JP6368562B2 - Pile foundation structure - Google Patents

Description

  The present invention relates to a pile foundation structure.

  Patent Document 1 discloses a pile foundation structure in which a composite pile foundation member is composed of one newly installed pile and one or more existing piles. Moreover, in patent document 1, the buffering device is arrange | positioned at the upper part of the existing pile, and the footing is driven in the upper part of this buffering device and a new pile. Furthermore, the joint part of an underground beam (foundation beam) and a column is provided in the upper part of the footing.

JP 2002-146808 A

  In the configuration of Patent Document 1, the axial force acting on the pillar can be dispersed in a plurality of piles. However, since the joint part of the underground beam and the column is provided in the upper part of the footing, the height of the building may be higher than the ground level.

  In view of the above facts, an object of the present invention is to obtain a pile foundation structure including a plurality of piles and capable of suppressing the height of a building.

Pile foundation structure according to claim 1, possess a footing concrete is Da設the pile head of the plurality of piles, and steel foundation beams Joint portions between the pillars embedded in the footing concrete, the said footing The concrete includes a plurality of first footing concretes that are placed on the pile heads of the plurality of piles, and a second footing concrete that is formed integrally with the first footing concrete and connects the plurality of first footing concretes. The cross rib which supports the said steel foundation beam is provided in the position which overlaps with the center axis | shaft of the said pile in an elevation view on the said 1st footing concrete with a clearance gap between the ground .

  According to the pile foundation structure according to claim 1, footing concrete is placed on the pile heads of the plurality of piles, and the joint portion between the column and the steel foundation beam is embedded in the footing concrete. Thereby, the axial force which acts on a pillar can be disperse | distributed to a some pile. Moreover, the height of a building can be restrained compared with the structure provided with the joint part of a column and a steel frame foundation beam in the upper part of footing concrete.

Further , by supporting the steel foundation beam with the cross ribs with a gap between the ground and the ground, it is possible to suppress the rust generation on the steel foundation beam, and to ensure long-term reliability. Further, the configuration can be simplified as compared with the case of supporting the steel foundation beam using a steel pipe or the like.

  As described above, according to the pile foundation structure according to the present invention, a plurality of piles can be provided and the height of the building can be suppressed.

It is an elevational view showing a pile foundation structure according to the first embodiment. It is a top view which shows the pile foundation structure which concerns on 1st Embodiment. (A) is sectional drawing cut | disconnected by the 3A-3A line | wire of FIG. 1, (B) is sectional drawing cut | disconnected by the 3B-3B line | wire of FIG. 3A. It is a top view which shows the pile foundation structure which concerns on 2nd Embodiment.

<First Embodiment>
Hereinafter, a pile foundation structure according to the first embodiment of the present invention will be described with reference to the drawings. In each figure, the vertical direction (up and down direction) is indicated by an arrow Z, and two orthogonal directions in the horizontal direction are indicated by an arrow X and an arrow Y.

(Overall configuration of pile foundation structure 10)
As shown in FIG. 1, the pile foundation structure 10 according to this embodiment includes a plurality of piles 12. The plurality of piles 12 are driven into the ground 20 at intervals, and in this embodiment, as an example, four piles 12 are driven into the ground 20 (see FIG. 2). Here, a steel pipe pile formed in a substantially cylindrical shape is used as the pile 12, and a footing concrete 22 is placed on the pile head 12 </ b> A of each pile 12. A two-dot chain line L in the figure indicates the excavation range of the ground 20.

  In this embodiment, a steel pipe pile is used as the pile 12. However, the pile is not limited to this, and may be formed of other materials and structures. For example, a reinforced concrete pile, a prestressed concrete pile, a prestressed high strength concrete pile. Pile such as may be used. When existing piles are provided, the existing piles may be used for at least some of the piles 12. Conversely, all the piles 12 may be new piles.

  The footing concrete 22 placed on the pile head 12 </ b> A is formed in a substantially rectangular parallelepiped shape, and the upper end portion of the footing concrete 22 protrudes slightly upward from the ground 20. A plurality of main bars 24 are embedded in the upper and lower portions of each footing concrete 22, and shear reinforcement bars 26 are embedded so as to surround the main bars 24.

