JP7735621B2 - Pile cap joint structure - Google Patents

Description

The present invention relates to a pile head joint structure.

In the pile head joint structure between the pile head and pile cap, the pile head anchorage reinforcement that extends upward from the pile head is buried within the pile cap, and pile cap reinforcement such as bracing bars, base reinforcement, and horizontal reinforcement are buried within the pile cap. This means that various rebars become overly densely intertwined within the pile cap, posing issues such as the impossibility or difficulty of rebar placement during construction.

Here, an example of a conventional pile head joint structure 100 will be described with reference to Figures 1 and 2. Figure 1 is a longitudinal cross-sectional view of the conventional pile head joint structure, and Figure 2 is a cross-sectional view taken along the line II-II in Figure 1, cut at the level of the lower end main reinforcement of the foundation beam.

The pile forming the pile head joint structure 100 in the illustrated example is a prefabricated pile 10 (SC pile, a high-strength concrete pile with an outer steel pipe), in which a cylindrical high-strength concrete pile 12 is placed inside a cylindrical steel pipe 11 by centrifugal compaction. The lower ends of multiple pile head anchorage bars 17 are fixed to the upper outer surface 13 of the steel pipe 11 by flare welding or the like at intervals around the circumference, and the multiple pile head anchorage bars 17 protrude upward from the top end 15 of the SC pile 10. The multiple pile head anchorage bars 17 may be welded at their lower ends to an end steel plate (not shown) provided at the top end 15 of the SC pile 10, or may be threadedly connected to a joint coupler (not shown) attached to the upper outer surface of the steel pipe 11. In either case, multiple pile head anchorage bars 17 are fixed at intervals around the circumference of the pile, which is circular in plan view.

The pile head 14 of the SC pile 10 installed in the ground G is embedded within the underside 21 of a cubic (or rectangular) reinforced concrete pile cap 20. Inside the pile cap 20, as shown in Figures 1 and 2, a plurality of U-shaped base reinforcement bars 25 are arranged below the pile cap 20 to form a grid pattern in plan view, and as shown in Figure 1, a plurality of U-shaped bar reinforcement bars 26 are arranged above the pile cap 20 to form a grid pattern in plan view, and as shown in Figure 1 and 2, parallel horizontal reinforcement bars 27 are arranged on the four side surfaces 22. The rising portions of the base reinforcement bars 25 and the hanging portions of the bar reinforcement bars 26 overlap each other by a predetermined length.

As shown in Figure 2, in the illustrated example, reinforced concrete foundation beams 30 are fixed to three of the four side surfaces 22 of the pile cap 20, extending laterally from those surfaces. As shown in Figures 1 and 2, multiple upper end main reinforcements 31 and lower end main reinforcements 32 of each foundation beam 30 are fixed inside the pile cap 20.

As shown in Figures 1 and 2, a square column 40 made of reinforced concrete and having a square shape in plan view (an example of a rectangle in plan view) is fixed to the top surface 23 of the pile cap 20, and multiple main column reinforcements 41 are arranged inside the square column 40 along the outline of the square shape in plan view and are fixed from the top surface 23 to the interior of the pile cap 20.

As is clear from Figure 2, inside the pile cap 20, particularly at the bottom, the base reinforcement 25 arranged in a grid pattern, the lower end main reinforcement 32 of each foundation beam 30, and multiple column main reinforcement 41 arranged along the outline of a square in plan view are intertwined, and multiple pile head anchorage reinforcement 17 arranged circumferentially around the circle in plan view are also intertwined.

The base reinforcement 25 and lower end main reinforcement 32 all extend in the X-axis and Y-axis directions, which are perpendicular to each other in plan view, and the multiple column main reinforcement 41 extend along the Z-axis, which is perpendicular to the X-Y plane, and are arranged on a rectangular outline parallel to the X-axis and Y-axis. In other words, the base reinforcement 25, lower end main reinforcement 32, and column main reinforcement 41 are all arranged in a lattice pattern parallel to the X-axis and Y-axis in plan view.

For these various rebars, multiple pile head anchorage bars 17 are arranged circumferentially in a circular plan view. This means they are prone to interference with the base reinforcement 25, bottom end main reinforcement 32, and column main reinforcement 41, particularly the bottom end main reinforcement 32. For example, in Figure 2, of the eight pile head anchorage bars 17, six of them, indicated by dotted lines, are anchorage bars that interfere with other rebars. This makes rebar placement difficult because other rebars must be placed to avoid interference with the pile head anchorage bars 17. For example, if adjacent bottom end main reinforcement bars 32 are closely spaced to avoid interference with the pile head anchorage bars 17, this can hinder the concrete's ability to fill the pile cap 20 during construction, leading to various issues, such as the creation of voids below the densely spaced reinforcement where concrete is not filled.

