JP2017172310A - Anchor reinforcement connection metal fitting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anchor reinforcement connection metal fitting capable of reducing cost by reducing tensile force of an anchor reinforcement, by improving installation work of the anchor reinforcement to a precast pile, without reducing joining force between the precast pile and foundation concrete.SOLUTION: In an anchor reinforcement connection metal fitting 1, six sleeves 3 are respectively fixed to a predetermined position of an outer peripheral surface of a pair of curved plates 21 in a state of separating in parallel to the axis of a cylindrical ring body 2 via a pair of sandwiching plates 27. The pair of sandwiching plates 27 are welded in a state of expanding toward the curved plate 21 side so as to become a V shape in a plan view. The cylindrical ring body 2 is inserted into an upper end part of a precast pile 10, and after fastening those by a bolt 25 and a nut 26, an anchor reinforcement 30 is fixed to the sleeves 3.SELECTED DRAWING: Figure 1

Description

  The present invention provides a plurality of precast concrete piles, steel pipe piles, and other pile heads and foundation concrete that are rigidly joined to each other via anchor reinforcing bars such as anchor bolts and deformed reinforcing bars. The present invention relates to an anchor reinforcing bar connecting bracket for fixing an anchor reinforcing bar to a pile head in a standing state.

  The method of joining the pile and foundation concrete is roughly divided into a pile head rigid connection type and a pile head hinge connection type. In the rigid head connection of precast concrete piles, the balance between the compressive force bearing part of the foundation concrete at the joint with the foundation concrete and the tensile force by the anchor reinforcement when the pile head receives a bending moment during an earthquake These assumptions are schematically shown in FIGS. In the figure, the portion indicated by hatching is the compressive force bearing portion 60, and the black circle represents the anchor rebar 70 bearing the tensile force. These parts are also displayed in the same manner in other drawings. Due to the balance of force, the relationship of tensile force T of anchor reinforcing bar = compressive force C of concrete is established. However, in the precast concrete pile 10, the pile body 11 has a strength of 2 to 3 times or more of the concrete strength used for the foundation concrete 50, and the end plate 12 (steel plate is formed at the tip of the pile body 11. ) Is integrated, the surface of the pile head is in a highly rigid state, and the end surface of the pile head has a structure that does not allow bending deformation. Therefore, the assumption shown in FIG. 9 (b) does not occur, and the end of the pile head becomes the center point of rotation when receiving a bending moment due to an earthquake or the like as shown in FIG. End up. At this time, in the concrete on the side of the foundation concrete 50, the burden area of the compression force becomes extremely small, and as a result of intensively bearing the compression force, local compression failure occurs in the foundation concrete 50. As a result, the assumption of T = C is not established, and there is a problem that the stress transmission between the pile head and the foundation concrete does not go smoothly.

  On the other hand, the compressive-force bearing part in the steel pipe pile or steel pipe concrete pile with which the anchor reinforcement was joined to the outer peripheral surface of a steel pipe, and the actual rotation situation assumed at the time of an earthquake can be shown as FIG. Since both the steel pipe pile and the steel pipe concrete pile have a steel pipe at the outer peripheral portion, the rotation is performed at the end of the steel pipe having high rigidity. In the steel pipe concrete pile 80 shown in the drawing, the compressive force bearing area on the foundation concrete 50 side is a small concrete area corresponding to a part of the cross-sectional area of the steel pipe 81, so that the foundation concrete 50 is subjected to local crushing failure. This is not much different from the precast concrete pile 10 described above in that the stress transmission between the pile head and the foundation concrete at the joint does not go smoothly.

