JP5548637B2 - Construction method of underground beam - Google Patents

Description

  The present invention relates to a construction method of an underground beam in which concrete of an underground beam is cast to the lower end of a floor slab, and then the concrete is horizontally transferred to the upper end of the underground beam simultaneously with the floor slab.

  For the construction of underground beams by on-site casting of concrete, first of all, the concrete of the underground beam is cast to the lower end of the floor slab, and then the concrete to the upper end of the underground beam at the same time as the floor slab. It is often done by a method such as transferring the image horizontally.

  Since the structural performance required for the joint surface of concrete is “shear transmission”, it is necessary to thoroughly clean the joint surface prior to the joint and clean it. However, even if such considerations are made, it is not a problem as to whether or not the concrete placed in advance and the concrete overlaid on it at a time are completely integrated structurally. There is.

  Therefore, for example, when the concrete of the floor slab is handed over to the precast concrete beam on the general floor, as described in Patent Document 1, as a means for ensuring the integrity with the concrete handed over at the site, At the time of production of precast concrete beams, a fine concavo-convex horizontal splicing cotter is formed on the upper end surface of the precast concrete beams, or a steel dowel is protruded. As described in No. 2, a technique for projecting a shear connector made of a spiral reinforcing bar on the upper surface of the central portion of a precast concrete beam has been proposed and partially put into practical use.

  However, any of these known techniques is a technique adopted at the time of manufacturing a precast concrete beam, and is difficult to apply to construction of an underground beam by on-site casting of concrete. For example, even if you attempt to project a shear connector made of steel “dowel” or spiral rebar on the upper surface of the underground beam, there are a number of main bars and them in the side formwork of the underground beam. Numerous barbs that are surrounded at small intervals are arranged, and these rebars become obstacles when setting steel “dowels” and spiral rebars, and efficient construction on site cannot be expected.

JP-A-6-10404 Japanese Patent No. 2791239

  The present invention has been made in view of the above-described problems, and the purpose thereof is a shear force at a horizontal joint surface even though it is an underground beam constructed by in-situ concrete casting. The construction method of the underground beam with good workability by improving the integrity of the underground beam concrete that has been placed in advance and the concrete to be transferred and reducing the reinforcement for the connection Is to provide.

In order to achieve the above object, the technical means taken by the present invention are as follows. That is, in the construction method of the underground beam according to the first aspect of the invention, the concrete of the underground beam is cast to the lower end of the floor slab, and then the concrete is horizontally transferred to the upper end of the underground beam simultaneously with the floor slab. A method for constructing underground beams, in which a pair of vertical partition plates is set at an upper part between the side molds of the underground beam and at a position where the span length in the beam is divided into approximately three equal parts. The underground beam concrete is driven to a predetermined level in the space between the molds to form a horizontal jointing cotter that is located over the entire length in the beam width direction at the center of the beam. It is characterized by that.

  The invention according to claim 2 is the construction method of the underground beam according to claim 1, wherein the concrete for the underground beam in the space between the side molds, up to the upper end level of the partition plate between the partition plates, It is characterized in that it is driven from the partition plate to both ends of the beam up to the lower end level of the partition plate, and a convex horizontal splicing cotter is formed at the center of the beam.

  The invention according to claim 3 is the construction method of the underground beam according to claim 1, the concrete for the underground beam in the space between the side molds, to the lower end level of the partition plate between the partition plates, It is characterized in that it is driven from the partition plate to both ends of the beam up to the upper end level of the partition plate, and a concave horizontal splicing cotter is formed at the center of the beam.

  According to said structure, there exists an effect which can construct the underground beam which can ensure the integrity of the underground beam concrete and the concrete to be handed over easily.

  That is, when placing underground beam concrete to the lower end of the floor slab, before placing the upper main bar of the underground beam, insert a partition plate perpendicular to the gap between the reinforcing bars and set it in the side formwork. Therefore, a horizontal jointing cotter located over the entire length in the beam width direction can be easily formed by in-situ casting the concrete into a predetermined level in the side mold using the partition plate as a dam plate.

  In particular, the pair of vertical partition plates is set at a position that divides the in-beam normal span length into approximately three equal parts. A horizontal jointing cotter will be formed, the transmission of the shear force at the jointing surface of the concrete will be reliable, and the integrity of the underground beam concrete previously placed and the concrete to be handed over will be ensured it can.

  According to the second aspect of the present invention, the convex horizontal jointing cotter positioned over the entire length in the beam width direction can be easily molded. According to the third aspect of the present invention, the cotter for the horizontal width is positioned over the entire length in the beam width direction. A concave horizontal splicing cotter can be easily molded.

It is a perspective view which illustrates the construction method of the underground beam which concerns on this invention. It is a side view of the underground beam which cast concrete to the lower end of a floor slab. It is a schematic perspective view of the principal part explaining the cotter for horizontal joining. It is a schematic perspective view of the principal part explaining the cotter for horizontal joining which shows other embodiment of this invention. It is a side view of an underground beam which has the cotter for horizontal joining shown in FIG.

