JP2018162654A - Pile head joint part design method, construction method, design drawing, specification for pile head anchor reinforcement, and pile head anchor reinforcement attachment position checking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile head joint part design method and the like, for making a bending moment generated at a pile head be equal to or lower than an allowable bending moment of a pile head joint part determined by considering attachment intervals of anchor reinforcements even when the intervals of the anchor reinforcements are uneven in the circumferential direction of the pile head.SOLUTION: A pile head joint part design method includes: an allowable bending moment data preparation step of preparing allowable bending moment data corresponding to an allowable bending moment of a pile head joint part; a generated bending moment calculation step of calculating a generated bending moment Mo generated at the pile head; and a specification determination step of determining a specification for the pile head joint part so that the generated bending moment Mo is equal to or lower than the allowable bending moment data. Allowable bending moment data in the case that attachment intervals of a plurality of anchor reinforcements in the circumferential direction of the pile head are uneven is prepared. As an attachment condition for the plurality of anchor reinforcements, an allowable deviation amount from reference positions for attachment positions of the plurality of anchor reinforcements to the pile head part is determined, where the reference positions are attachment positions in the case that the plurality of anchor reinforcements are attached at equal intervals in the circumferential direction of the pile head.SELECTED DRAWING: Figure 16

Description

  The present disclosure relates to a design method of a pile head joint, a manufacturing method, a design drawing, a specification sheet for a pile head fixing bar, and an apparatus for confirming the mounting position of the pile head fixing bar.

  The pile foundation that supports the superstructure generally has a plurality of piles and a foundation concrete portion such as a pile cap or a footing that is provided so as to surround the upper end portion (pile head) of the pile. In order to reinforce the connection between the pile head and the foundation concrete part, for example, as disclosed in Patent Document 1, a joining member and a reinforcing bar (fixing bar) are used. A pile head, a joining member, a reinforcing bar, and a foundation concrete part constitute a pile head joined part.

More specifically, in the pile head joint portion disclosed in Patent Document 1, a plurality of joint members are attached to the outer peripheral surface of the pile head at intervals in the circumferential direction. The joining member has a lower plate portion and an upper plate portion that are separated from each other in the axial direction of the pile head portion, and a screw portion of a reinforcing bar is coupled to the lower plate portion of the joining member. The shaft portion of the reinforcing bar extends through the insertion portion of the upper plate portion of the joining member and protrudes upward from the end surface of the pile head.
In the pile head joint portion disclosed in Patent Document 1, the foundation concrete portion pushes the upper plate portion upward with a force, and even if the screw portion is formed on the reinforcing bar by screw machining, the pile head portion and the foundation The joint of the concrete part can be effectively reinforced.

  In addition, the structure of a pile head junction part is not limited to what was described in patent document 1, and there exists a thing etc. in which the reinforcing bar is welded directly to the pile head.

JP 2015-34458 A

Conventionally, the design and construction of a pile head joint has been performed on the premise that the installation intervals (arrangement intervals) of a plurality of fixing bars in the circumferential direction of the pile head are equal intervals (excluding errors during construction). It was.
However, at the construction site of the pile foundation, the balance between the pile head joint and the reinforcement of the superstructure located above the pile head joint and the reinforcement of the foundation beam placed horizontally to the pile head joint In some cases, an overcrowded reinforcement is generated in the case 1, and it becomes difficult to attach the fixing muscles at equal intervals. In addition, at the design stage, even if the pile cores can be arranged at equal intervals, there is a variation in pile core accuracy after the pile construction, and when the pile cores are slightly displaced, the fixing bars may not be arranged at equal intervals.

  As described above, in the case where the fixing bars are not evenly spaced, anisotropy occurs in the bending strength of the pile head joint, and the bending strength of the pile head joint is different from the design value. Therefore, even in such a case, when designing the pile head joint, the allowable bending moment should be calculated in consideration of the non-uniformity of the fixed reinforcement mounting interval without limiting it to an equal interval. It is desirable that the generated bending moment be equal to or less than the allowable bending moment of the pile head joint considering the mounting interval of anchoring bars.

  On the other hand, when constructing the pile head joint, the worker who installs the anchor reinforcement works based on documents such as pile maps and specification special notes (hereinafter also simply referred to as design drawings). There is no description about the fixing muscle mounting interval. For this reason, the worker proceeds with the fixing muscle attaching operation on the premise of equal intervals. Under such circumstances, when it is impossible to attach the fixing muscles at equal intervals, the operator must ask for instructions from the person in charge at the site, and the fixing muscle attaching operation becomes complicated.

  In addition, as technical data on pile head joints, specifications for anchors for pile heads with the pile diameter and the number of anchors are published on the website such as Pamplet and the Internet. There is no description up to the allowable deviation from the equidistant mounting positions (reference positions). If the maximum installation interval and allowable deviation of the anchor bars are described in the specifications of the anchor bars for pile heads, the designers and installers of the pile head joints will be able to Design and construction can be performed easily.

  On the other hand, even if the operator who installs the fixing bar knows the allowable deviation amount from the reference position of the fixing bar attachment position, the deviation amount from the reference position of the fixing position is measured for each fixing bar. It is cumbersome to install while measuring using equipment.

In view of the above circumstances, the object of at least one embodiment of the present invention is to determine the generated bending moment of the pile head even if the spacing of the fixing muscle is uneven in the circumferential direction of the pile head. It is providing the design method of the pile head joint which can be made below into the allowable bending moment of the pile head joint which considered.
In addition, the object of at least one embodiment of the present invention is to consider the generated bending moment of the pile head in consideration of the installation interval of the fixing bars even if the spacing of the fixing bars is not uniform in the circumferential direction of the pile head. Another object of the present invention is to provide a method for constructing a pile head joint that can be made below the allowable bending moment of the pile head joint.
In addition, the object of at least one embodiment of the present invention is to consider the generated bending moment of the pile head in consideration of the installation interval of the fixing bars even if the spacing of the fixing bars is not uniform in the circumferential direction of the pile head. Another object of the present invention is to provide a design drawing of a pile head joint that can be made below the allowable bending moment of the pile head joint.
In addition, the object of at least one embodiment of the present invention is to consider the generated bending moment of the pile head in consideration of the installation interval of the fixing bars even if the spacing of the fixing bars is not uniform in the circumferential direction of the pile head. It is intended to provide a specification sheet for anchors for pile heads that can be made below the allowable bending moment of the pile head joint.
The object of at least one embodiment of the present invention is to allow the generated bending moment of the pile head to take into account the installation interval of the fixing bars even if the spacing of the fixing bars is not uniform in the circumferential direction of the pile head. Another object of the present invention is to provide an apparatus for confirming an attachment position of a fixing head for a pile head, which can easily attach a fixing muscle so as to be equal to or less than an allowable bending moment of a pile head joint.

(1) A method for designing a pile head joint according to at least one embodiment of the present invention includes:
Pile head joint design comprising a pile head, a plurality of anchoring bars arranged around the pile head, and a foundation concrete part constituted by concrete surrounding the pile head and the plurality of anchoring bars In the method
An allowable bending moment data preparation step of preparing allowable bending moment data corresponding to the allowable bending moment of the pile head joint,
A generated bending moment calculating step for calculating a generated bending moment generated in the pile head; and
A specification determining step for determining the specifications of the pile head joint so that the generated bending moment is equal to or less than the allowable bending moment data;
With
In the permissible bending moment data preparation step, prepare permissible bending moment data when the mounting intervals of the plurality of fixing bars in the circumferential direction of the pile head are non-uniform,
In the specification determining step, as the mounting condition of the plurality of fixing bars, when the mounting positions when the plurality of fixing bars are mounted at equal intervals in the circumferential direction of the pile head are used as the reference position, An allowable deviation amount of the attachment positions of the plurality of fixing muscles with respect to the head from the reference position is determined.

According to the above configuration (1), by preparing the allowable bending moment data corresponding to the allowable bending moment when the mounting intervals of the plurality of fixing bars in the circumferential direction of the pile head are non-uniform, Even if the mounting interval is not uniform, the specifications of the pile head joint should be adjusted so that the bending moment generated at the pile head will be less than the allowable bending moment of the pile head joint taking into account the anchor spacing. Can be determined.
In the specification determining step, the allowable deviation from the reference position, which is an equidistant mounting position, is determined as the fixing streak mounting condition, and the fixing determined in the specification determining step is determined when the fixing streak is placed. If the mounting conditions of the bars are observed, the bending moment generated at the pile head can be ensured to be less than or equal to the allowable bending moment of the pile head joint in consideration of the mounting interval of the fixing bars.

(2) In some embodiments, in the configuration (1),
In the specification determining step, the allowable deviation amount is determined in consideration of a deviation direction of each of the fixing stripes as an attachment condition of the plurality of fixing stripes.
When a common allowable deviation amount is determined for the attachment positions of a plurality of fixing bars, the allowable bending moment changes depending on the combination of the deviation directions from the reference position.
In this regard, according to the configuration (2), the allowable deviation amount can be accurately determined by determining the allowable deviation amount in consideration of the deviation direction.

