JP6027391B2 - Pile head joint structure - Google Patents

Description

  The present invention relates to a pile head joint structure in which a plurality of pile head rebar joint members are provided along a steel pipe outer peripheral surface of a pile head of a pile using a steel pipe such as a steel pipe concrete pile or a steel pipe pile.

  The pile and the footing (foundation concrete) are combined by fixing a plurality of pile head reinforcing bars provided on the pile head in the footing. In addition, regarding steel piles, steel pipe concrete piles and steel pipe piles, for which demand has been increasing in recent years, have a higher bending moment acting on the pile heads than other piles because the pile body has higher yield strength, and each pile head The tensile force generated in the reinforcing bar also increases.

  As a pile head joint structure such as these steel pipe concrete piles, it is common to weld the pile head rebar directly to the steel pipe outer peripheral surface of the pile head, but as mentioned above, the tensile force generated in the pile head rebar is large. It is difficult to employ large diameter reinforcing bars or high strength steel bars, which are feared for weldability. Therefore, many pile head reinforcing bars will be provided along the steel pipe outer peripheral surface of a pile head, and workability | operativity, such as welding and reinforcement, is bad.

  For this reason, many pile head joint structures in which a connecting member to which a pile head reinforcing bar is connected to one end side are welded to the outer peripheral surface of a steel pipe have been disclosed (see, for example, Patent Documents 1 to 3). Since these pile head joint structures provide pile head reinforcing bars at positions away from the steel pipe outer peripheral surface of the pile heads, the tensile force generated in the pile head reinforcing bars is reduced, and the number of pile head reinforcing bars can be reduced. Moreover, since it is not necessary to weld a pile head reinforcement directly to a steel pipe outer peripheral surface, there exists an effect that it becomes easy to employ | adopt the pile head reinforcement of a large diameter or a high strength material.

Japanese Patent Publication No. 03-054736 JP 2001-182079 A JP 2002-115248 A

  However, the pile head joint structures described in Patent Documents 1 to 3 have the following problems.

(1) Problems of the pile head joint structure described in Patent Document 1 (i) The flat plate is welded to the circumferential surface position on the steel pipe (pile) side from the center of the coupler (center of tensile force generated in the pile head rebar). Therefore, when a bending moment is applied to the pile head, stress is locally concentrated on the welded portion, and there is a concern about the destruction of the welded portion, which requires a larger amount of welding.
(Ii) Since the flat plate is welded to the outer peripheral surface of the steel pipe, when the bending moment is applied to the pile head, the height of the flat plate (length in the vertical direction) is used to prevent the steel pipe itself from being deformed out of plane. ) Must be increased to increase the welding length.
(Iii) Since the flat plate bears stress, it is necessary to increase the thickness of the flat plate in order to prevent the flat plate itself from being deformed out of plane, and defects occur when welding to a steel pipe with a thin plate thickness. easy. Further, when a shearing force in the out-of-plane direction acts on the flat plate, the welding portion between the flat plate and the steel pipe is also loaded with a force such as bending, so that a larger amount of welding is required.
(Iv) When a large diameter or high strength material is used for the pile head rebar, the joint (weld) proof strength that can sufficiently transmit stress to the proof strength of the pile head rebar is required. The weld length with the outer peripheral surface becomes longer, and it is necessary to increase the overall length of the coupler and the height of the flat plate.

(2) Problems with the pile head joint structures described in Patent Documents 2 and 3 (i) When a bending moment is applied to the pile head, the tensile and compressive forces generated in the pile head rebar are the bearing plates and nuts (washers). In order to act on only the upper or lower surface of the connecting member via the joint, stress is locally concentrated on the welded portion between the connecting member and the steel pipe, and there is a concern about the destruction of the welded portion, in order to prevent the destruction. Requires more welding.
(Ii) Since the concrete or solidification material filled inside the connecting member is in contact with the pile head reinforcement, when a tensile force is generated in the pile head reinforcement, the surrounding concrete, etc. in contact with it is split. May occur, which may adversely affect the deformation of the connecting member itself and the welded portion with the steel pipe. That is, there is a possibility that the restraining effect by concrete or the like is reduced.