  Above the footing concrete 22, a steel-made column 16 and a plurality of steel foundation beams 14 are provided, and the joint portion 30 is constituted by the columns 16 and the steel foundation beams 14. As shown in FIG. 2, the column 16 is provided in a central portion of a region where the four piles 12 are driven in a plan view. In the present embodiment, as an example, the column 16 is formed of a square steel pipe. Yes.

  However, the present invention is not limited to this, and the column 16 may be formed of other materials and structures. For example, the column 16 may be formed of reinforced concrete, steel-framed reinforced concrete, CFT (Concrete-Filled Steel Tube), or the like. May be. In the present embodiment, the column 16 is provided in the central portion of the area where the four piles 12 are driven in a plan view. However, the present invention is not limited to this, and the column 16 is shifted from the central portion in the XY direction. It may be provided.

  Here, as shown in FIG. 1, a pair of upper and lower diaphragms 16 </ b> A is provided in the joint portion 30 in the column 16. Each of the diaphragms 16A is a through diaphragm, an outer diaphragm, or the like, and protrudes from the column 16 toward the outer peripheral side. One end of the steel foundation beam 14 is joined to the pair of diaphragms 16A by welding or the like.

  The steel foundation beam 14 is a steel structure foundation beam extending in the X direction and the Y direction. In the present embodiment, as an example, four steel foundation beams 14 are connected to four sides of the column 16. Each of the steel foundation beams 14 includes a pair of upper and lower flange portions 14A and 14C opposed to each other in the vertical direction, and a web portion 14B that vertically connects the pair of upper flange portions 14A and the lower flange portion 14C. It is formed of an H-shaped steel having a substantially H-shaped cross section.

  In addition, as shown in FIG. 2, the steel foundation beam 14 has both sides in the X direction and Y direction with respect to the steel column 16 provided in the central portion of the area where the four piles 12 are driven. Are extended to both sides of the pile 12 and are arranged in the central portion of the piles 12 adjacent in plan view. One end portion of the upper flange portion 14A of the four steel foundation beams 14 is connected to the upper diaphragm 16A, and as shown in FIG. 1, one end portion of the lower flange portion 14C is connected to the lower diaphragm 16A. It is connected. Further, one end portion of the web portion 14 </ b> B is connected to the outer peripheral portion of the column 16.

  The web portion 14B and the pillar 16 may be connected via a gusset plate or the like. In the present embodiment, the H-shaped steel is used as the steel foundation beam 14. However, the present invention is not limited to this. For example, the steel foundation beam 14 is formed using I-shaped steel, C-shaped steel, T-shaped steel or the like. Also good.

  Here, the reinforcing rib 32 is provided from the web part 14B of the steel foundation beam 14 toward the direction orthogonal to the web part 14B. The reinforcing rib 32 is provided at a position overlapping the central axis C of the pile 12 in an elevational view, and extends vertically so as to connect the upper flange portion 14A and the lower flange portion 14C. In addition, not only this but the reinforcement rib 32 may be provided in the position shifted | deviated to the X direction with respect to the central axis C of the pile 12. FIG. Furthermore, a plurality of reinforcing ribs 32 may be provided at intervals in the X direction.

  As shown in FIG. 3A, the reinforcing ribs 32 are provided on both surfaces of the web portion 14B of the steel foundation beam 14, and are formed so as to gradually widen downward from the upper flange portion 14A. Has been. Further, the lower end portion of the reinforcing rib 32 is positioned outside the lower flange portion 14C, and is joined to a support plate 36 provided on the upper surface of the cross rib 28 described later by welding or the like.

  As shown in FIG. 1, the steel foundation beam 14 is supported by a cross rib 28 described later with a gap 34 between the ground 20. That is, the joint portion 30 between the steel frame foundation beam 14 and the column 16 is provided in a state of floating above the ground 20 above the ground 20.

  Here, the joint portion 30 between the column 16 and the steel foundation beam 14 is embedded in the footing concrete 18 formed integrally with the footing concrete 22 placed on the pile head 12A.