(3) In some embodiments, in the configuration (1) or (2),
In the specification determining step, the allowable bending moment data of the pile head joint when the mounting intervals of the plurality of fixing bars are uneven is the allowable bending when the mounting intervals of the plurality of fixing bars are equal. The specifications of the pile head joint are determined so as to be a predetermined ratio or more compared to the moment.

  According to the configuration (3), in the specification determination step, the allowable bending moment of the pile head joint when the fixing interval between the plurality of fixing bars is non-uniform, the mounting interval between the plurality of fixing bars is equal. Since the specifications of the pile head joints are determined so that the ratio exceeds the predetermined bending moment, the allowable bending moment of the pile head joints taking into account the installation interval of the anchor bars is too small. This can be prevented.

(4) In some embodiments, in any one of the configurations (1) to (3),
The allowable bending moment data preparation step includes a database access step of accessing a database in which the mounting intervals of the plurality of fixing bars and the allowable bending moment of the pile head joint are stored in association with each other,
In the allowable bending moment data preparation step, the allowable bending moment data is selected from the database.

  According to the above configuration (4), by preparing in advance a database in which the mounting intervals of the plurality of fixing bars and the allowable bending moment of the pile head joint are associated with each other, the mounting intervals of the plurality of fixing bars can be reduced. Even in the case of non-uniformity, it is possible to easily prepare the allowable bending moment data of the pile head joint in consideration of the attachment interval of the fixing bars.

(5) In some embodiments, in any one of the configurations (1) to (3),
A ratio for preparing a ratio of an allowable bending moment when the mounting intervals of the plurality of fixing bars are not uniform with respect to an allowable bending moment when the mounting intervals of the plurality of fixing bars are equal intervals under a predetermined axial force A preparation process,
In the allowable bending moment data preparation step, the allowable bending moment data is prepared by multiplying the allowable bending moment when the mounting intervals of the plurality of fixing bars are equal intervals by the ratio.

  According to the configuration (5), the allowable bending moment data can be easily prepared by multiplying the allowable bending moment of the pile head joint by the ratio prepared in advance.

(6) In some embodiments, in any one of the above configurations (1) to (5),
In the allowable bending moment data preparation step, as the allowable bending moment data, allowable bending moment data considering the side resistance of the pile head is prepared.
Normally, the side resistance of the pile head is not taken into account when calculating the allowable bending moment data. In particular, when using the main bar fixing method (the main fixing method using the fixing bar), the side resistance of the pile head is not taken into consideration. However, when a bending moment acts on the pile head, the side resistance of the pile head actually occurs and functions as a resistance to the bending moment of the pile head. For this reason, it is reasonable to consider the side resistance of the pile head as part of the allowable bending moment.
Therefore, according to the configuration (6), when the fixing bars are not evenly spaced, by preparing the allowable bending moment data in consideration of the side resistance of the pile head, an allowable bending moment having an appropriate size is prepared. Data can be prepared.

(7) In some embodiments, in the configuration (6),
In the specification determining step, the pile may be set such that the allowable bending moment data is equal to or greater than the allowable bending moment when the mounting intervals of the plurality of fixing bars are equal and the lateral resistance of the pile head is not considered. Determine the head joint specifications.
According to the above configuration (7), the pile head joint portion is set such that the allowable bending moment data is equal to or greater than the allowable bending moment when the mounting intervals of the plurality of fixing bars are equal and the lateral resistance of the pile head is not considered. Therefore, even when the mounting intervals of the plurality of fixing bars are non-uniform, it is possible to realize an allowable bending moment having a desired size.
Note that the side resistance of the pile head depends on, for example, the embedded length of the pile head relative to the foundation concrete portion, and can be increased by increasing the embedded length.

(8) The construction method of the pile head joint according to at least one embodiment of the present invention is as follows:
Construction of a pile head joint comprising a pile head, a plurality of anchoring bars arranged around the pile head, and a foundation concrete portion constituted by concrete surrounding the pile head and the plurality of anchoring bars In the method
Each of the plurality of fixing muscles with respect to the pile head when the attachment positions of the plurality of fixing muscles when the plurality of fixing muscles are attached at equal intervals in the circumferential direction of the pile head The plurality of fixing stripes are attached so that the amount of deviation of the attachment position from the reference position is equal to or less than a predetermined allowable deviation amount.

  According to the above configuration (8), the pile head is attached by attaching the plurality of fixing bars so that the deviation amount from the reference position of the attachment position of the plurality of fixing bars is equal to or less than a predetermined allowable deviation amount. It is possible to easily attach a plurality of anchor bars so that the bending moment generated in step 1 is equal to or less than the allowable bending moment of the pile head joint in consideration of the anchor bar mounting interval. As a result, the pile head joint can be easily constructed.

(9) The design drawing of the pile head joint according to at least one embodiment of the present invention,
Pile head joint design comprising a pile head, a plurality of anchoring bars arranged around the pile head, and a foundation concrete part constituted by concrete surrounding the pile head and the plurality of anchoring bars In the plan view of the pile head joint that is referred to by an operator who carries out the arrangement of the plurality of fixing muscles,
Each of the plurality of fixing muscles with respect to the pile head when the attachment positions of the plurality of fixing muscles when the plurality of fixing muscles are attached at equal intervals in the circumferential direction of the pile head The allowable deviation amount of the mounting position from the reference position is included.

  According to the above configuration (9), since the design drawing of the pile head joint includes the allowable deviation amount from the reference position of the plurality of fixing bars, the worker who performs the fixing bar installation work performs the installation work. It can proceed smoothly.

(10) The specification sheet of the fixing muscle for pile head according to at least one embodiment of the present invention is:
In the specification sheet for anchors for pile heads, which describes the specifications of multiple anchors placed around the pile head,
Each of the plurality of fixing muscles with respect to the pile head when the attachment positions of the plurality of fixing muscles when the plurality of fixing muscles are attached at equal intervals in the circumferential direction of the pile head The allowable deviation amount of the mounting position from the reference position is described.

  According to the above configuration (10), since the specifications of the anchors for the pile head include the allowable deviation from the reference position of the plurality of anchors, The design and construction of the head joint can be carried out smoothly.

(11) The fixing muscle attachment position confirmation device according to at least one embodiment of the present invention comprises:
It is a device for confirming the attachment position of the fixing muscle used in the construction method of the pile head joint of the above configuration (8),
A body that can be placed concentrically with the pile head on the pile head;
A mark provided on the main body and indicating the allowable deviation amount;
Is provided.

  According to the above configuration (11), the worker who performs the fixing bar attachment work visually recognizes the mark so that the deviation amount from the reference position of the fixing stripe attachment position is equal to or less than the allowable deviation amount. The fixing muscle can be attached smoothly.

According to at least one embodiment of the present invention, a pile in which the generated bending moment of the pile head is taken into account the mounting interval of the fixing bars even if the spacing of the fixing bars is not uniform in the circumferential direction of the pile head Provided is a method for designing a pile head joint that can be made equal to or less than an allowable bending moment of the head joint.
In addition, according to at least one embodiment of the present invention, even if the spacing between the fixing bars is not uniform in the circumferential direction of the pile head, the generated bending moment of the pile head is taken into account the fixing spacing of the fixing bars. Provided is a method for constructing a pile head joint that can be less than or equal to the allowable bending moment of the pile head joint.
Further, according to at least one embodiment of the present invention, even if the spacing between the fixing bars is not uniform in the circumferential direction of the pile head, the generated bending moment of the pile head is taken into account with the fixing bar mounting interval. A design drawing of the pile head joint that can be made below the allowable bending moment of the pile head joint is provided.
Further, according to at least one embodiment of the present invention, even if the spacing between the fixing bars is not uniform in the circumferential direction of the pile head, the generated bending moment of the pile head is taken into account with the fixing bar mounting interval. A specification of anchorage for pile head that can be made below the allowable bending moment of the pile head joint is provided.
According to at least one embodiment of the present invention, the generated bending moment of the pile head takes into account the installation interval of the fixing bars even if the spacing of the fixing bars is not uniform in the circumferential direction of the pile head. There is provided an apparatus for confirming the attachment position of a fixing head for a pile head, which can easily attach the fixing muscle so as to be equal to or less than an allowable bending moment of a pile head joint.

