JP2013053413A - Construction method for slab, shear reinforcement, and concrete beam structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve non-shoring construction of an overhang part of a half-precast slab.SOLUTION: A half-precast slab 4 is used which includes a main-body part 41 and overhang parts 42, a truss reinforcement 44 buried in those main-body part and overhang parts to be exposed on their top surfaces, and slab lower end reinforcements 43 exposed between the main-body part and overhang parts. Both side parts of the main-body part 41 and base-end parts of the overhang parts 42 are placed on beams 3 which are installed in parallel and each has lower shearing reinforcements 31 exposed on its upper surface. After a slab upper end reinforcement 46 and main reinforcements 32 of the beams 3 are arranged at upper part of the lower shearing reinforcements 31 and a part of the truss reinforcement 44 from above between the main-body part and the overhang parts, and an upper shearing reinforcement 6 in a shape over the upper parts of the lower shearing reinforcements 31 and the part of the slab lower end reinforcement 43 is arranged, concrete is cast such that the lower shearing reinforcements 31, the truss reinforcement 44, the slab lower end reinforcements 43, the slab upper end reinforcement 46, the main reinforcements 32 of the beams 3, and the upper shearing reinforcement 6 are buried.

Description

  The present invention relates to a slab construction method using a half precast slab, a shear reinforcing bar used therefor, and a concrete beam structure using the shear reinforcing bar.

In Patent Document 1, when a concrete structure having a ramen structure is constructed, a half precast slab installed in a state in which a pair of side edges facing each other with respect to the beam under construction is placed, and the half precast slab A method for constructing slabs is proposed.
In the half precast slab of Patent Document 1, the truss bars are embedded in a state protruding in the upper part, the lower end bars are embedded in advance, and prestress is introduced substantially along the direction connecting the pair of side edges, The slab body is arranged to extend over a predetermined length between the slab body having no haunch on the pair of side edges and the side edge of the slab body placed on the beam and the inside of the beam. And a lap joint bar embedded in the concrete to be placed on the upper part.
Then, the slab body is installed in a state where a pair of side edge portions facing each other are placed on the beam under construction, and the side edge portion of the slab body in a state placed on the beam, The lap joint bars are laid out in a state of straddling a predetermined length inside the beam, the upper end bars are laid out, and then the concrete is placed in a state where the lap joint bars are buried in the upper part of the slab body.

Patent Document 2 proposes a method for constructing a composite girder formed by a steel girder part having a stopper on the upper surface and a concrete floor slab.
The half precast of Patent Document 2 is only an overhanging portion that is placed on the steel girder portion outside the displacement stopper and is projected from the both side edges at both side edges of the upper surface flange of the steel girder portion. .
And a half precast overhanging part, a member for connecting the half precast overhanging parts, the lower part of both ends embedded in the half precast overhanging part, and the upper part protruding upward, The floor slab is formed by the cast-in-place concrete part that is placed on the half precast overhanging part and embeds the truss reinforcement.

JP 2004-339867 A JP 2010-101072 A

  However, the technique of Patent Document 1 is constructed by placing both side edges of a half-precast slab body on a beam, and it has been impossible to perform unsupported construction of the overhanging slab.

The technique of Patent Document 2 is a composite girder composed of a steel girder part and a concrete floor slab, and only the overhanging part is made of half precast. In addition, a half precast slab having a projecting portion on the main body as in Patent Document 1 is not used.
Steel girders do not require the shear reinforcement necessary for reinforced concrete beams.

  The subject of this invention is enabling the non-support construction of the overhang | projection part of a half precast slab.

  In order to solve the above problems, the invention described in claim 1 is a precast concrete main body and overhang, and a truss embedded in the main body and overhang and exposed on the upper surface of the main body and overhang. Using a half precast slab comprising a streak and a slab bottom streak embedded in the main body part and the overhanging part and exposed between the main body part and the overhanging part, the lower shear reinforcement bar is installed in parallel and has a lower shear reinforcement bar on the upper surface. Place both side parts of the main body part and the base end part of the overhanging part on the exposed beam, and between the main body part and the overhanging part, on the upper part of the lower shear reinforcement bar and the truss bar part. The upper part of the slab and the main bar of the beam are arranged from above, and the main bar of the beam is arranged, and then the upper part of the lower shear reinforcement and the lower part of the slab are formed. A method for constructing a slab, in which concrete is placed in a state in which the lower shear reinforcing bar, the truss bar, the lower slab bar, the upper slab upper bar, and the upper shear bar are embedded after arranging the shear reinforcing bars of It is characterized by.

