installing the precast beam member at a structure construction location to construct the large beam and the small beam.

2. In the body construction step, a plurality of the large beam portions of the precast beam members are placed at intervals on a previously installed bottom formwork for the large beam, The construction method of the structure according to claim 1, wherein concrete is placed in a space between the large beam portions of the adjacent precast beam members on the bottom formwork for the large beam.

3. In the member manufacturing step, the large beam portions of the pair of large beams and the small beam are manufactured as the integral precast beam member, In the body construction step, the precast beam member is spanned between a pair of bottom formworks for the large beam in a state where the large beam portions at both ends of the precast beam member are placed on the previously installed pair of bottom formworks for the large beam. The construction method of the structure according to claim 1 or 2.

4. The construction method of the structure according to claim 1 or 2, wherein in the member manufacturing step, a connecting member into which slab bars can be inserted and connected is embedded in the beam side surface of the large beam portion of the precast beam member.

5. The construction method of the structure according to claim 1 or 2, wherein in the member manufacturing step, the width of the precast beam member is set to be the same for the large beam portion and the small beam.

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