It is a figure which shows schematic structure of a structure. It is a figure for demonstrating a pile head junction part. It is a figure which shows schematically the pile head in FIG. 2, a joining member, a fixing muscle, and a fixing body, a left half is a side view, and a right half is sectional drawing. It is an upper surface figure which shows an example of the design drawing of a pile head junction part, and shows a pile head and a joining member roughly. It is a figure which shows a joining member schematically, (a) is a front view, (b) is a side view, (c) is a top view, (d) is a bottom view. It is a side view which shows a fixed muscle schematically. It is sectional drawing which shows a pile head part, a joining member, and a part of fixing muscle roughly. It is a top view which shows a part of pile head part, and a joining member schematically. It is a flowchart which shows roughly the procedure of the design method of the pile head junction part which concerns on one Embodiment of this invention. It is a figure for demonstrating the resistance mechanism model for calculating an allowable bending moment. It is a figure for demonstrating the reason which can consider the tensile yield strength of the axial part of a fixing muscle in the state B. FIG. It is a figure for demonstrating the proof stress increase of the foundation concrete part by the bearing effect in a pile head junction part. It is a figure for demonstrating the proof stress increase of the foundation concrete part by the bearing effect in the eccentric compression state in a pile head junction part. It is a figure which shows the case where the attachment space | interval of the fixing reinforcement in some embodiments is non-uniform | heterogenous. It is a figure which shows the detail of the symbol in the formula of [Equation 1]. It is a figure which shows the NM curve when the attachment space | interval of a fixing bar | burr is non-uniform | heterogenous as allowable bending moment data with the NM curve when the attachment space | interval of a fixing | fixed line | wire is equal intervals. It is a figure for demonstrating the attachment conditions of the several fixed reinforcement in the specification determination process in some embodiment. It is a table | surface which shows the example of the specification of the fixing streak determined at the specification determination process. It is a flowchart for demonstrating the schematic procedure of an allowable bending moment data preparation process. It is a flowchart for demonstrating the schematic procedure of the design method of the pile head junction part which concerns on other embodiment. It is a figure for demonstrating the allowable bending moment data prepared with the design method of a pile head junction part. It is a flowchart for demonstrating the schematic procedure of the construction method of the pile head junction part which concerns on one Embodiment of this invention. It is a figure which shows roughly the specification of the fixed reinforcement for pile heads concerning one Embodiment of this invention. It is a part of table | surface (pile diameter 400mm-900mm) for demonstrating the design method of the pile head junction part which concerns on other one Embodiment of this invention. It is a part of table | surface (pile diameter 1000mm-1200mm) for demonstrating the design method of the pile head junction part which concerns on other one Embodiment of this invention. It is a top view which shows roughly the attachment position confirmation apparatus of the fixing reinforcement for pile heads which concerns on one Embodiment of this invention.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  Hereinafter, although the design method and manufacturing method of the pile head junction part which concern on embodiment of this invention are demonstrated, an example of the pile head junction part of a design object is demonstrated first as the premise.

[Configuration of pile head joint]
FIG. 1 is a diagram illustrating a schematic configuration of the structure 1. The structure 1 includes a plurality of piles 2, a pile cap 4a joined to each of the pile heads of the plurality of piles 2, a beam 5 connecting the pile caps 4a, and the pile 2 via the pile cap 4a. With a supported superstructure 6. The pile 2, the pile cap 4 a and the beam 5 constitute a pile foundation 8 for supporting the upper structure 6.
The pile foundation 8 may have a footing instead of the pile cap 4a. Hereinafter, the pile cap 4a and the footing are also referred to as a foundation concrete portion 4.

  FIG. 2 is a diagram for explaining the pile head joint 10. FIG. 3 is a diagram schematically showing a pile head, a joining member, a fixing muscle, and a fixing body in FIG. 2, in which the left half is a side view and the right half is a cross-sectional view. FIG. 4 is a top view schematically showing a pile head and a joining member. 5A and 5B are diagrams schematically showing a joining member, in which FIG. 5A is a front view, FIG. 5B is a side view, FIG. 5C is a top view, and FIG. 5D is a bottom view. FIG. 6 is a side view schematically showing the fixing muscle. FIG. 7 is a cross-sectional view schematically showing a part of the pile head, the joining member, and the fixing muscle. FIG. 8 is a top view schematically showing a part of a pile head and a joining member.

As shown in FIGS. 1 to 8, the pile head joint portion 10 includes an upper end portion (pile head portion) 12 of the pile 2, a plurality of joint members 14, a plurality of fixing bars 16, and a foundation concrete portion 4. It has.
The pile 2 may be a cast-in-place pile or a ready-made pile. In the present embodiment, the fixing bar 16 is fixed to the pile head 12 via the joining member 14, but the joining member 14 is omitted and the fixing bar 16 is directly fixed to the pile head 12 by welding or the like. May be.

In consideration of welding the joining member 14 or the fixing bar 16 to the outer peripheral surface of the pile head 12, in the case of a cast-in-place pile, the pile 2 is a steel pipe concrete pile. In the case of a ready-made pile, the pile 2 is a steel pipe pile (SPP pile) or a concrete pile with an outer shell steel pipe (SC pile), or a concrete having a steel reinforcing band attached to the upper end. Pile, for example, reinforced concrete pile (RC pile), prestressed concrete pile (PC pile, PRC pile), or high strength prestressed concrete pile (PHC pile).
In addition, the fixing method of the joining member 14 or the fixing bar | burr 16 is not limited to welding, It is also possible to use another type as the pile 2.

  In this embodiment, the pile 2 is an SC pile and covers a cylindrical concrete portion 17 made of concrete, a metal end plate 18 covering both ends of the concrete portion 17, and an outer peripheral surface of the concrete portion 17. And an outer shell steel pipe 19. The end plate 18 has an annular shape and is welded to the outer shell steel pipe 19.

The plurality of joining members (joint couplers) 14 are made of metal, and are fixed to the outer peripheral surface of the pile head 12 by welding at intervals in the circumferential direction of the pile head 12.
The plurality of fixing muscles 16 are made of metal, and are respectively attached to the pile heads 12 via the joining members 14.
The foundation concrete portion 4 is made of concrete and surrounds the pile head 12, the plurality of joining members 14, and the plurality of fixing muscles 16. The concrete of the foundation concrete portion 4 has, for example, a design standard strength Fc of 24 N / mm ² .
Although not shown in the drawings, as the reinforcing bars other than the fixing bars 16, split reinforcement bars, the main bars of the beam 5 extending in the horizontal direction, the main bars of the column of the upper structure 6 extending in the vertical direction, and the like are arranged in the foundation concrete portion 4. It may be.

In the present embodiment, the fixing muscle 16 includes a shaft portion 20 and a screw portion 21 that is connected to one end side of the shaft portion 20 and has a smaller cross-sectional area than the shaft portion 20. The fixing muscle 16 may have screw portions 21 on both sides of the shaft portion 20. In this case, a nut as a fixing body 22 may be screwed to the screw portion 21 on the upper end side of the fixing bar 16, and a deformed reinforcing bar or unbonded (round steel) can be used as the fixing bar 16.
For example, a deformed reinforcing bar as shown in FIG. 6 can be used as the fixing bar 16, but the shape of the fixing bar 16 is not limited to that shown in FIG.

  The bonding member 14 includes a lower protrusion 23 and an upper protrusion 24. The lower protrusion 23 and the upper protrusion 24 are fixed to the outer peripheral surface of the pile head 12 by welding, and protrude laterally from the outer peripheral surface of the pile head 12. The upper protrusion 24 is disposed above the lower protrusion 23 in the axial direction of the pile head 12. For example, the joining member 14 is welded to the outer peripheral surface of the pile head 12 so that the position of the upper surface of the upper protrusion 24 matches the position of the upper end surface of the pile head 12 in the axial direction of the pile head 12. Is done.

  The screw portion 21 of the fixing muscle 16 is coupled to the lower protrusion 23. For example, as shown in FIG. 5, a screw hole 26 is formed in the lower protrusion 23, and the screw part 21 is screwed into the screw hole 26. Or although not shown in figure, a through-hole is formed in the lower side projection part 23, and a nut is welded on the lower side of the lower side projection part 23 coaxially with a through-hole. In this case, the nut can be regarded as a part of the lower protrusion 23, and the screw 21 can be regarded as being screwed into the lower protrusion 23 by screwing the screw 21 into the nut. it can.

The shaft portion 20 of the fixing muscle 16 extends between the lower projection portion 23 and the upper projection portion 24 in the axial direction of the pile head portion 12 and projects upward from the end surfaces of the upper projection portion 24 and the pile head portion 12. It is extended.
Therefore, the upper protrusion 24 has a shape that allows the fixing muscle 16 to pass therethrough. On the other hand, the upper protruding portion 24 includes the portion of the foundation concrete portion 4 attached to the portion of the shaft portion 20 of the fixing muscle 16 extending between the lower protruding portion 23 and the upper protruding portion 24 and the axis of the pile head portion 12. It is configured to engage in a direction.
For example, as shown in FIG. 5, the upper protruding portion 24 has a fork portion 29 in which a notch 28 that allows the fixing muscle 16 to pass is formed, and the fork portion 29 is concrete attached to the shaft portion 20. It is comprised so that a part of part 4 and the pile head part 12 may be engaged in the axial direction.

Preferably, the joining member 14 further includes a connecting portion 30 formed integrally with the lower protrusion 23 and the upper protrusion 24, two reinforcing beam portions 32, and two reinforcing rib portions 34.
The connecting portion 30 has a plate shape extending in the axial direction and the circumferential direction of the pile head portion 12, and connects the lower protruding portion 23 and the upper protruding portion 24 to each other. The connection part 30 has the curved surface 35 which can be arrange | positioned along the outer peripheral surface of the pile head 12 on the pile head 12 side.
The reinforcing beam portion 32 extends in the axial direction of the pile head portion 12 and has a prismatic shape. The reinforcing beam portion 32 is integrally formed on both sides of the connecting portion 30 in the circumferential direction of the pile head portion 12. The reinforcing beam portion 32 extends between the lower protrusion 23 and the upper protrusion 24.
The reinforcing rib portion 34 is integrally formed at a corner formed between the reinforcing beam portion 32 and the lower protrusion 23.