  Furthermore, in order to fix the pile head to the foundation concrete only with the precast concrete pile, it is necessary to embed a length of more than twice the pile diameter in the foundation concrete. This is not used for building foundation beams (foundation concrete) because the reinforcement on the concrete side is an obstacle. For this reason, in precast concrete piles, it is common to fix anchors by connecting anchor rebars to the pile heads (tops). As shown in FIG. 13, in the precast concrete pile 10, when the anchor rebar 30 is joined to the steel end plate 12 at the tip of the pile body 11, the top portion of the pile is previously placed at an accurate height position. Is a prerequisite. In pile construction, it is important to ensure that the pile reaches the hard ground, but in reality it is difficult to set the distance to the hard ground in the ground and the length of the pile accurately in advance. If the hard ground is shallower than expected, the pile head will be exposed more than necessary, but if the precast concrete pile is cut, the end plate will also be removed, so the anchor rebar 30 cannot be attached. It becomes. Moreover, in order to ensure sufficient anchoring strength to the foundation concrete by the anchor reinforcing bar 30, it is necessary to install the required strength of the pile itself and the required quantity of the anchor reinforcing bar 30 corresponding to the strength. However, the place which can be joined to the pile head is limited, and there is a room for improvement in workability such as the case where the anchor rebar 30 corresponding to the strength of the pile cannot be installed.

  On the other hand, in the case of steel pipe piles and steel pipe concrete piles, embedding the tip of the pile to the ground solid ground is the same as precast concrete piles, but the pile length is set to a predetermined length or more in advance. In addition, there is an advantage that the extra length can be cut after the pile is placed. In this type of ready-made pile 80, as shown in FIG. 14, the anchor rebar 30 is generally welded directly to the outer periphery of the steel pipe 81. This welding is an on-site work, and may be a welding work on a muddy soil due to rainwater or the like. In particular, the pile head on which the welding operation is performed is also a point in contact with the muddy soil. In such an operation, it is difficult to obtain a reliable dry state even if sufficient drying is performed in advance, so that moisture tends to appear as a weld defect in the welded metal. In addition, for the welding operator, the muddy state is not good, and the work becomes a harsh working environment because it becomes a downward-facing work in the middle waist, and improvement in workability is desired.

  In order to improve the workability problem of the conventional technology as described above, a pair of semicircular plates (arc-shaped plates) with a plurality of couplers welded to the outer peripheral surface are used on the side of the head of the ready-made pile. There has been proposed a technique in which a threaded reinforcing bar or a deformed reinforcing bar with a threaded end is screwed onto each coupler after being arranged in an annular shape and tightened with a bolt or nut or the like (Patent Document 1). Even in this case, the resistance to the bending moment when the anchor reinforcement is connected to the ready-made pile is the product (moment) of the distance from the outer peripheral edge of the ready-made pile to the anchor reinforcement and the resistance of the anchor reinforcement. In the above, it is advantageous in terms of yield strength to install the anchor rebar as far as possible in the radially outward direction from the outer peripheral surface of the ready-made pile. Also in terms of this tensile resistance, the method of Patent Document 1 in which anchor reinforcing bars are erected at an interval from the surface of a ready-made pile is advantageous in terms of yield strength compared to the method shown in FIG.

  However, in the method of Patent Document 1, since the distance from the outer peripheral end of the ready-made pile to the anchor reinforcing bar is determined by the thickness of the semicircular plate, a thick material is used to separate the distance, which is not economical. . Moreover, in such a case, even if a pair of semicircular plates are tightened with bolts and nuts, the semicircular plates are not easily deformed, and the pile itself has tolerances and is not necessarily a perfect circle. A close contact state cannot be obtained with respect to the pile. For this reason, there is a problem that when a tensile force is applied to the anchor reinforcing bar, a slip is likely to occur between the semicircular plate and the ready-made pile, leading to a decrease in the tensile resistance.

Japanese Patent No. 5008532

  The present invention was made in view of the problems of the prior art described above, and while increasing the joint yield strength and joint rigidity between the ready-made pile and the foundation concrete, it is possible to improve the attachment work of the anchor rebar to the ready-made pile, Another object of the present invention is to provide an anchor rebar connecting metal fitting that can be applied to a pile head cut by a high stop and has improved economy.

  As a means for solving the problems of the above prior art, in the anchor reinforcing bar connecting metal fitting of the present application, a plurality of curved plates are connected in a cylindrical shape via screw members, and the pile head outer peripheral surface of a prefabricated pile placed on the ground A fixed cylindrical ring body and a plurality of anchor reinforcing bars embedded in the foundation concrete are fixed at substantially equal angular intervals through a pair of clamping plates along the circumference of the cylindrical ring body. A feature is that a combination of a plurality of sleeves supported upward in the vertical direction at a position away from the outer peripheral surface of the ready-made pile is adopted as a basic configuration.