  The footing concrete 18 is formed in a substantially rectangular parallelepiped shape, and is integrally formed with four footing concretes 22 placed on the pile heads 12A of the four piles 12 (see FIG. 2). In addition, a plurality of main bars 24 are embedded in the upper end portion of the footing concrete 18 at substantially equal intervals, and a plurality of main bars 24 are also embedded in both ends of the footing concrete 18 in the X direction. A shear reinforcing bar 26 is embedded so as to surround these main bars 24. Furthermore, a plurality of main bars 24 and shear reinforcement bars 26 are also embedded in the lower end portion of the footing concrete 18 at substantially equal intervals. A part of the main reinforcement 24 embedded in the lower end portion of the footing concrete 18 is arranged through a first plate 28A of a cross rib 28 described later.

  A moisture-proof sheet or the like may be appropriately laid between the footing concrete 18 and the ground 20. Further, the arrangement of the main reinforcing bars 24 and the shear reinforcing bars 26 embedded in the footing concrete 18 is not particularly limited. For example, the main reinforcing bars 24 may be arranged so as to intersect the X direction and the Y direction.

(Cross rib configuration)
Next, the cross rib 28 will be described. 3A, the cross rib 28 is provided below the lower flange portion 14C of the steel foundation beam 14, and a metal that supports the steel foundation beam 14 with a gap 34 between the ground 20 and the ground rib 20. As shown in FIG. It is a member. Further, as shown in FIG. 3B, the cross rib 28 includes a first plate 28A arranged in the X direction and a first plate extending in the Y direction from both sides of the central portion of the first plate 28A. The plate 28B is formed in a substantially cross shape in plan view.

  A base plate 38 is provided below the cross rib 28, and the cross rib 28 is joined to the upper surface of the base plate 38 by welding or the like. The base plate 38 is provided on a filler 40 such as mortar or grout disposed on the ground 20, and four anchor bolts 42 are inserted into the base plate 38 and the filler 40. Yes. The anchor bolts 42 are inserted into the four corners of the base plate 38, and nuts (double nuts) 44 are screwed onto the upper ends of the anchor bolts 42 and fastened. Furthermore, a fixing nut 46 is provided at the lower end portion of the anchor bolt 42 embedded in the ground 20.

  Further, as shown in FIG. 1, the cross rib 28 is provided at a position overlapping the central axis C of the pile 12 in an elevational view, and in this embodiment, the central axis C of the pile 12 in an elevational view. And the intersection of the first plate 28A and the first plate 28B overlap each other. Not limited to this, it is only necessary that at least a part of the cross rib 28 overlaps the central axis C of the pile 12 in an elevational view. For this reason, the intersection of the first plate 28 </ b> A and the first plate 28 </ b> B may be shifted left and right (X direction) with respect to the central axis C of the pile 12.

  Further, in the present embodiment, the configuration can be simplified by using the cross ribs 28 as compared with the case where a steel pipe or the like is used. However, the present invention is not limited to this, and a member that can transmit the load of the steel foundation beam 14 If so, the steel foundation beam 14 may be supported by another member. For example, it is good also as a structure which arrange | positions a square steel pipe, a round steel pipe, etc., and supports the steel frame foundation beam 14. FIG.

  In the present embodiment, the joint portions 30 of the four steel foundation beams 14 and the columns 16 are illustrated and described. However, the present invention is not limited thereto, and the joints of one or more steel foundation beams 14 and the columns 16 are illustrated. The pile foundation structure of the present invention may be applied to the portion 30.

(Function and effect)
Next, the effect | action and effect of the pile foundation structure 10 of this embodiment are demonstrated. According to the pile foundation structure 10 according to the present embodiment, the steel frame foundation beam 14 is supported with a gap 34 between the cross ribs 28 and the ground 20 so that the foundation 20 is excavated to bury the foundation beam. There is no need to do. That is, in order to place the footing concrete 22 on the pile head 12A, it is only necessary to excavate the range of the two-dot chain line L in FIG. Can be planned.

  Further, by providing the steel foundation beam 14 above the ground 20, it is possible to avoid contact between the steel foundation beam 14 and the ground 20, and to prevent the steel foundation beam 14 from being rusted, and to provide long-term reliability. Can be secured.

  Furthermore, since it is comprised so that a load may be transmitted from the joint part 30 to the four piles 12, the axial force which acts on the pillar 16 can be disperse | distributed and transmitted to the four piles 12. FIG. Moreover, the moment which acts on the pile 12 at the time of an earthquake can be processed with the footing concrete 18, and seismic performance can be ensured.