Preferably, as shown in FIG. 8, both sides of the connecting portion 30 are welded to the outer peripheral surface of the pile head 12 in the circumferential direction of the pile head 12. Therefore, a groove surface 36 inclined with respect to the outer peripheral surface of the pile head 12 is provided on both sides of the connecting portion 30 in the circumferential direction of the pile head 12, and the outer periphery of the groove surface 36 and the pile head 12 is provided. A weld bead 38 is formed between the surfaces. Preferably, the groove surface 36 and the weld bead 38 extend from the lower protrusion 23 to the upper protrusion 24 in the axial direction of the pile head 12.
In addition, the shape of the joining member 14 is not limited to what was mentioned above, For example, the joining member described in Unexamined-Japanese-Patent No. 2015-34458 can be used.

[Pile head joint design method]
FIG. 9 is a flowchart schematically showing a procedure of a method for designing a pile head joint according to an embodiment of the present invention. FIG. 10 is a diagram for explaining a resistance mechanism model for calculating an allowable bending moment.
As shown in FIG. 9, the pile head joint design method includes an allowable bending moment data preparation step S1, a generated bending moment calculation step S2, and a specification determination step S3.

  In the allowable bending moment data preparation step S1, the specifications of the pile head joint 10, that is, the specifications of the pile head 12, the joint member 14, the anchor reinforcement 16, and the foundation concrete part 4, are assumed, and the allowable bending of the pile head joint 10 is assumed. Allowable bending moment data corresponding to the moment (short-term allowable bending moment) sMa is prepared. The allowable bending moment data may be the allowable bending moment sMa that is directly calculated based on the specifications of the pile head joint 10, or may be a value that allows for a predetermined remaining force in the allowable bending moment.

The specification of the pile head 12 is the specification of the pile 2 and includes a pile diameter, a pile type, a wall thickness, a plate thickness, a material, and the like. The specifications of the joining member 14 are the shape, size, material, and the like of the joining member 14. The specifications of the fixing muscle 16 are the shape, size, number, arrangement, material, and the like of the fixing muscle 16. The specifications of the foundation concrete part 4 are the shape, dimensions, strength, etc. of the foundation concrete part 4. Further, the specifications of the foundation concrete portion 4 include the relative arrangement relationship between the pile head 12 and the foundation concrete portion 4, that is, the embedded length hp of the pile head 12 and the edge h '.
In addition, when not using the joining member 14, it is not necessary to consider the specification of the joining member 14. FIG.

In generating the bending moment calculation step S2, when the horizontal force is applied to the pile head joint 10, to calculate the generation bending moment M ₀ generated pile head 12.

In specification determination step S3, based on the allowable bending moment data and generate the bending moment M _0, propriety of specifications of pile head joint 10 that is assumed by the permissible bending moment data preparing step S1 is determined. For example, in specification determination step S3, by comparing the generated bending moment M ₀ of the allowable bending moment data and pile head 12, is smaller than generating the bending moment M ₀ is allowable bending moment data is appropriate is assumed Specifications The assumed specification is adopted.

  For example, in the allowable bending moment data preparation step S1, the allowable bending moment sMa is calculated based on the resistance mechanism model shown in FIG. When a shearing force Q acts on the pile head joint 10 and a bending moment M is generated, it is considered that the following mechanisms I, II, and III are appropriately combined to resist the bending moment M.

As shown in FIG. 10A, the mechanism I is a resistance as a virtual RC cross section in which the fixing muscle 16 is regarded as the main muscle, and the compression force C acting on the fixing muscle 16 and the pile head 12 and the fixing muscle. 16 is a resistance against a tensile force T acting on the member 16. Hereinafter, the component of the allowable bending moment sMa by the mechanism I is also referred to as a first allowable bending moment component sMa1.
The mechanism II is resistance to the compressive force C acting on the outer peripheral surface of the pile head portion 12 from the foundation concrete portion 4 as shown in FIG. Hereinafter, the component of the allowable bending moment sMa by the mechanism II is also referred to as a second allowable bending moment component sMa2.
As shown in FIG. 10C, the mechanism III is a resistance against the compressive force C acting on the unevenness of the joining member 14 from the basic concrete portion 4. Hereinafter, the component of the allowable bending moment sMa by the mechanism III is also referred to as a third allowable bending moment component sMa3.

And in the allowable bending moment data preparation step S1 of the present embodiment, the upper portion 40 of the foundation concrete portion 4 surrounding the portion of the shaft portion 20 of the fixing bar 16 protruding upward from the end face of the pile head portion 12, and the lower protrusion It is assumed that a crack 44 is generated between the lower portion 42 of the foundation concrete portion 4 surrounding the portion of the shaft portion 20 of the fixing muscle extending between the portion 23 and the upper protrusion portion 24 (FIG. 10A). )reference). The crack 44 typically extends downward from the upper protrusion 24 obliquely by 45 degrees. For this reason, the crack 44 is also referred to as an oblique crack 44.
In the following description, a state where no crack 44 is generated is also referred to as “state A”, and a state where the crack 44 is generated is also referred to as “state B”. In the present embodiment, it is assumed that the state is B.

In the state B, due to the presence of the crack 44, the mechanism III in the resistance mechanism model cannot be expected, and the resistance based on the mechanism III needs to be ignored.
On the other hand, regardless of the presence or absence of the crack 44, it is necessary to consider the tensile yield strength of the anchoring muscle 16 as the mechanism I. However, when the crack 44 exists, the tensile yield strength of the anchoring muscle 16 is The tensile yield strength of the shaft portion 20 of the fixing muscle 16 can be considered. The cross-sectional area of the shaft portion 20 is larger than the cross-sectional area of the screw portion 21, and the tensile yield strength of the shaft portion 20 is larger than the tensile yield strength of the screw portion 21. For this reason, the fact that the tensile yield strength of the shaft portion 20 of the anchoring muscle 16 can be taken into account works advantageously in calculating the allowable bending moment sMa.

  FIG. 11 is a diagram for explaining the reason why the tensile yield strength Tby of the shaft portion 20 of the fixing muscle 16 can be considered in the state B. When the crack 44 is generated, since the lower portion 42 of the foundation concrete portion 4 is attached to the fixing reinforcement 16 below the crack 44, the generation of the resistance force Fsb due to the attachment can be expected. In general, the sum (Fsb + Tsy) of the resistance force Fsb and the tensile yield strength Tsy of the screw portion 21 is designed to be equal to or greater than the tensile yield strength Tby of the shaft portion 20, so that the tensile yield strength of the shaft portion 20 is increased. Up to Tby, the fixing muscle 16 can withstand.

For this reason, in the allowable bending moment data preparation step S1 of the present embodiment, when calculating the resistance of the fixing reinforcement 16 protruding upward from the end of the pile head 12 and the foundation concrete portion 4 surrounding the fixing reinforcement 16, While considering the tensile yield strength Tby of the shaft portion 20 of the fixing bar 16, the allowable bending moment sMa is calculated ignoring the resistance acting on the foundation concrete portion 4 from the joining member 14. That is, the first allowable bending moment component sMa1 is calculated as the allowable bending moment sMa.
The calculation of the allowable bending moment sMa in consideration of the tensile yield strength Tby is, specifically, the calculation of the allowable bending moment sMa using a function that directly or indirectly includes the tensile yield strength Tby as a variable. Means that.

  According to the allowable bending moment data preparation step S1 using the resistance mechanism model described above, when it is assumed that the crack 44 is generated in the foundation concrete portion 4, that is, in the state B, the tensile yield of the shaft portion 20 of the fixing bar 16 is obtained. While considering the strength Tby, the allowable bending moment sMa can be accurately calculated by calculating the allowable bending moment sMa while ignoring the resistance acting on the foundation concrete portion 4 from the joining member 14.

  In the above-described allowable bending moment data preparation step S1, the resistance based on the mechanism II, that is, the side resistance of the pile head 12 may or may not be considered. When considering the resistance based on the mechanism II, the sum (sMa1 + sMa2) of the first allowable bending moment component sMa1 and the second allowable bending moment component sMa2 may be calculated as the allowable bending moment sMa. Thus, if the resistance based on the mechanism II is taken into consideration, the allowable bending moment sMa is increased, and the specifications of the pile head 12, the joining member 14, the fixing reinforcement 16, and the foundation concrete portion 4 can be suppressed. On the other hand, if the resistance based on the mechanism II is not taken into consideration, the allowable bending moment sMa becomes small, and a safety factor can be expected.