  Invention of Claim 2 is the construction method of the slab of Claim 1, Comprising: The said upper shear reinforcement is diagonally downward from the both sides of the linear part along the upper part of the said lower shear reinforcement. A curved portion that extends and curves is overlapped on the upper surface of the beam.

  Invention of Claim 3 is a shear reinforcement used for the construction method of the slab of Claim 1, Comprising: The part corresponding to the upper part of the lower shear reinforcement, and the lower end reinforcement of the slab And a portion.

  Invention of Claim 4 is a shear reinforcement used for the construction method of the slab of Claim 2, Comprising: The said linear part made to fit along the upper part of the said lower shear reinforcement, Both sides of the said linear part And a curved portion that extends obliquely downward from the curved portion and is curved.

  The invention according to claim 5 is a concrete beam structure using the shear reinforcement according to claim 3 or 4, wherein the lower surface of the concrete is exposed on the upper surface of the concrete, and the beam is placed on the upper surface of the beam. Precast concrete slab body and slab overhang, trusses and slab bottom bars exposed between the slab body and slab overhang, upper part of the lower shear reinforcement and parts of the truss bars Slab upper bar and the main bar of the beam, the upper shear reinforcement bar arranged over the lower shear reinforcement bar and the lower slab lower bar part, and the lower shear reinforcement bar , Slab bottom bar, slab top bar, beam main bar, and concrete placed in a state where the upper shear reinforcement bar is embedded.

  According to the present invention, the projecting portion of the half precast slab can be constructed without any support.

It is the front view which showed the structure of one Embodiment of the construction method of the slab to which this invention was applied, and showed the method of erection of the half precast slab to a viaduct. It is the figure which showed the reinforcement assembly following FIG. It is an enlarged view of the arrow A part of FIG. It is an enlarged view similar to FIG. 3, and is a view of a bar arrangement portion of the slab upper end muscle. It is a perspective view of an upper shear reinforcement. Side view (a) showing the arrangement of the lower shear reinforcement, truss and bottom slab bars on the beam with the half precast slab on the beam, (b) showing the arrangement of the main bars of the beam, It is the figure (c) which showed arrangement | positioning of the upper shear reinforcement. It is the figure which showed the cast-in-place concrete placement following FIG. It is the front view which showed the example of general reinforcement arrangement | positioning of a beam.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
(Embodiment)
FIG. 1 shows a construction method of a half precast slab on a viaduct as a configuration of an embodiment of a slab construction method to which the present invention is applied. 1 is a column, 2 is a transverse beam, 3 is a longitudinal beam, Half precast slabs and 5 are suspension jigs.

  As shown in the figure, a concrete horizontal beam 2 is installed between the left and right concrete columns 1, and a concrete vertical beam 3 is installed between the left and right columns 1. In the vertical beam 3, lower shear reinforcement bars 31 are exposed on both the left and right sides of the upper surface. The half precast slab 4 is lifted by a crane (not shown) via a lifting jig 5 and placed on the left and right vertical beams 3 in parallel.

  The half precast slab 4 includes a main body portion 41 placed on both sides of the parallel left and right vertical beams 3 and installed between them, and an overhanging portion 42 which is spaced apart on the left and right and placed on the vertical beam 3 with the base end portion installed. The slab lower end bar 43 is embedded in the precast concrete of the main body part 41 and the overhanging part 42, and the lower part of the truss bar 44 is embedded, and the slab upper end bar 45 is exposed at both end parts of the left and right overhanging parts 42. doing. The slab lower end stripe 43 is exposed between the main body portion 41 and the overhang portion 42.

  Next, FIG. 2 shows the rebar assembly. As shown in the drawing, between the main body portion 41 and the overhanging portion 42 of the half precast slab 4, between the upper portions of the lower side shear reinforcement bars 31. After the main bar 32 of the longitudinal beam 3 is laid from the upper side in the upper part of the truss bar 44, the slab upper bar 46 is laid between the slab upper bar 45 on both side ends on the left and right projecting portions 42.