According to the above configuration, with respect to the bending moment acting on the pile head, the anchor reinforcing bar on one end side that receives tensile force, and the anchor reinforcing bar on the other end side that receives compression force at the position opposite to this anchor reinforcing bar. The distance between the parts, that is, the distance between the part that receives the tensile force and the part that receives the compressive force is increased by the amount of the pair of sandwiching plates interposed between the outer peripheral surfaces of the pile heads. For this reason, the tensile strength of the anchor rebar is reduced compared to conventional techniques such as precast concrete piles that stand upright on the upper surface of the end plate and steel pipe piles that are welded directly to the outer peripheral surface of the pile body. It is possible to select anchor rebars that are as small as the size, thereby reducing costs.
Furthermore, when the concrete is placed, the portion surrounded by a pair of clamping plates (gap) that supports the sleeve and the periphery of the sleeve are surely filled with concrete, thereby causing a burden of local compressive force. It can prevent compression failure of foundation concrete.
In addition, since the pair of clamping plates are joined to the outer peripheral surface of the cylindrical ring body, the rigidity of the cylindrical ring body is increased by the rib effect of the clamping plates, so that the thickness of each curved plate is reduced. Can lead to cost reduction.

  In the above configuration, a compression force bearing plate that is fixed with a nut or the like in a state where the anchor reinforcing bar is inserted can be provided on the upper portion of the sleeve. In this case, since the compressive force bearing plate also bears the tensile force of the anchor reinforcing bar, the burden of the tensile force of the anchor reinforcing bar is further reduced, so that a more economical anchor reinforcing bar can be applied.

  Furthermore, in the said structure, it is suitable that the distance between a sleeve and the ready-made pile outer peripheral surface shall be 2 times or more of the outer diameter of the anchor reinforcement used. In this case, the space between the portion receiving the tensile force and the portion receiving the compressive force is widened, and the above effect of reducing the tensile force of the anchor reinforcing bar is more effectively exhibited.

  Further, the pair of sandwiching plates may be fixed in a state where the distance between the plates is widened from the sleeve toward the cylindrical ring body. In this case, when placing the concrete foundation, it becomes easier to fill the space surrounded by the sandwiching plates, and more effectively prevent the foundation concrete compression failure due to the burden of local compression force. Can do.

  In the above configuration, the cylindrical ring body can be a pair of semicircular curved plates divided into two. In this case, since there are few connection parts by screw members, such as a volt | bolt and a nut, the working time required for the attachment to a pile head is shortened, and it leads to the improvement of workability. Furthermore, since the installation space for the sleeve can be afforded by a smaller number of connection points, it is convenient to increase the number of sleeves to cope with a large number of anchor reinforcing bars.

In the anchor rebar connecting metal fitting of the present invention, the following effects can be obtained by adopting the above configuration.
(1) With respect to the bending moment acting on the pile head, the distance between the part that receives the tensile force and the part that receives the compressive force is increased by the amount of interposition of the pair of clamping plates. Compared with this, the tensile force of the anchor reinforcement is reduced, and more economical anchor reinforcement can be selected, thereby reducing the cost. Furthermore, when a compression force bearing plate that is fixed by a nut or the like in a state where the anchor reinforcing bar is inserted is provided at the upper part of the sleeve, the tensile force of the anchor reinforcing bar is further reduced. Can be applied.
(2) When concrete is placed, the concrete between the pair of clamping plates that support the sleeve and the concrete around the sleeve are surely filled with concrete. Can be prevented.
(3) Since the pair of clamping plates are joined to the outer peripheral surface of the cylindrical ring body, the rigidity of the cylindrical ring body is increased by the rib effect of these plates. Thinning leads to cost reduction.
(4) Since the cylindrical ring body can be easily attached to the pile head with screw members such as bolts and nuts, and the anchor reinforcement can be easily attached using the sleeve, the anchor reinforcement for the pile head The connection work time can be shortened.
(5) After installation of ready-made piles, it can be installed at the desired height position from the top side or side of the pile head, so even if the pile head is cut by the high-end of the ready-made pile, it is applied without any problem be able to.