Hereinafter, the mechanisms I to III shown in FIGS. 10A to 10C will be described in detail.
[Mechanism I]
The resistance based on the mechanism I is a resistance due to the compressive force C generated in the pile head 12 and the tensile force T of the fixing muscle 16. Here, as shown in FIG. 12, the pile head joint part 10 compresses the concrete of the foundation concrete part 4 (pile cap 4a) larger than the pile cross-sectional area Ac. For this reason, the compressive proof stress fc of the concrete which the pile head junction part 10 contact | connects rises by the local bearing effect. Pile cap cross-sectional area (support area) A ₀ and Kuidan area (Bearing area) Ac ratio is 5 times or more, Bearing effect of more than twice the expected pure compression. Note that due to the bearing effect, the compressive yield strength fc of the concrete is (A ₀ / Ac) ^0.5 times.

And as shown in FIG. 13, when the eccentric compression state by bending is taken into consideration, the bearing area Ac ′ is smaller than the pile cross-sectional area Ac, and the bearing effect is further increased.
In calculating the resistance based on the mechanism I, that is, the first allowable bending moment component sMa1, an increase in yield strength due to the bearing effect is taken into account in the present embodiment by enlarging the virtual RC sectional diameter D.
As in the present embodiment, when the allowable bending moment sMa of the pile head joint 10 is calculated, the fixing muscle 16 resists the tensile force T, and a cylindrical body having a virtual RC cross section is generated in the foundation concrete portion 4. It is common to assume that the compressive force C is borne.

  In the case of the pile head joint method using the main reinforcement method as in this embodiment, it is described in the Architectural Institute of Japan “Guideline for Structural Design of Architectural Buildings (1988)” or Road Association “Pile Foundation Design Handbook 2006 Revised Edition”. A method of performing cross-sectional inspection of a pile head joint as a virtual RC cross section having a diameter D obtained by adding 200 mm to the pile diameter is common. Recently, in the Road Association “Road Bridge Specification / Explanation IV Substructure” revised in March 2012, the diameter D of the virtual RC cross section is set to 0.25Dp + 100mm to the pile diameter Dp. A method of checking as a diameter with 400 mm) added is shown. The Japan Road Association is reviewing and revising the diameter D of the virtual RC cross section. Therefore, also when calculating the allowable bending moment sMa in the present embodiment, it is possible to employ a cross-sectional verification method for the pile head joint 10 assuming a virtual RC cross-section.

Therefore, a length (hereinafter also referred to as an effective adhesion length) in which the foundation concrete portion 4 adheres to the shaft portion 20 of the fixing bar 16 between the lower projection portion 23 and the upper end of the upper projection portion 24 is Le. In this case, a value obtained by adding 2Le to the pile diameter Dp is set as the maximum value of the diameter D of the virtual RC cross section. That is, the fixing bars 16 resist the tensile force, and the compressive force generated in the foundation concrete portion 4 is assumed to be borne by the cylindrical body having the virtual RC cross-sectional diameter D (where D = Dp + 2Le).

Preferably, between the diameter D of the virtual RC cross section and the pile diameter Dp, the following formula:
Dp + Le ≦ D ≦ Dp + 2Le
The diameter D is selected so that the relationship indicated by
More preferably, between the diameter D of the virtual RC cross section and the pile diameter Dp, the following formula:
Dp + 1.5Le ≦ D ≦ Dp + 2Le
The diameter D is selected so that the relationship indicated by
For example, the effective adhesion length Le is 140 mm or more and 200 mm or less.

  By selecting the diameter D of the virtual RC cross section in this way, the size of the virtual RC cross section diameter D can be set larger than the conventional one. As the virtual RC sectional diameter D is larger, the stress acting on the foundation concrete portion 4 and the pile head portion 12 can be reduced, and the allowable bending moment sMa can be calculated larger. As a result, according to the above configuration, the pile head joint 10 having a sufficiently large allowable bending moment sMa can be realized with low-cost specifications.

  Then, the first allowable bending moment component sMa1 by the mechanism I may be appropriately calculated by a known procedure. For example, there is a method of calculating with reference to the Japan Architectural Institute “Reinforced Concrete Structure Calculation Standards / Description (2010)” and a method of calculating using a bending analysis assuming that the plane of the cross section is maintained.

FIG. 14 shows a case where the attachment intervals of the fixing bars 16 are not uniform in some embodiments. In the state B where the crack 44 is generated, the nominal cross-sectional area of the shaft portion 20 of the fixing bar 16 is used as the nominal cross-sectional area a _b of one fixing bar. Note that the symbols in FIG. 14 represent the following, respectively.
D: Diameter of virtual RC cross section (mm)
D _b : Arrangement diameter of fixing muscle (mm)
d _c : distance from the compression edge to the center of gravity of the compression-side fixing muscle (mm)
d _t : Distance from the tension edge to the center of gravity of the tension-side anchoring muscle (mm)
R: Radius of virtual RC cross section (mm)
R _b : Arrangement radius of fixing muscle (mm)
X ₀ : Distance from the centroid of the virtual RC section to the neutral axis (mm)
θ: angle (rad) defining the neutral axis position in a circular cross section
θ _j : Arrangement angle (rad) of fixing muscle position

[Mechanism II]
The second allowable bending moment component sMa2 by the mechanism II is the side resistance (pile side resistance) of the pile head 12 and is due to the bearing resistance of the foundation concrete portion 4, and is expressed by the following [Equation 1]. Can be calculated. As the bearing pressure strength σ _c of the mechanism II, 2/3 · F _c which is an allowable compressive stress degree of the RC structure can be used.
However, with respect to bearing capacity sigma _c, it may be taken into consideration an increase in compressive strength due to restraint effect of the pile cap 4a which pile 2 is embedded.
Further, in the allowable bending moment data preparation step S1, the second allowable bending moment component sMa2 may or may not be considered.
FIG. 15 shows details of symbols in the formula.

[Mechanism III]
Third allowable bending moment component sMa3 by mechanism III are the same calculation method as for obtaining the first allowable bending moment component sMa1 by Scheme I substituting the allowable tensile strength of the fixing muscle 16 in compressive strength C _c due to unevenness of the bonding member 14 (RC allows local plasticization of concrete during short-term tolerance). It is considered that the strength of the compression reaction force of the unevenness of the joining member 14 is determined by the bearing pressure failure of the concrete (in this case, the oblique cracks 44 from the joining member 14 do not occur. The yield strain of the fixing bar 16 is the concrete compressive yield. Greater than strain).
However, the third allowable bending moment component sMa3 is ignored in the allowable bending moment data preparation step S1 when it is assumed that the oblique crack 44 is generated in the pile head joint 10.
Also, if the expected resistance by mechanisms III, the joining member 14 is designed so as not to yield the compression force C _c.
When the joining member 14 is omitted and the fixing bar 16 is directly fixed to the pile head 12 by welding or the like, it is not necessary to consider the mechanism III.

On the other hand, in the generation bending moment calculation step S2, the generated bending moment M ₀ generated pile head 12 when the horizontal force H acts, for example, be determined by a formula shown in the following expression (2).

  Here, in this embodiment, as shown in FIGS. 4 and 14, in the allowable bending moment data preparation step S <b> 1, the mounting intervals of the plurality of fixing bars 16 in the circumferential direction of the pile head 12 are not uniform. Prepare the permissible bending moment data.

  FIG. 16 shows an NM curve when the attachment intervals of the fixing bars 16 are not uniform as allowable bending moment data, together with an NM curve when the attachment intervals of the fixing bars 16 are equal. When the fixing spacing 16 is not uniform, anisotropy occurs in the allowable bending moment sMa (bending strength), so that the bending strength is large (strong axis direction) and the bending strength is small (weak axis direction). Appears. In the example shown in FIG. 16, when the permissible bending moment sMa in the weak axis direction when the fixing interval of the fixing bars 16 is non-uniform, when the axial force N is 0 kN, the fixing interval of the fixing bars 16 is uniform. The allowable bending moment sMa is reduced to 80%.

Although not shown in FIG. 2, in the pile head joint portion 10, overstrikes are generated by the main bars of the beams 5 and the main bars of the columns of the upper structure 6, and the fixing bars 16 may not be arranged at equal intervals. Assuming such a situation, the designer of the pile head joint portion 10 has the generated bending moment M ₀ of the pile head 12 that is equal to the fixing muscle 16 even when the attachment interval of the fixing muscles 16 becomes uneven. The pile head joint 10 may be designed so that the allowable bending moment sMa or less, that is, the allowable bending moment data or less is taken into consideration.

According to the above configuration, the designer of the pile head joint 10 allows the allowable bending moment corresponding to the allowable bending moment sMa when the mounting intervals of the plurality of fixing bars 16 in the circumferential direction of the pile head 12 are uneven. By preparing the data, the bending moment M ₀ generated in the pile head 12 can be reduced in the pile head joint 10 in consideration of the attachment interval of the fixing bars 16 even if the fixing bars 16 are not evenly spaced. The specification of the pile head joint 10, that is, the attachment interval of the fixing bars 16 can be determined so as to be equal to or less than the allowable bending moment sMa.