  Therefore, the present invention has been made paying attention to such problems, ensuring a predetermined joint strength without increasing the welding amount of the joint portion (welded portion) in the steel pipe or connecting member more than necessary, An object of the present invention is to provide a pile head joint structure capable of efficiently performing stress transmission between a pile and a footing.

In order to achieve the above object, a pile head joint structure according to the present invention is a pile head joint structure in which a plurality of pile head reinforcing bar joint members are provided along the steel pipe outer peripheral surface of a pile head in a steel pipe concrete pile or a steel pipe pile. Te, the pile head rebar bonding member includes a cylindrical body pile cap rebar are inserted, the one end side are provided in a state sandwiching the tubular body from both sides thereof, the other end the steel pipe outer peripheral surface A pair of connection plates welded to each other , each of the pair of connection plates being independent and having a shape in which the lower end portion gradually widens downward from the cylindrical body toward the steel pipe. The cylindrical body is formed with a through-hole penetrating from the upper part to the lower part where the lower end part of the pile head reinforcing bar is inserted, and the lower end part of the pile head reinforcing bar is a through hole of the cylindrical body Can protrude from the lower part and the lower ends of the pair of connecting plates Characterized in that it is formed in.
Here, one end of the pair of connection plates, extends beyond the longitudinal center line of the tubular body, wherein the pair of connection plates, respectively, and the outer peripheral surface of the tubular body and its inner surface by the the steel pipe side and the steel pipe side forms a corner in two places opposite, it is preferable to weld them all corners.
Moreover, it is good for the said cylindrical body to form the internal thread part screwed together in the internal thread part of the said pile head reinforcement.

In the pile head joint structure according to the present invention, the cylindrical body into which the pile head rebar is inserted and the one end side are provided in such a state that the cylindrical body is sandwiched from both sides, and the other end side is welded to the outer peripheral surface of the steel pipe. Since the pile head rebar joint member is composed of a pair of connected plates, a predetermined joint strength can be ensured without increasing the welding amount of the joint (welded part) in the steel pipe or pile head rebar joint member more than necessary. The stress can be transmitted efficiently between the pile and the footing.
In particular, in the pile head joint structure according to the present invention, each of the pair of connection plates is independent, and is formed in a shape in which the lower end portion gradually widens downward as it goes from the tubular body to the steel pipe. The through-hole penetrating from the upper part to the lower part where the lower end part of the pile head reinforcing bar is inserted is formed, the lower end part of the pile head reinforcing bar is the lower part of the through hole of the cylindrical body, and the pair of connections Since it is formed so as to be able to protrude from the lower end of the plate, it is possible to secure a work space for attaching the lower nut while securing the weld length between the connection plate and the steel pipe. As a result, the amount of excavated soil at the pile head can be reduced, and workability is further improved.

It is a front view which shows an example of the pile head junction structure which concerns on this invention. It is a left view of the pile head junction structure. It is an AA line sectional view in the pile head junction structure. It is an enlarged plan view of the pile head joint structure. It is an enlarged plan view of a pile head joint structure using another cylindrical body. Furthermore, it is an enlarged plan view of the pile head joint structure using another cylindrical body. It is a front view which shows the difference in the amount of excavated soil by the difference in the shape of a connection board. It is an enlarged plan view which shows the other example of a pile head junction structure. It is an enlarged plan view which shows the other example of a pile head junction structure. It is an enlarged plan view which shows the other example of a pile head junction structure.

Next, an embodiment of a pile head joint structure according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, this pile head joint structure is along the steel pipe outer peripheral surface of the pile head in the pile 1 using the steel pipe 11 such as a steel pipe concrete pile (SC pile) or a steel pipe pile (S pile). A plurality of pile head rebar joint members 2 are provided at appropriate intervals such as 60 degrees and 90 degrees, and the pile head rebar joint members 2 are inserted into the pile head rebar joint members 2 and screwed together. Is configured to do. The pile head rebar 3 joins the pile 1 and the foundation concrete by being inserted and fixed in a footing of foundation concrete (not shown), and here, as an example, a threaded joint (deformed bar) is used. In FIG. 1 to FIG. 3, for convenience of explanation, only one pile head reinforcing member 2 is not shown in the pile head of the pile 1, but actually, at an appropriate interval along the outer peripheral surface of the steel pipe 11. A plurality are provided.