  (A)-(c) is the front view, side view, and top view of an anchor reinforcement connecting metal fitting which concern on 1st Embodiment of this invention, respectively.   It is explanatory drawing which shows the usage method of the anchor rebar connection metal fitting of FIG.   It is sectional drawing which shows the construction state of the anchor rebar connection metal fitting of FIG.   (A) and (b) are the forces of the compressive load bearing part of the foundation concrete and the tensile force by the anchor rebar when a bending moment is applied to the pile head to which the anchor rebar connection fitting of the present invention is attached, respectively. It is explanatory drawing which showed typically the assumption of the balance relationship.   It is explanatory drawing which shows the usage method of the anchor rebar connection metal fitting which concerns on 2nd Embodiment of this invention.   (A) And (b) is the top view and side view of a compression force burden plate which are used in 2nd Embodiment shown in FIG.   (A) And (b) is the compressive-force bearing part and anchor of a foundation concrete when a bending moment acts with respect to the pile head which attached the anchor reinforcing bar connecting bracket of 2nd Embodiment shown in FIG. 5, respectively. It is explanatory drawing which showed typically the assumption of the balance relationship of the force with the tensile force by a reinforcing bar.   It is sectional drawing which shows the construction state of the anchor rebar connection metal fitting which concerns on 2nd Embodiment of FIG.   (A) and (b) are respectively the compressive force bearing part when the bending moment is applied to the pile head in which the anchor rebar is connected to the end plate of the conventional precast concrete pile and the tensile force by the anchor rebar. It is explanatory drawing which showed typically the assumption of the balance relationship of force.   It is explanatory drawing which shows the actual rotation condition assumed at the time of the earthquake of the precast concrete pile of FIG.   It is explanatory drawing which showed typically the tensile force of an anchor reinforcement, and the compressive-force bearing part of foundation concrete when a bending moment acted on the pile head which welded the anchor reinforcement to the outer peripheral surface of the conventional steel pipe pile .   It is explanatory drawing which shows the actual rotation condition assumed at the time of the earthquake of the steel pipe pile of FIG.   It is a perspective view which shows the connection method of the anchor reinforcement in the conventional precast concrete pile.   It is a perspective view which shows the connection method of the anchor reinforcement in the conventional steel pipe pile.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is of course not limited to the illustrated embodiments, and the technical idea of the present invention, such as changes in the material, shape, quantity, and position of each component member, is described. Of course, various modifications are possible. (A)-(c) of Drawing 1 is a front view, a side view, and a top view of an anchor rebar connecting metal fitting concerning a 1st embodiment of the present invention, respectively. FIG. 2 shows how to use the anchor rebar connecting metal fitting, and FIG. 3 shows the construction state.

  As shown in FIGS. 1A to 1C, the anchor reinforcing bar connecting fitting 1 of the present invention has a configuration in which a plurality of sleeves 3 are provided around a cylindrical ring body 2. The cylindrical ring body 2 is composed of a pair of semicircular curved plates 21, and both end sides of each curved plate 21 are bent outward in the radial direction. A triangular reinforcing plate 23 is welded to the bent portions 22, and two bolt insertion holes 24 (see FIG. 2) are formed on the upper and lower sides, respectively, as screw members that are inserted in a state of facing each other. The pair of semicircular curved plates 21 can be connected and integrated into a cylindrical shape by the bolts 25 and the nuts 26. Note that the curved plate 21 is not limited to the semicircular two-part division, and it is of course possible to divide into three or more parts in consideration of the pile diameter and workability of the ready-made pile to be applied.