And FIG. 17 is a figure for demonstrating the attachment conditions of the several fixed reinforcement 16 in the specification determination process S3 in this embodiment. FIG. 18 is a table showing an example of the specification of the fixing streak 16 determined in the specification determination step S3.
In the present embodiment, as shown in FIGS. 17 and 18, in the specification determination step S <b> 3, as the mounting condition for the plurality of fixing bars 16, the plurality of fixing bars 16 are equally spaced in the circumferential direction of the pile head 12. When the attachment position at the time of attachment is the reference position P0, an allowable deviation amount ΔPj from the reference position P0 of the attachment positions of the plurality of fixing stripes 16 is determined. Here, deviation amount of the fixing muscle 16 is represented by a straight line distance connecting the actual mounting position and the reference position P0 of the fixing muscle 16, the allowable deviation amount ΔPj the bending allowable occurrence bending moment M ₀ Moment This is the maximum value of the displacement amount of the fixing streaks 16 that is equal to or less than the data, and is a size common to all the fixing streaks 16. Each fixing line 16 may be displaced in any direction in the circumferential direction of the pile head 12 from the reference position P0 as long as it is within the range of the allowable deviation amount ΔPj. In the present embodiment, a linear distance connecting the reference position P0 of each fixing bar 16 and the allowable farthest mounting position is used as the allowable deviation amount ΔPj, but the axis of the pile head 12 is centered. The arc angle (center angle) Δθ connecting the reference position P0 of each fixing muscle 16 and the allowable farthest mounting position may be used.
Note that the attachment position of the fixing muscle 16 is a position where the fixing muscle 16 is attached on the outer peripheral surface of the pile head 12, but the fixing muscle 16 is connected to the pile head 12 via a member such as the joining member 14. When arranged and fixed around, the line connecting the center of the pile head 12 and the center of the fixing muscle 16 is assumed to be a position intersecting the outer peripheral surface of the pile head 12. By defining in this way, when the displacement amount of the fixing muscle 16 is expressed by a linear distance, the fixing muscle 16 is not directly attached to the pile head 12 by using a member such as the joining member 14. However, it is possible to prevent the display position of the displacement amount of the fixing muscle 16 from being changed because the attachment position of the fixing muscle 16 to the pile head 12 does not change.

According to the above configuration, the allowable deviation amount ΔPj from the reference position P0, which is an equidistant mounting position, is determined as the mounting condition of the fixing muscle 16, and when the fixing muscle 16 is arranged, in the specification determining step S3. If the determined mounting condition of the fixing bar 16 is observed, the bending moment M ₀ generated in the pile head 12 is surely equal to or less than the allowable bending moment sMa of the pile head joint 10 taking the mounting interval of the fixing bar 16 into account. can do.
As is apparent from FIG. 18, the allowable displacement amount ΔPj changes depending on the pile diameter Dp and the total number of attachments of the fixing bars 16.

In some embodiments, in the specification determination step S3, the allowable deviation amount ΔPj is determined in consideration of the deviation direction of each of the fixing stripes 16 as an attachment condition for the plurality of fixing stripes 16.
When the common allowable deviation amount ΔPj is determined for the attachment positions of the plurality of fixing bars 16, the allowable bending moment sMa changes depending on the combination of the deviation directions from the reference position P0 of the fixing bars 16.
In this regard, according to the above-described configuration, the allowable deviation ΔPj is determined in consideration of the deviation direction of each fixing bar 16 so that the generated bending moment M ₀ is equal to or less than the allowable bending moment data. The amount ΔPj can be determined accurately.
When considering the displacement direction of each fixing muscle 16, the allowable bending moment sMa may be calculated for each combination of the displacement directions of each fixing muscle 16, and the smallest allowable bending moment sMa may be adopted.

In some embodiments, in the specification determination step S3, the allowable bending moment sMa of the pile head joint 10 when the mounting intervals of the plurality of fixing bars 16 are non-uniform under a predetermined axial force, for example, 0 kN, The specification of the pile head joint portion 10 is determined so that it becomes a predetermined ratio or more in comparison with the allowable bending moment sMa when the attachment intervals of the plurality of fixing bars 16 are equal intervals.
In addition, the pile head in the case where the attachment space | interval of the several fixing reinforcement 16 with respect to the allowable bending moment sMa of the pile head joint part when the attachment space | interval of the several fixation reinforcement 16 is equal intervals in axial force 0kN is nonuniform. The ratio of the allowable bending moment sMa of the joint 10 is also referred to as an axial force 0 kNM reduction rate. Further, the allowable bending moment sMa used for calculating the reduction rate of the axial force 0 kNM is the second allowable bending moment component sMa2 (side resistance of the pile head 12) by the mechanism II in both the non-uniform arrangement and the equidistant arrangement. The third allowable bending moment component sMa3 by the mechanism III is not taken into consideration.

According to the above configuration, in the specification determining step S3, the allowable bending moment sMa of the pile head joint 10 when the mounting intervals of the plurality of fixing bars 16 are non-uniform, the mounting intervals of the plurality of fixing bars 16 are equal. Since the specification of the pile head joint 10 is determined so as to be a predetermined ratio or more compared to the allowable bending moment sMa in a certain case, the allowable bending moment sMa of the pile head joint 10 taking into account the mounting interval of the fixing bars 16 is determined. Can be prevented from becoming excessively small.
The ratio is not particularly limited, and is set to, for example, 70% to 95%, preferably 80% to 90%. The higher the ratio, the larger the allowable bending moment when considering the attachment interval of the fixing bars 16. On the other hand, the mounting conditions of the fixing bars 16 that must be observed during construction become strict.

In some embodiments, the minimum mounting interval Pjmin of the anchoring bars 16 is set at an allowable bending moment sMa of the pile head joint 10 taking into account the mounting distance of the anchoring bars 16 under a predetermined axial force, for example, 0 kN. It is set so as not to fall below a preset ratio as compared with the allowable bending moment sMa when the mounting intervals of the plurality of fixing bars 16 are equal. For this reason, the minimum attachment interval Pjmin of the fixing bars 16 may be appropriately changed according to the construction method and construction conditions (welding conditions, etc.).
For example, when the allowable bending moment taking into account the attachment interval of the fixing bars 16 is 80% or more of the allowable bending moment when the attachment intervals of the fixing bars 16 are equal, the minimum attachment interval Pjmin is 132 mm. Is set.
Note that the minimum mounting interval Pjmin can also be expressed by an angle as long as the pile diameter is clear, as in the case of the allowable deviation amount ΔPj.

  FIG. 19 is a flowchart for explaining a schematic procedure of the allowable bending moment data preparation step S1. In some embodiments, as shown in FIG. 19, the allowable bending moment data preparation step S1 stores the mounting intervals of the plurality of fixing bars 16 and the allowable bending moment sMa of the pile head joint 10 in association with each other. A database access step S10 for accessing the database is included. In the allowable bending moment data preparation step S1, allowable bending moment data is selected from the database.

According to the configuration described above, by preparing a database in which the mounting intervals of the plurality of fixing bars 16 and the allowable bending moment sMa of the pile head joint 10 are stored in advance, the mounting intervals of the plurality of fixing bars 16 are prepared. Even if this is not uniform, the allowable bending moment data of the pile head joint 10 can be easily prepared.
That is, the allowable bending moment data may be calculated each time the pile head joint 10 is designed, or may be acquired from a database prepared in advance.
The database is stored in, for example, a server and can be accessed through the Internet.

FIG. 20 is a flowchart for explaining a schematic procedure of a method for designing a pile head joint according to another embodiment. FIG. 21 is a diagram for explaining allowable bending moment data prepared by the method for designing the pile head joint.
In some embodiments, as illustrated in FIG. 20, the method for designing a pile head joint further includes a ratio preparation step S <b> 4.
In the ratio preparation step S4, when the mounting intervals of the plurality of fixing bars 16 with respect to the permissible bending moment sMa under the predetermined axial force N are equal, the mounting intervals of the plurality of fixing bars 16 are not uniform. A ratio of the allowable bending moment sMa is prepared. The axial force N acts on the pile head 12 in the axial direction, and the predetermined axial force N is, for example, 0 kN.

  Then, in the allowable bending moment data preparation step S1, the allowable bending moment data is obtained by multiplying the allowable bending moment sMa when the mounting intervals of the plurality of fixing bars 16 are equal to each other by the ratio prepared in the ratio preparing step S4. prepare. In FIG. 21, the NM curve as the allowable bending moment data is obtained by multiplying the NM curve when the interval between the fixing stripes 16 is equal.

According to the above configuration, the plurality of fixing bars 16 is obtained by multiplying the ratio prepared in advance by the allowable bending moment sMa of the pile head joint 10 when the mounting intervals of the plurality of fixing bars 16 are equal. The permissible bending moment data can be easily prepared when the mounting interval is uneven. The NM curve obtained in this way is smaller than the NM curve directly calculated based on the attachment interval of the fixing bars 16, and a safety factor can be expected.
For example, the ratio is stored in the server in association with the mounting intervals of the plurality of fixing bars 16 and can be accessed through the Internet.