  The pile head reinforcing bar joining member 2 includes a cylindrical body 21 and a pair of connection plates 22 and 22. The cylindrical body 21 is inserted with the male thread portion 31 of the pile head rebar 3, and the outer peripheral surface is hexagonal as shown in FIG. 4 and the like, while the inner peripheral surface thereof has the pile head rebar 3 of the pile head rebar 3. A female screw portion 21 a that is screwed into the male screw portion 31 is formed. Here, if the cylindrical body 21 having the female screw portion 21a formed therein is used, when a bending moment is applied to the pile head, a tensile force or a compressive force generated in the pile head rebar 3 is generated. The pair of connecting plates 22, 22 act through the entire length in the vertical direction through the cylindrical body 21, and stress is locally concentrated on the welded portion 53 between the connecting plates 22, 22 and the steel pipe 11. It is suitable because it does not. In addition, even if it is the cylindrical body in which the internal thread part 21a mentioned later is not formed in the inside, the tensile force and compression force which arise in the pile head reinforcement 3 are not only the upper surface or lower surface of the connection plates 22 and 22, but cylindrical. Since it also acts on the body, local concentration of stress on the welded portion 53 can be suppressed.

  The pair of connection plates 22, 22 are welded so that one end side (tubular body 21 side) sandwiches the cylindrical body 21 from both sides, and the other end side (steel pipe 11 side) is the steel pipe 11. It is welded to the outer peripheral surface. Here, as shown in FIG. 1 and FIG. 3, the pair of connection plates 22, 22 has a shape in which the lower end portion gradually widens downward as it goes from the tubular body 21 to the steel pipe 11. By this, the welding length required for the stress transmission to the cylindrical body 21 and the steel pipe 11 is ensured. Further, one end side of the pair of connection plates 22 and 22 exceeds the center line 21c in the longitudinal direction of the cylindrical body 21, and is at least the outer peripheral surface of the cylindrical body 21 from the steel pipe 11, that is, a hexagonal shape in FIG. The cylindrical body 21 extends beyond the farthest corner 21b. That is, this pile head reinforcing bar joining member 2 is configured such that the farthest-angle portion 21b of the cylindrical body 21 does not protrude from the pair of connection plates 22 and 22 when viewed from the front as shown in FIG. .

  As shown in FIG. 4 and the like, the pair of connection plates 22 and 22 and the cylindrical body 21 are joined by the inner surface of the pair of connection plates 22 and 22 and the outer peripheral surface of the hexagonal cylindrical body 21. Two portions, ie, a corner on the steel pipe 11 side to be formed and a corner (cham) on the side opposite to the steel pipe 11 side are welded by fillet welding or the like. That is, the cylindrical body 21 is welded at four locations in a state where both sides thereof are sandwiched between the pair of connection plates 22 and 22. In the figure, 51 and 52 at two locations are welds between the pair of connection plates 22 and 22 and the cylindrical body 21.

  Therefore, according to the pile head joining structure of the embodiment using this pile head rebar joining member 2, the cylindrical body 21 is joined to the steel pipe 11 using the two connection plates 22, 22. Compared with the prior art of Patent Document 1 in which a coupler coupled to the head reinforcing bar is welded to the steel pipe with a single flat plate, when the stress is transmitted from the foundation concrete to the steel pipe 11 via the pile head reinforcing bar 3, the steel pipe 11 is faced. The outward bending force is distributed to the two connection plates 22, 22, so that a strong joint with both strength and rigidity can be formed without increasing the height of the flat plate.

  Moreover, in this pile head reinforcement joining member 2, since a pair of connection plates 22 and 22 are attached in parallel, it becomes easy to attach a pair of connection plates 22 and 22 perpendicularly with respect to the pile 1 at the time of construction. The effect is also obtained. Moreover, compared with the prior art of patent document 1 which welds one flat plate and a coupler, since this pile head reinforcement joining member 2 uses the two connection plates 22 and 22 and the cylindrical body 21, it is connected. It is possible to reduce the plate thickness of the plates 22 and 22, and to secure a welded portion that is easy to weld and of good quality, and is harmful due to bending as in the U-shaped plate disclosed in Patent Document 2. A plasticized portion is not provided in the pile head reinforcing bar joining member 2. Moreover, as shown in FIG. 4 etc., since the outer side surface of the cylindrical body 21 is a hexagon, a groove | channel is naturally formed in the corner (cham) between the inner side surfaces of a pair of connection plates 22 and 22, While welding work becomes easy, the quality pile head reinforcement joining member 2 can be manufactured.