  Further, six sleeves 3 are fixed to predetermined positions on the outer peripheral surface of the curved plate 21 through a pair of clamping plates 27 in a state of being separated in parallel with the axis of the cylindrical ring body 2. In this case, as clearly shown in FIG. 1C, the pair of sandwiching plates 27 are welded so as to expand toward the curved plate 21 side, that is, in a V shape in plan view. In addition, the six sleeves 3 are firmly fixed at positions that are substantially equiangularly spaced in a state of being attached to a pile head of a ready-made pile to be described later. Further, the curvature of the pair of curved plates 21 is set so as to be substantially circular with a slight gap between the opposing bent portions 22 in a state where the pair of curved plates 21 is also attached to the pile head. Thereby, the adhesiveness with respect to the pile head of a pair of curved plate 21 increases, and the cylindrical ring body 2 can be firmly fastened to the pile head by tightening the cylindrical ring body 2 in the diameter reducing direction with the bolt 25 and the nut 26. As the bolt 25 used here, a high-strength bolt is suitable. Note that at least two sleeves 3 are attached to one curved plate 21. All the sleeves 3 attached to the curved plate 21 are arranged symmetrically with respect to the axis of the pile while the cylindrical ring body 2 is fixed to the pile, and at the same time the distance from the axis is It is particularly important to set them so that they are almost the same.

  Next, the usage method of the anchor rebar connection metal fitting 1 is demonstrated. As shown in FIG. 2, with a pair of curved plates 21 facing each other, a bolt 25 is inserted into a bolt insertion hole 24 of a bent portion 22, and a nut 26 is screwed into the bolt 25 to loosen the curved plates 21. Temporarily connect. And it inserts in the head of the ready-made pile 10 (precast concrete pile) from upper direction, and fastens it with the bolt 25 and the nut 26 in a predetermined height position. Finally, the anchor reinforcing bars 30 are inserted into the respective sleeves 3 and fixed with upper and lower nuts 31 and 32. Thereby, the plurality of anchor reinforcing bars 30 can be supported upward in the vertical direction with respect to the head of the ready-made pile 10 at a position away from the outer peripheral surface thereof. The anchor rebar 30 used here has a fixing plate 33 coupled to one end of a steel bar and a male threaded portion 34 formed on the other end. It should be noted that a threaded reinforcing bar can be used as the anchor reinforcing bar 30, and when the anchor reinforcing bar connecting fitting 1 is attached to the ready-made pile 10, the pair of curved plates 21 are separated from the ready-made pile 10 from the side. Alternatively, the bolt 25 and the nut 26 may be used for tightening.

  FIG. 3 is a cross-sectional view showing a construction state of the anchor reinforcing bar connecting fitting 1. After fixing the anchor rebar connecting bracket 1 of the present invention to the head of the ready-made pile 10 protruding from the surface of the ground 40 in the above procedure, the anchor rebar 30 is attached to each sleeve 3 and the foundation concrete 50 is driven. Set up. Thereby, the ready-made pile 10 and the foundation concrete 50 are integrated via the anchor reinforcement 30. In the figure, the anchor reinforcing bars 30 located on the left and right are separated from the outer peripheral surface of the ready-made pile 10 by a distance L by a pair of clamping plates 27, respectively. This distance L is preferably at least twice the outer diameter d of the anchor reinforcing bar 30. That is, with respect to the bending moment acting on the pile head, the distance between the anchor reinforcing bar 30 on one end side that receives a tensile force and the portion in the vicinity of the anchor reinforcing bar 30 on the other end side that receives a compressive force (FIG. 4B )), That is, the distance between the portion receiving the tensile force and the portion receiving the compressive force is increased by the amount of the pair of sandwiching plates 27 interposed. For this reason, the tensile force of the anchor rebar 30 will be reduced, the more economical anchor rebar selection will be possible, and it will lead to the cost reduction of pile head joining construction. Further, when the foundation concrete 50 is placed, the concrete is surely filled in the space 28 (see FIG. 1C) surrounded by the pair of sandwiching plates 27 that support the sleeve 3 and the sleeve 3. Compressive failure of the foundation concrete 50 due to a burden of local compressive force can be prevented.