[Pile head joint construction method]
Hereinafter, the construction method of the pile head junction part which concerns on one Embodiment of this invention is demonstrated.
FIG. 22 is a flowchart for explaining a schematic procedure of a method for constructing a pile head joint according to an embodiment of the present invention.
As illustrated in FIG. 2, the pile head joint construction method includes a pile head 12, a plurality of fixing muscles 16 arranged around the pile head 12, a pile head 12, and a plurality of fixing muscles 16. It is a construction method of the pile head joint part 10 provided with the foundation concrete part 4 comprised with the concrete which surrounds.

The construction method of the pile head joint includes a fixing bar attaching step S5 for attaching a plurality of fixing bars 16 at predetermined positions in the circumferential direction of the pile head 12, and a concrete placing step S6.
In the fixing bar attaching step S5, as shown in FIGS. 17 and 18, for each of the plurality of fixing bars 16, the deviation amount of the attachment position from the reference position P0 is equal to or less than a predetermined allowable deviation amount ΔPj. A plurality of fixing muscles 16 are attached to the pile head 12 so as to be. The expression of attaching the fixing muscle 16 to the pile head 12 is not only directly attaching the fixing muscle 16 to the pile head 12 but also around the pile head 12 via a member such as the joining member 14. It also includes disposing the fixing muscle 16 and fixing it.
In the concrete placing step S <b> 6, concrete is placed so as to surround the pile head 12 and the fixing reinforcement 16.

According to the above configuration, even when the attachment positions of the fixing streaks 16 are unevenly arranged at the site, the deviation amounts of the attachment positions from the reference position P0 are designated in advance for each of the plurality of fixing streaks 16. The pile head joint 10 in which the bending moment M ₀ generated in the pile head 12 takes into account the attachment interval of the anchor bars 16 by attaching the plurality of anchor bars 16 so as to be equal to or less than the allowable deviation ΔPj. The plurality of fixing muscles 16 can be easily attached so as to be equal to or less than the allowable bending moment sMa. As a result, the pile head joint 10 can be easily constructed.

[Design of pile head joint]
Hereinafter, a design drawing of a pile head joint according to an embodiment of the present invention will be described.
The plan view of the pile head joint includes a pile head 12, a plurality of fixing muscles 16 arranged around the pile head 12, and a foundation constituted by concrete surrounding the pile head 12 and the plurality of fixing bars 16. It is a design drawing of the pile head joint part 10 provided with the concrete part 4, Comprising: The operator who implements the attachment operation | work of the several fixing reinforcement 16 refers.
As illustrated in FIG. 4, the design diagram of the pile head joint according to the present embodiment includes the allowable deviation amount ΔPj of the plurality of fixing muscles 16 as information.

According to the above configuration, since the design drawing of the pile head joint includes the allowable deviation amount ΔPj from the reference position P0 of the plurality of fixing bars 16, the operator who performs the fixing work of the fixing bars 16 Can proceed smoothly.
In addition, the design drawing in this specification should just be referred to by the worker who performs the attachment work of the fixing bar 16, and includes a specification special note etc. in addition to the pile drawing. The medium of the design drawing is not limited to a document, and may be displayed on a display device such as a liquid crystal monitor.

In some embodiments, as illustrated in FIG. 4, the design of the pile head joint includes the minimum mounting interval Pjmin of the plurality of fixing bars 16 together with the allowable deviation amount ΔPj.
According to the above configuration, since the design drawing of the pile head joint portion further includes the minimum mounting interval Pjmin of the plurality of fixing bars 16, the operator who performs the fixing work of the fixing bars 16 further proceeds the mounting work more smoothly. be able to.

[Specification of anchorage for pile head]
Hereinafter, the specification of the fixing rod for pile head according to an embodiment of the present invention will be described.
FIG. 23 schematically shows a specification sheet for anchorage for a pile head according to one embodiment of the present invention. 23. As shown in FIG. 23, the specification of the fixing muscles for the pile head describes the specifications of the plurality of fixing muscles 16 arranged around the pile head 12, and the reference position P0 of the plurality of fixing muscles 16 is described. The allowable deviation amount ΔPj from is described in association with the pile diameter.

According to the above configuration, the pile head fixing bar specification includes the allowable deviation amount ΔPj of the plurality of fixing bars 16, so that the designer and the builder of the pile head joint 10 can use the pile head joint 10. Can smoothly proceed with the design and construction.
Preferably, the specification of the fixing muscle for the pile head is associated with the allowable displacement amount ΔPj of the fixing muscle 16, and the attachment of the fixing muscle 16 with respect to the allowable bending moment when the attachment intervals of the fixing muscle 16 are equal. The allowable bending moment ratio (axial force 0 kNM reduction rate) when the spacing is non-uniform is described. The designer and the builder of the pile head joint 10 can further smoothly advance the design and construction of the pile head joint 10 by referring to the ratio.
In addition, regarding the specifications of the fixing head fixing piles, the medium is not limited to the written form, and may be displayed on a display device such as a liquid crystal monitor.

[Side resistance of pile head]
FIG.24 and FIG.25 is a table | surface for demonstrating the design method of the pile head junction part which concerns on other one Embodiment of this invention, As a specification of the pile head junction part 10, in addition to the attachment space | interval of the fixed reinforcement 16 The parameter regarding the side resistance of the pile head 12 is shown. Note that ΔM in FIGS. 24 and 25 is the difference between the first allowable bending moment component sMa1 in the equally spaced arrangement and the first allowable bending moment component sMa1 in the nonuniform arrangement.

In some embodiments, in the allowable bending moment data preparation step S1, the pile head 12 is used as the allowable bending moment data when the mounting intervals of the plurality of fixing bars 16 are not uniform in the circumferential direction of the pile head 12. Prepare allowable bending moment data considering the lateral resistance of pile (side resistance of pile). The side resistance of the pile head 12 is the second allowable bending moment component sMa2 by the mechanism II described above, and is obtained by the equation shown in the above [Equation 1]. 24 and 25 show the pile side resistance values.
Usually, when the installation intervals of a plurality of fixing bars are equal in the circumferential direction of the pile head, the side resistance of the pile head is not taken into account when calculating the allowable bending moment. In particular, when using anchor muscles, the side resistance of the pile head is not taken into consideration. However, when a bending moment acts on the pile head, the side resistance of the pile head actually occurs and functions as a resistance to the bending moment of the pile head. For this reason, it is appropriate to consider the side resistance of the pile head 12 as a part of the allowable bending moment sMa.
Therefore, in the above configuration, when the fixing spacing 16 is not uniform in the circumferential direction of the pile head 12, it is appropriate to prepare allowable bending moment data considering the side resistance of the pile head 12. Allowable bending moment data can be prepared. The allowable bending moment data considering the lateral resistance of the pile head 12 is the sum of the first allowable bending moment component sMa1 and the second allowable bending moment component sMa2, or further considering the third allowable bending moment component sMa3. In the case of entering, the sum of the first allowable bending moment component sMa1, the second allowable bending moment component sMa2, and the third allowable bending moment component sMa3 may be used. Note that, as described above, the allowable bending moment data only needs to correspond to the allowable bending moment, and may be a value that allows for a predetermined remaining force in the allowable bending moment.

In some embodiments, in the specification determination step S3, the allowable bending moment data in consideration of the side resistance of the pile head 12 when the attachment interval of the fixing bars 16 is not uniform in the circumferential direction of the pile head 12 is: The specifications of the pile head joint 10 are determined so that the mounting intervals of the fixing bars are equal in the circumferential direction of the pile head and are equal to or greater than the allowable bending moment when the side resistance of the pile head is not considered. To do. That is, the specification (for example, embedding length hp) of the pile head joint 10 is determined so that the ratio sMa2 / ΔM of the pile side resistance sMa2 to ΔM shown in FIGS.
According to the above configuration, the allowable bending moment data is equal to or greater than the allowable bending moment when the mounting intervals of the plurality of fixing bars are equal and the lateral resistance of the pile head is not considered. Since the specification is determined, the allowable bending moment sMa having a desired size can be realized even if the mounting intervals of the plurality of fixing bars 16 are not uniform.
The allowable bending moment when the mounting intervals of the plurality of fixing bars are equal and the lateral resistance of the pile head is not considered is the first allowable bending when the mounting intervals of the plurality of fixing bars are equal. When the moment component sMa1 or the third allowable bending moment component sMa3 is further taken into consideration, the first allowable bending moment component sMa1 and the third allowable bending moment component sMa3 when the mounting intervals of the plurality of fixing bars are equal intervals, Is the sum of

Here, as is apparent from the equation shown in [Equation 1], the side resistance of the pile head 12 depends on the embedding length hp of the pile head 12 with respect to the foundation concrete portion 4. As shown in FIG. 15, the embedding length hp is the axial length of the pile head portion 12 extending in the foundation concrete portion 4. For example, it can be seen from the example of the pile diameter Dp 600 mm shown in FIG. 24 that the side resistance of the pile head 12 is increased by increasing the embedding length hp.
On the other hand, when the embedding length hp is increased, the amount of excavation around the pile head 12 is increased or the foundation concrete portion 4 is increased. Therefore, the embedding length hp is preferably shorter. For this reason, it is desirable that the ratio hp / Dp of the embedding length hp to the pile diameter Dp which is the outer diameter of the pile 2 is, for example, 0.5 or less.