  FIG. 3 is an enlarged view of an arrow A portion in FIG. 2, and FIG. 4 similarly shows a bar arrangement portion of the slab upper end reinforcement 46.

  Then, as shown in the figure, the upper shear reinforcement bars 6 are arranged so as to straddle the upper part of the lower shear reinforcement bars 31 on the left and right sides and the slab lower end bars 43.

  That is, as shown in FIG. 5, the upper shear reinforcement bar 6 is formed with a curved portion 62 that is curved obliquely extending from both sides of the linear portion 61 that extends in the left-right direction.

  As shown in FIGS. 3, 4, and 6, the upper shear reinforcing bar 6 is placed along the straight part 61 on the upper part of the lower left and right side shear reinforcing bars 31, and both sides of the straight part 61. The curved portion 62 extending obliquely downward from the slab is placed below the slab lower bar 43 so as to overlap the upper surface of the vertical beam 3.

  Here, FIG. 6 shows a state in which the half precast slab 4 is placed on the longitudinal beam 3, and FIG. 6A shows a lower shear reinforcement bar 31, a truss bar 44 and a slab lower end bar 43 on the longitudinal beam 3. FIG. 6B shows the arrangement of the main bars 32 of the longitudinal beam 3, and FIG. 6C shows the arrangement of the upper shear reinforcement bars 6.

  In the longitudinal direction of the longitudinal beam 3, as shown in FIG. 6A, a slab lower bar 43 and a truss bar 44 are arranged between the lower shear reinforcement bars 31, as shown in FIG. 6B. In addition, the main bar 32 of the longitudinal beam 3 is arranged in the upper part of the truss bar 44 between the upper parts of the lower shear reinforcement bars 31.

  Then, as shown in FIG. 6 (c), the upper shear reinforcement 6 has a curved portion 62 extending obliquely downward from both sides of the straight portion 61 along the upper part of the lower shear reinforcement 31, and the lower end of the slab. The fixed length of cast-in-place concrete performed in the next process is secured by overlapping the upper surface of the vertical beam 3 along the lower side of 43.

  Next, FIG. 7 shows cast-in-place concrete placement. As shown by the hatched area on the vertical beam 3 and the half precast slab 4, the shear reinforcement bar 31 and the main bar 32 below the vertical beam 3, Concrete is placed in a state where the slab lower bar 43, the truss bar 44, the slab upper bars 45 and 46, and the upper shear reinforcement bar 6 are embedded.

  After the concrete is placed, the viaduct slab is constructed through a predetermined drying and solidification and curing period.

As mentioned above, the construction method of the slab using the half precast slab 4 of the embodiment is as follows.
1) A step of placing both side portions of the main body portion 41 and the base end portion of the overhanging portion 42 on the vertical beam 3 which is installed in parallel and the lower shear reinforcing bar 31 is exposed on the upper surface;
2) A step of arranging the slab upper end muscle 46 and the main bar 32 of the longitudinal beam 3 from above the upper part of the lower shear reinforcement bar 31 and the portion of the truss bar 44 between the main body part 41 and the overhanging part 42;
3) A step of arranging the upper shear reinforcement 6 having a shape straddling the upper part of the lower shear reinforcement 31 and the slab lower end reinforcement 43,
4) A step of placing concrete in a state where the lower shear reinforcing bar 31, truss bar 44, slab lower bar 43, slab upper bar 46, main bar 32 of the longitudinal beam 3 and upper shear reinforcing bar 6 are embedded.
Consists of.

FIG. 8 shows an example of a general reinforcing bar arrangement of a beam. As shown in the figure, a lower shear reinforcing bar 81 and an upper shear reinforcing bar 82 are generally arranged on the beam 8. .
If the beam 8 having such a bar arrangement structure is made to correspond to the installation of the half precast slab, the concrete stop position at the time of laying the half precast slab becomes a position crossing the covering reinforcement 82 as shown by the dotted line. After the main bar 83 is arranged, the upper shear reinforcing bar 82 cannot be arranged.
In addition, after the upper shear reinforcement bar 82 is arranged, the main bar 83 must be inserted from the beam axis direction.