  Furthermore, the load-bearing mechanism in the pile head joint structure using the anchor reinforcing bar connecting fitting 1 of the present invention will be described with reference to FIGS. (A) is the position of the compressive-force bearing part when a bending moment acts on the pile head which attached the anchor rebar connection metal fitting of this invention, (b) is explanatory drawing which showed each stress degree distribution typically. . In addition, the figure has shown the case where the anchor rebar 30 is eight. If the anchor rebar connecting metal fitting 1 of the present invention is used, the concrete is reliably filled between the pair of sandwiching plates 27 and around the sleeve 3 supporting the anchor rebar 30 when the foundation concrete 50 is placed. It becomes possible to secure the area of the compressive force bearing portion 60 (see FIG. 4A) with a compressive area substantially similar to the assumed stress state, and compressive failure of the foundation concrete 50 due to a local compressive force burden. Can be prevented. Further, since the distance J between the positions at which the tensile force T and the compressive force C act is longer than that in the prior art shown in FIGS. 5B and 8, the tensile force of the anchor reinforcing bar 30 is reduced. This makes it possible to select a more economical anchor.

  Next, an anchor reinforcing bar connecting bracket according to a second embodiment of the present invention will be described with reference to FIGS. In addition, about the same part as 1st Embodiment, it shows with the same code | symbol and the overlapping description is abbreviate | omitted. As shown in FIG. 5, in this embodiment, the lower end side of the anchor reinforcing bar 30 is inserted into the compressive force bearing plate 29, and the compressive force bearing plate 29 is fixed to the upper portion of the sleeve 3 with upper and lower nuts 31 and 32. There are features. As shown in FIG. 6, the compressive force bearing plate 29 used here has a disc shape with an insertion hole 29a formed at the center. According to the second embodiment, as shown in FIG. 7, since the compressive force is borne and the tensile force of the anchor rebar 30 is also borne, the load of the tensile force of the anchor rebar 30 is reduced, and a smaller diameter is provided. Can be used and is economical.

  The anchor rebar connecting metal fitting 1 according to the present invention can be applied to various ready-made foundation piles. Specific examples include PHC piles, PRC piles, concrete piles with shell steel pipes, steel pipe piles, and the like. In the anchor rebar connecting metal fitting 1 according to the present invention, it is fitted at an arbitrary height position of the pile head, tightened from the outside in the direction of reducing the diameter of the cylindrical ring body 2 with a screw member, and in pressure contact with the ready-made pile. It is to be fixed. This eliminates the need for machining the pile heads, and at the same time allows for easy and reliable mounting without being a skilled person, so that the connecting work of anchor reinforcing bars is greatly rationalized. In particular, in the installation work of the ready-made pile, there is an advantage that the anchor reinforcing bar connecting fitting 1 can be applied as it is even when the pile head is cut by a high stop.

  The anchor rebar connecting metal fitting of the present invention can easily and rigidly join the pile head of the pre-made pile and the foundation concrete with high anchoring strength, and can further reduce the cost. There is expected.

  1: Anchor rebar fitting, 2: Cylindrical ring body, 3: Sleeve, 10: Precast concrete pile, 21: Curved plate, 22: Bending part, 23: Reinforcement plate, 25: Bolt, 26: Nut, 27: Clamping Plate, 29: compressive force bearing plate, 30: anchor rebar, 40: ground, 50: foundation concrete, 60: compressive force bearing section, 80: steel pipe concrete pile

Claims (5)

  A plurality of curved plates are connected in a cylindrical shape via screw members, and are fixed to a pile head outer peripheral surface of a pre-made pile placed on the ground, and along the circumference of the cylindrical ring body, respectively. Fixed at approximately equiangular intervals via a pair of clamping plates, and supports the lower end side of a plurality of anchor rebars embedded in the foundation concrete upward in the vertical direction at a position away from the outer peripheral surface of the prefabricated pile An anchor reinforcing bar connecting bracket comprising a plurality of sleeves.   The anchor reinforcing bar connecting bracket according to claim 1, further comprising a compressive force bearing plate fixed to the upper portion of the sleeve in a state where the anchor reinforcing bar is inserted.   3. The anchor reinforcing bar connecting bracket according to claim 1, wherein a separation distance of the sleeve from the ready-made pile is twice or more an outer diameter of the anchor reinforcing bar.   4. The anchor reinforcing bar connecting bracket according to claim 1, wherein the pair of clamping plates are fixed to the cylindrical ring body in a state in which a gap is widened. 5.   The anchor reinforcing bar connecting bracket according to any one of claims 1 to 4, wherein the cylindrical ring body includes a pair of semicircular curved plates.

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