  In some embodiments, when sMa2 / ΔM is 1 or more, the portion exceeding 1 is not considered as allowable bending moment data. In other words, in calculating the allowable bending moment data, the side resistance of the pile head 12 can only be up to ΔM, which is a reduction from the allowable bending moment when the mounting intervals of the plurality of fixing bars are equal. Do not consider. In this way, it is possible to prevent the allowable bending moment data from being calculated excessively by considering the side resistance of the pile head 12.

[Device for confirming the installation position of anchorage for pile head]
FIG. 26 is a plan view schematically showing an apparatus 50 for confirming an attachment position of a fixing head fixing pile (hereinafter also simply referred to as a position confirmation apparatus) 50 according to an embodiment of the present invention.
The apparatus 50 for position confirmation is used for the construction method of the above-mentioned pile head joint, and is provided on the main body 52, the main body 52 that can be disposed on the pile head 12 and concentrically with the pile head 12, And a mark 54 indicating an allowable deviation amount ΔPj.

According to the above configuration, an operator who performs the fixing work of the fixing muscle 16 arranges the position confirmation device 50 concentrically on the pile head 12 and visually recognizes the mark 54, thereby determining the attachment position of the fixing muscle 16. The attachment work of the fixing bar 16 can be smoothly advanced so that the amount of deviation from the reference position P0 is equal to or less than the allowable deviation amount ΔPj.
For example, the main body 52 is made of a plastic disk, and a plurality of lines are radially drawn on the main body 52 with paint as the marks 54.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
For example, in the above-described embodiment, the allowable bending moment sMa is calculated on the assumption that the crack 44 is generated in the foundation concrete portion 4, but the allowable bending moment is calculated on the assumption that the crack 44 is not generated. It may be calculated. That is, the calculation method of the allowable bending moment sMa is not particularly limited as long as it is considered that the attachment interval of the fixing bars 16 is not uniform.
In addition, in the conventional design drawings and the like, the allowable error of the attachment position of the fixing streaks was sometimes described, but this description only shows the allowable range of the error at the time of construction from the reference position caused by the attachment work. Therefore, the fixing bars are attached at regular intervals determined by a reference position such as a conventional design drawing. The above-described design method of the pile head joint portion of the present embodiment does not limit an error in the construction of the fixing bar 16 from the reference position P0, and the deviation amount from the reference position P0 where the fixing bar 16 should be disposed. An allowable deviation amount ΔPj is defined as the maximum value of. That is, the allowable deviation amount ΔPj defines the maximum deviation amount from the reference position P0 of the fixing muscle 16 that is allowed in order to avoid other reinforcement arrangements other than the fixing muscle 16.
For this reason, it is desirable that the allowable deviation amount ΔPj is larger than an arrangement error during construction, for example, 4 mm or more, more desirably 10 mm or more, and even more desirably 20 mm or more.

  Finally, the method for designing a pile head joint according to the above-described embodiment is an invention related to the method. However, according to the present invention, a program for causing a computer to execute the method is also provided as an invention of an object. Of course it is possible.

DESCRIPTION OF SYMBOLS 1 Structure 2 Pile 4 Foundation concrete part 4a Pile cap 5 Beam 6 Superstructure 8 Pile foundation 10 Pile head joint 12 Pile head 14 Joint member (joint coupler)
16 Fixing bar 17 Concrete part 18 End plate 19 Outer steel pipe 20 Shaft part 21 Screw part 22 Fixing body 23 Lower protrusion part 24 Upper protrusion part 26 Screw hole 28 Notch 29 Fork part 30 Connection part 32 Reinforcement beam part 34 Reinforcement rib Part 35 Curved surface 36 Groove surface 38 Weld bead 40 Upper part 42 Lower part 44 Crack 50 Device for confirming the attachment position of fixing muscle for pile head (position confirmation device)
52 Body 54 Mark S1 Allowable Bending Moment Data Preparation Step S2 Generated Bending Moment Calculation Step S3 Specification Determination Step S4 Ratio Preparation Step S5 Anchor Placement Step S6 Concrete Placing Step S10 Database Access Step

Claims (11)

Pile head joint design comprising a pile head, a plurality of anchoring bars arranged around the pile head, and a foundation concrete part constituted by concrete surrounding the pile head and the plurality of anchoring bars In the method
An allowable bending moment data preparation step of preparing allowable bending moment data corresponding to the allowable bending moment of the pile head joint,
A generated bending moment calculating step for calculating a generated bending moment generated in the pile head; and
A specification determining step for determining the specifications of the pile head joint so that the generated bending moment is equal to or less than the allowable bending moment data;
With
In the permissible bending moment data preparation step, prepare permissible bending moment data when the mounting intervals of the plurality of fixing bars in the circumferential direction of the pile head are non-uniform,
In the specification determining step, as the mounting condition of the plurality of fixing bars, when the mounting positions when the plurality of fixing bars are mounted at equal intervals in the circumferential direction of the pile head are used as the reference position, A method for designing a pile head joint, wherein an allowable deviation amount of the attachment positions of the plurality of fixing muscles relative to the head from the reference position is determined. 2. The pile according to claim 1, wherein in the specification determining step, the allowable displacement amount is determined in consideration of a displacement direction of each of the fixing bars as an attachment condition of the plurality of fixing bars. Head joint design method. In the specification determining step, the allowable bending moment data of the pile head joint when the mounting intervals of the plurality of fixing bars are uneven is the allowable bending when the mounting intervals of the plurality of fixing bars are equal. The method for designing a pile head joint according to claim 1 or 2, wherein the specification of the pile head joint is determined so as to be equal to or greater than a predetermined ratio compared to a moment. The allowable bending moment data preparation step includes a database access step of accessing a database in which the mounting intervals of the plurality of fixing bars and the allowable bending moment of the pile head joint are stored in association with each other,
The pile head joint design method according to any one of claims 1 to 3, wherein the allowable bending moment data is selected from the database in the allowable bending moment data preparation step. A ratio for preparing a ratio of an allowable bending moment when the mounting intervals of the plurality of fixing bars are not uniform with respect to an allowable bending moment when the mounting intervals of the plurality of fixing bars are equal intervals under a predetermined axial force A preparation process,
2. The permissible bending moment data preparing step, wherein the permissible bending moment data is prepared by multiplying the permissible bending moment when the mounting intervals of the plurality of fixing bars are equal intervals by the ratio. The design method of the pile head junction part of any one of thru | or 3. 6. The allowable bending moment data preparing step, wherein the allowable bending moment data considering the side resistance of the pile head is prepared as the allowable bending moment data. Design method for pile head joints. In the specification determining step, the pile may be set such that the allowable bending moment data is equal to or greater than the allowable bending moment when the mounting intervals of the plurality of fixing bars are equal and the lateral resistance of the pile head is not considered. The method for designing a pile head joint according to claim 6, wherein specifications of the head joint are determined. Construction of a pile head joint comprising a pile head, a plurality of anchoring bars arranged around the pile head, and a foundation concrete portion constituted by concrete surrounding the pile head and the plurality of anchoring bars In the method
A fixing muscle attaching step for attaching the plurality of fixing muscles in a circumferential direction of the pile head;
In the fixing muscle attaching step,
Each of the plurality of fixing muscles with respect to the pile head when the attachment positions of the plurality of fixing muscles when the plurality of fixing muscles are attached at equal intervals in the circumferential direction of the pile head A method for constructing a pile head joint, wherein the plurality of fixing bars are attached such that a deviation amount of the attachment position from the reference position is equal to or less than a predetermined allowable deviation amount. Pile head joint design comprising a pile head, a plurality of anchoring bars arranged around the pile head, and a foundation concrete part constituted by concrete surrounding the pile head and the plurality of anchoring bars In the plan view of the pile head joint that is referred to by an operator who carries out the arrangement of the plurality of fixing muscles,
Each of the plurality of fixing muscles with respect to the pile head when the attachment positions of the plurality of fixing muscles when the plurality of fixing muscles are attached at equal intervals in the circumferential direction of the pile head The design drawing of the pile head joint part characterized by including the allowable deviation | shift amount from the said reference position of the attachment position of. In the specification sheet for anchors for pile heads, which describes the specifications of multiple anchors placed around the pile head,
Each of the plurality of fixing muscles with respect to the pile head when the attachment positions of the plurality of fixing muscles when the plurality of fixing muscles are attached at equal intervals in the circumferential direction of the pile head A specification for a fixing rod for a pile head, wherein an allowable deviation amount from the reference position of the mounting position is described. A device for confirming the mounting position of fixing bars for pile heads used in the construction method for pile head joints according to claim 8,
A body that can be placed concentrically with the pile head on the pile head;
A mark provided on the main body and indicating the allowable deviation amount;
A device for confirming the attachment position of a fixing muscle for a pile head, comprising:

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