  Further, as shown in FIG. 4 and the like, the pair of connection plates 22 and 22 and the cylindrical body 21 are welded at two welded portions 51 and 52, respectively, and are welded at a total of four locations. More welding lengths can be obtained as compared with the prior art of Patent Document 1 in which one flat plate and a coupler are welded. Therefore, it is possible to shorten the length in the vertical direction of the tubular body 21 and the connection plates 22 and 22 of the portion welded thereto while securing the weld length to the steel pipe 11.

  Furthermore, in this pile head reinforcement joining member 2, when foundation concrete is laid, the concrete is clogged in the space (gap) 23 between the pair of connection plates 22 and 22 and the pile 1 as shown in FIG. Become. Therefore, when stress is transmitted to the pair of connection plates 22 and 22, the pair of connection plates 22 and 22 integrally resist in a state in which the concrete filled in the space 23 is constrained. The reinforcing bar joining member 2 and the steel pipe 11 are not easily deformed out of plane. In addition, the concrete filled in the space 23 between the pair of connection plates 22 and 22 and the steel pipe 11 is not directly in contact with the pile head rebar 3 that is a fixing body by the tubular body 21, and therefore is pulled to the pile head rebar 3. Even if force is generated, splitting does not occur, and there is no fear that the constraining effect by concrete is reduced.

  Moreover, in this pile head rebar joining member 2, not only four places are welded between a pair of connection plates 22 and 22 and the hexagonal cylindrical body 21, but two locations in each of the connection plates 22 and 22, respectively. As shown in FIG. 4, the welded portions 51 and 52 are provided at positions symmetrical with respect to a plane perpendicular to the connection plates 22 and 22 through the center line 21 c in the longitudinal direction of the cylindrical body 21. . Therefore, with respect to the tensile force acting on the pile head rebar 11 and the tubular body 21, the two welded portions 51 and 52 in each of the connection plates 22 and 22 sandwiching the center line 21c act as reaction forces, respectively. Become. That is, not only the welded portions 52 and 52 welded from the center line 21c to the circumferential surface position on the steel pipe side, but also the welded portions 51 and 51 on the opposite side of the steel pipe side that are in a line-symmetrical position with respect to those positions. Therefore, even if a bending moment acts on the pile head, stress is not locally concentrated on the welded parts 52, 52, and the expected welding strength can be sufficiently exhibited.

  Further, the other end side of each of the pair of connection plates 22 and 22 is grooved as shown in FIG. 4 and the like, and melts an outer corner formed with the outer peripheral surface of the steel pipe 11. The welded portion 53 is formed by welding by lap welding. In addition, since the outer peripheral surface of the steel pipe 11 is curved, the groove processing on the other end side of the connection plates 22 and 22 may be omitted. Further, in each of the pair of connection plates 22 and 22, two outer corners (filled corners) and inner corners (filled corners) formed between the outer peripheral surfaces of the steel pipe 11 are welded by fillet welding or the like. Also good.

  In the above description, the cylindrical body 21 is described as having a hexagonal outer peripheral surface and a female screw portion 21a formed on the inner peripheral surface thereof as shown in FIGS. In the present invention, not limited to this, as shown in FIG. 5, a cylindrical body 21 ′ having a circular outer peripheral surface and a female screw portion 21 a ′ formed on the inner peripheral surface thereof may be used, as shown in FIG. 6. As described above, the outer peripheral surface is a circular shape or a polygonal shape such as a hexagon like the cylindrical body 21 shown in FIGS. 1 to 4, and the inner peripheral surface of the cylindrical body 21 ″ not formed with a female thread portion. However, in the case of the cylindrical body 21 ″ shown in FIG. 6, since the internal thread portion is not formed on the inner peripheral surface, when connecting the pile head reinforcing bars 3, as shown in FIG. It is necessary to tighten with the nuts 41 and 42 above and below the body 21 ". Therefore, than the rectangular connecting plate 22 'in the front view shown on the right side in FIG. In the front view shown on the left side in FIG. 7, the connecting plate 22 whose lower end portion gradually widens downward as the lower end portion moves from the tubular body 21 ″ to the steel pipe 11 has a longer welding length between the connecting plate 22 and the steel pipe 11. While securing, it is possible to secure an installation work space for the lower nut 42. As a result, the amount of excavated soil at the pile head can be reduced, and workability is further improved. In FIG. 7, a pile head reinforcing bar 3 ′ having a deformed reinforcing bar with an outer peripheral surface is used as the pile head reinforcing bar.