  Further, by embedding the joint portion 30 between the column 16 and the steel foundation beam 14 in the footing concrete 18, the height of the building can be increased as compared with the configuration in which the joint portion 30 is provided on the upper portion of the footing concrete 18. Can be suppressed.

  Furthermore, since it is only necessary that the joint portion 30 of the column 16 and the steel foundation beam 14 is provided in the region where the plurality of piles 12 are driven, for example, even when the column division with the existing building is different, An existing pile can be used for a part of the pile 12, and labor saving can be achieved. As a result, the degree of freedom in design can be improved.

  In the present embodiment, the moment acting on the pile 12 at the time of an earthquake is processed by the footing concrete 18. However, the present invention is not limited to this, and at least a part of the moment may be processed by the steel foundation beam 14. As an example in this case, if studs are formed on both surfaces of the web portion 14B of the steel foundation beam 14, the moment acting on the pile 12 is transmitted to the steel foundation beam 14 via the footing concrete 18, and the moment is applied to the steel foundation beam 14. Can be processed. In particular, by providing a stud appropriately in the web portion 14B in the vicinity of the reinforcing rib 32, the moment acting on the pile 12 during an earthquake can be processed with a couple of forces.

Second Embodiment
Next, the pile foundation structure 50 which concerns on 2nd Embodiment of this invention is demonstrated. In addition, the same code | symbol is attached | subjected about the structure similar to 1st Embodiment, and description is abbreviate | omitted suitably. As shown in FIG. 4, the pile foundation structure 50 of the present embodiment is different from the first embodiment in the number of piles 12 driven into the ground 20.

  Specifically, the two piles 12 are driven into the region near the joint portion 30 with an interval in the X direction. Each pile 12 is a steel pipe pile formed in a substantially cylindrical shape, and footing concrete 52 is placed on a pile head 12A of each pile 12. Further, a pillar 16 is provided between the two piles 12, and four steel foundation beams 14 are joined to a diaphragm 16A provided on the pillar 16 by welding or the like.

  Here, the steel foundation beam 14 connected to both sides in the X direction with respect to the column 16 is provided at a position overlapping the two piles 12 in a plan view. For this reason, the cross rib 28 (see FIG. 1) supporting the steel foundation beam 14 is disposed on the footing concrete 22.

  In the present embodiment, the pile 12 and the steel foundation beam 14 are provided at a position where they overlap in a plan view. However, the present invention is not limited to this. It is good. Alternatively, one pile 12 may be shifted by a predetermined distance upward (+ Y direction) in the figure, and the other pile 12 may be shifted by a predetermined distance downward (−Y direction) in the figure.

  According to the pile foundation structure 50 of this embodiment, when the weight of a building is comparatively small, the number of the piles 12 can be reduced rather than the pile foundation structure 10 of 1st Embodiment. Other operations are the same as in the first embodiment.

  As mentioned above, although 1st Embodiment of this invention and 2nd Embodiment were described, this invention is not limited to such embodiment, You may use embodiment and various modifications suitably, Needless to say, the present invention can be implemented in various modes without departing from the gist of the present invention. For example, the pile foundation structure 10 of the first embodiment may be applied to a part of the foundation of a building, and the pile foundation structure 50 of the second embodiment may be applied to the remaining part.

DESCRIPTION OF SYMBOLS 10 Pile foundation structure 12 Pile 12A Pile head 14 Steel foundation beam 16 Column 18 Footing concrete 20 Ground 22 Footing concrete 28 Cross rib 30 Joint part 50 Pile foundation structure 52 Footing concrete

Claims (1)

Footing concrete placed on the pile heads of multiple piles;
A steel foundation beam in which a joint with a column is embedded in the footing concrete;
I have a,
The footing concrete includes a plurality of first footing concretes placed on the pile heads of the plurality of piles, and a second footing concrete formed integrally with the first footing concrete and connecting the plurality of first footing concretes. And
A pile foundation structure in which a cross rib for supporting the steel foundation beam is provided at a position overlapping the central axis of the pile in an elevational view on the first footing concrete with a gap between the ground .

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