  On the other hand, in the vertical beam 3 according to the embodiment, the lower shear reinforcement bar 31 is exposed on the upper surface, and therefore, after the main bar 32 is arranged, the linear portion is formed above the lower side shear reinforcement bar 31 on both the left and right sides. 61, and the curved portion 62 extending obliquely downward from both sides of the straight portion 61 is superposed on the upper surface of the longitudinal beam 3 along the lower side of the slab lower bar 43, thereby arranging the upper shear reinforcement bar 6 And shear reinforcement.

  As mentioned above, according to the construction method of the slab of the embodiment, the projecting portion 42 of the half precast slab 4 can be constructed without being supported.

(Modification)
In the above embodiment, although it was set as high bridge, this invention is not limited to this, A common building may be sufficient.
Further, in the embodiment, the lower shear reinforcement bars on the two lower sides of the beam are covered with the upper shear reinforcement bars, but the two lower shear reinforcement bars are provided on the inner side, and the inner two reinforcement bars are provided. The lower shear reinforcement may be covered with the upper shear reinforcement.
Furthermore, after arranging the main bar of the beam, the upper end of the slab may be arranged, or after arranging the upper shear reinforcement, the upper end of the slab may be arranged.
Further, the number of shear reinforcement bars is arbitrary, and it is needless to say that other specific detailed structures can be appropriately changed.

DESCRIPTION OF SYMBOLS 1 Column 2 Horizontal beam 3 Vertical beam 31 Lower shear reinforcement 32 Main reinforcement 4 Half precast slab 41 Main body part 42 Overhanging part 43 Slab lower end reinforcement 44 Truss reinforcement 45 Slab upper reinforcement 46 Slab upper reinforcement 5 Lifting jig 6 Upper shear reinforcement Muscle 61 Straight line part 62 Curved part

Claims (5)

Precast concrete main body part and overhanging part, truss bars embedded in these main body part and overhanging part and exposed on the upper surface of the main body part and overhanging part, embedded in the main body part and overhanging part and the main body part and Using a half precast slab with a slab bottom streak exposed between overhangs,
On the beam that is installed in parallel and exposes the lower shear reinforcement on the upper surface, place both sides of the main body and the base end of the overhang,
Between the main body portion and the overhanging portion, an upper end of the slab and the main bar of the beam are arranged from above to the upper part of the lower shear reinforcement bar and the truss bar, and the main bar of the beam is arranged. Then, after arranging the upper shear reinforcement which forms the upper part of the lower shear reinforcement and the portion of the lower end of the slab,
A method for constructing a slab, comprising placing concrete in a state in which the lower shear reinforcement bar, truss bar, slab lower bar, slab upper bar, beam main bar and upper shear reinforcement bar are embedded.   2. The curved portion that is curved downwardly extending from both sides of the straight portion along the upper portion of the lower shear reinforcement is overlapped on the upper surface of the beam. The construction method of the slab as described in 2. It is a shear reinforcement used for the construction method of the slab of Claim 1,
A portion corresponding to the upper portion of the lower shear reinforcement;
And a portion corresponding to the lower end reinforcement of the slab. It is a shear reinforcement used for the construction method of the slab of Claim 2,
The straight portion along the top of the lower shear reinforcement;
A shear reinforcing bar comprising: the curved part that extends obliquely downward from both sides of the straight part and curves. A concrete beam structure using the shear reinforcement according to claim 3 or 4,
A beam where the lower shear reinforcement is exposed on the top surface of the concrete;
A precast concrete slab body and slab overhang on the top of the beam;
Truss and slab lower end bars exposed between the slab body and the slab overhang,
An upper slab of the slab arranged in the upper part of the lower shear reinforcement and the truss part and the main reinforcement of the beam;
An upper shear reinforcement bar arranged across the upper part of the lower shear reinforcement bar and the lower end of the slab; and
A concrete beam structure comprising: the lower shear reinforcement bar, the truss bar, the lower slab barb, the upper slab barb, the main bar of the beam, and the concrete embedded in the upper shear bar. .

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