  Moreover, as shown in FIG. 8, you may perform penetration welding etc. by providing the backing metal 24 and 24 in the junction part between a pair of connection plates 22 and 22 and the steel pipe 11, respectively. By performing penetration welding using the backing metal 24, 24, it is possible to manufacture the pile head rebar joint member 2 having good welding quality. In addition, as shown in FIG. 8, a pair of connection plates 22 and 22 and backing metal 24 and 24 may be fillet welded and further welded portions 54 and 54 may be provided. In this case, the cylindrical body is not limited to the cylindrical body 21 ″ shown in FIG. 8, but the cylindrical body 21 shown in FIGS. 1 to 4 and the cylindrical body 21 ′ shown in FIG. 5 can also be used. The same applies to FIGS. 9 and 10 described later.

  Moreover, in this invention, as shown in FIGS. 1-8, it is not necessary for the one end part of connection board 22,22 'to extend to the farthest end of cylindrical body 21,21', 21 '', and a connection board For example, as shown in FIG. 9, the center line 21c ″ of the cylindrical body 21 ″ is sufficient because it is sufficient that the 22 and 22 ′ can be joined or integrally formed with the cylindrical bodies 21, 21 ′ and 21 ″ sandwiched from both sides. It only has to extend to the vicinity.

  Further, instead of the flat connection plates 22 and 22 ′ as shown in FIGS. 1 to 9, a pair of curved connection plates 22 ″ and 22 ″ can be used as shown in FIG. 10. By using a pair of curved connection plates 22 ″ and 22 ″, a groove is naturally formed between the other end side of the connection plates 22 ″ and 22 ″ and the outer peripheral surface of the steel pipe 11. Processing time can be saved and workability is improved. Further, since the distance between the welds of the other end portions of the pair of connection plates 22 ″ and 22 ″ with respect to the steel pipe 11 is increased, the resistance to the out-of-plane deformation of the steel pipe 11 is increased also in this respect.

  DESCRIPTION OF SYMBOLS 1 ... Pile, 11 ... Steel pipe, 2, 2 '... Pile head reinforcement member 21, 21, 21', 21 "... Cylindrical body, 21a, 21a '... Female thread part, 22, 22', 22" ... Connection board 3, 3 '... Pile head rebar, 31 ... Male thread part, 51, 52, 53, 54 ... Welded part.

Claims (3)

A pile head joint structure in which a plurality of pile head rebar joint members are provided along the steel pipe outer peripheral surface of the pile head in a steel pipe concrete pile or a steel pipe pile,
The pile rebar bonding member is welded to the tubular body pile cap rebar are inserted, the one end side are provided in a state sandwiching the tubular body from both sides, the other end to the steel pipe outer peripheral surface A pair of connecting plates ,
Each of the pair of connection plates is independent and is formed in a shape in which a lower end portion gradually widens downward as it goes from the cylindrical body to the steel pipe,
The cylindrical body is formed with a through-hole penetrating from the upper part to the lower part where the lower end part of the pile head reinforcing bar is inserted, and the lower end part of the pile head reinforcing bar is the lower part of the through hole of the cylindrical body, and The pile head joint structure is formed so as to be able to protrude from the lower end portions of the pair of connection plates . In the pile head joint structure according to claim 1,
One end side of the pair of connection plates, extends beyond the longitudinal center line of the tubular body, wherein the pair of connection plates, respectively, wherein the an outer peripheral surface of the tubular body and its inner surface the steel pipe the side and the steel pipe side forms a corner at two locations opposite pile head joint, characterized in that welding them all corners structure. In the pile head joint structure according to claim 1 or claim 2,
The cylindrical body, pile joint structure, characterized in that the female thread portion screwed to the male screw portion of the pile head reinforcement therein is formed.

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