1 to 3 show a construction method of an underground beam according to the present invention. In the figure, 1 is a footing of a pile head, 2 is an underground beam in which concrete has been cast in advance to the lower end of the floor slab, 2a is a through hole, 3 is a reinforcing bar protruding above the underground beam 2, 4 Indicates the main column. 5a is a convex horizontal splicing cotter formed over the entire length in the beam width direction and formed at the upper part of the center of the underground beam 2. In addition, the underground beam main bar is not shown in order to simplify the drawing. Horizontal cotter 5
a is formed at a position that divides the span length L in the beam into approximately three equal parts, and the length of the horizontal splicing cotter 5a is 1 / 3L that divides the span length L in the beam into approximately three equal parts. The height of the horizontal joining cotter 5a is set to about several hundred mm (specifically, about 200 to 300 mm).

  The horizontal splicing cotter 5a has a pair of vertical portions having a height of about 200 to 300 mm at the upper part between the side molds 6 of the underground beam and at a position that divides the in-beam span length L into approximately three equal parts. The partition plate 7 is set, and in this state, the underground beam concrete 8 is divided into the space between the side molds 6 up to the upper end level of the partition plate 7 between the partition plates 7 and from the partition plate 7 to both ends of the beam. It is formed by driving to the lower end level of the plate 7. As shown in FIG. 3, the partition plate 7 is inserted between the side molds 6 through the gap of the barb 3, and an appropriate fixing means such as an angled fastener (not shown), a nail, a screw, an adhesive tape, etc. Can be fixed to the side mold 6.

  Thereafter, by performing the horizontal jointing of the concrete, it is possible to reliably transmit the shearing force at the horizontal jointing surface, and to ensure the integrity of the underground beam concrete 8 previously placed and the concrete to be handed over. Underground beams will be built.

4 and 5 show another embodiment of the present invention. In this embodiment, the underground beam concrete 8 is placed in the space between the side molds 6 up to the lower end level of the partition plate 7 between the partition plates 7, and the upper end level of the partition plate 7 from the partition plate 7 to both ends of the beam. And a concave horizontal splicing cotter 5b is formed at the center of the beam. Since the configuration and action of the length, depth, position, etc. of the horizontal splicing cotter 5b are the same as those in the embodiment of FIGS.

  According to said structure, the underground beam which can ensure the integrity of the underground beam concrete 8 and the concrete to be handed over can be constructed easily.

  That is, when placing the underground beam concrete to the lower end of the floor slab, the partition plate 7 perpendicular to the gap of the reinforcing bar 3 can be inserted and set in the side mold 6, so that the partition plate 7 can be By casting concrete into the side mold 6 as a plate to a predetermined level, the convex or concave horizontal jointing cotter 5a or 5b positioned over the entire length in the beam width direction can be easily formed.

In particular, since the pair of vertical partition plates 7 is set at a position that divides the in-beam normal span length L into approximately three equal parts, the in-beam normal span length L is approximately divided into three equal parts above the underground beam. The horizontal jointing cotter 5a or 5b having a length of 1 / 3L is formed, the transmission of the shearing force on the jointing surface of the concrete is reliable, and the underground beam concrete 8 placed in advance is Integrates with the concrete to be handed over. The upper surface of the underground beam is a water jet (water pressure of 50 MPa) when the concrete strength is confirmed to be 10 N / mm ² or more after placing the concrete.
Degree).

  The underground beam construction method of the present invention can also be used for construction of a general floor beam.

DESCRIPTION OF SYMBOLS 1 Footing L Beam internal span length 2 Underground beam 2a Passage hole 3 Reinforcing bar 4 Column main bar 5a, 5b Horizontal joint cotter 6 Side formwork 7 Partition plate 8 Underground beam concrete

Claims (3)

  An underground beam construction method in which concrete of the underground beam is cast to the lower end of the floor slab, and then the concrete is horizontally transferred to the upper end of the underground beam simultaneously with the floor slab. A pair of vertical partition plates is set at the upper part of the space and at a position that divides the span length in the beam into approximately three equal parts. In this state, concrete for underground beams is driven to a predetermined level in the space between the side molds. Then, a method for constructing an underground beam is characterized in that a horizontal jointing cotter located over the entire length in the beam width direction is formed at the center of the beam, and then the concrete is jointed horizontally.   The concrete for the underground beam is placed in the space between the side molds, up to the upper end level of the partition plate between the partition plates, and up to the lower end level of the partition plate from the partition plate to both ends of the beam. 2. The underground beam construction method according to claim 1, wherein a horizontal cotter for forming the mold is formed.   Concrete for underground beams is placed in the space between the side molds, up to the lower end level of the partition plate between the partition plates, and up to the upper end level of the partition plate from the partition plate to both ends of the beam. The method for constructing underground beams according to claim 1, wherein a horizontal splicing cotter is formed.

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