For these reasons, in a pile head joint structure in which multiple pile head anchorage rebars protruding above the pile head of the pile are embedded in a rectangular concrete pile cap in plan view, there is a need for a pile head joint structure equipped with a pile cap that is easy to arrange reinforcement and of high quality, without the risk of interference between the pile head anchorage rebars and the pile cap rebars or the lower end main reinforcement of the foundation beams, which are embedded in a grid pattern inside the pile cap in plan view.

Patent Document 1 proposes a pile head joint structure for concrete-filled steel pipe piles. Specifically, the structure includes multiple pile head reinforcing bars arranged at equal intervals along the outer periphery of the steel pipe at the pile head and embedded in the foundation concrete. The structure also includes a steel bracket with a pair of opposing plate-shaped support sections arranged along the outer periphery of the steel pipe at the pile head in alignment with the arrangement of the pile head reinforcing bars. The pile-side joint end of one of the plate-shaped support sections is welded vertically to the outer periphery of the steel pipe, and the rebar-side joint end of the other end is joined to the vertically oriented pile head reinforcing bars via a jointing means. The relationship between the tensile yield strength (pTy) of the steel pipe pile and the tensile yield strength (n × rTy) of the total number of pile head reinforcing bars (n) satisfies α × pTy ≥ n × rTy, taking into account the reduction rate (α) of the out-of-plane bending resistance of the steel pipe pile due to the outer diameter of the concrete-filled steel pipe and the bracket to which the pile head reinforcing bars are joined.

Patent No. 6335100

Even in the pile head joint structure of the concrete-reinforced steel pipe pile described in Patent Document 1, the pile head reinforcing bars are fixed to multiple steel brackets arranged circumferentially in a circular plan view. This means that multiple pile head reinforcing bars arranged circumferentially with a diameter larger than the outer diameter of the concrete-reinforced steel pipe pile are embedded in the foundation concrete. As a result, the problem of interference with other reinforcing bars arranged in a grid pattern in a plan view inside the foundation concrete (in the above example, reinforcing bars equivalent to the pile cap reinforcing bars and the lower end main reinforcing bars of the foundation beam) remains.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a pile head joint structure in which multiple pile head anchorage rebars protruding above the pile head of the pile are embedded in a concrete pile cap that is rectangular in plan view. The purpose of the present invention is to provide a pile head joint structure with a pile cap that is easy to arrange reinforcement and has excellent quality, and in which there is no risk of interference between the pile head anchorage rebars and the pile cap rebars or the lower end main reinforcement of the foundation beams that are embedded in a grid pattern inside the pile cap in plan view.

In order to achieve the above object, one aspect of the pile head joint structure according to the present invention is as follows:
The pile head anchoring bar is provided with a rectangular steel cylindrical member in plan view, which is arranged around the pile head of a circular pile in plan view, and a plurality of pile head anchoring bars fixed to each side plate of the cylindrical member and protruding upward.
A concrete pile cap having a rectangular shape in plan view and equipped with pile cap reinforcement arranged in a grid pattern in plan view is disposed above the pile, and the pile head anchoring reinforcement is fixed inside the pile cap.

In this configuration, a rectangular steel tubular member (in plan view) is arranged around the pile head of a circular pile. Multiple pile head anchorage rebars, fixed to each side panel of the tubular member, are embedded inside the pile cap, resulting in the multiple pile head anchorage rebars being positioned along the rectangular outline in plan view. In other words, unlike conventional pile head joint structures, they are not positioned along the circumferential direction of the circular pile in plan view. This reduces or prevents interference between the pile cap reinforcement, which is embedded in a grid pattern inside the pile cap in plan view, and the pile head anchorage rebars positioned along the rectangular outline in plan view. This improves the ease of rebar placement, and also improves the concrete filling during pile cap construction due to the lack of gap-free rebar placement, resulting in a high-quality pile cap-equipped joint structure.

In addition, compared to conventional structures in which the pile head anchorage bars are fixed to the outer periphery of the pile, the pile head anchorage bars are fixed to square tubular members with larger planar dimensions than the piles, which increases the distance between the piles and each pile head anchorage bar in plan view (increasing the distance between stress centers), and due to the longer stress center distance, it becomes possible to reduce the number of pile head anchorage bars compared to conventional structures.

Here, the "rectangular plan view" of the planar shape of the steel rectangular tubular member and the pile cap includes a square plan view and a rectangular plan view. For example, they should be aligned so that the center of the circular pile in plan view, the centroid of the square tubular member in plan view, and the centroid of the square pile cap in plan view coincide, and they should be aligned so that each side of the rectangular tubular member in plan view and the corresponding side of the pile cap are parallel to each other.

As mentioned above, pile cap reinforcement includes various types of reinforcing bars, such as bracing bars, base bars, and horizontal reinforcement bars. Furthermore, the pile cap anchorage bars may be fixed to the inner surface of each side plate of the rectangular tubular member, or to the outer surface of each side plate. The fixing method may be welding, such as flare welding, or by screwing the lower end of the pile cap anchorage bars into joint couplers fixed to each side plate.

Furthermore, it is preferable to embed a portion of the pile head and the upper part of the square tubular member inside the pile cap, and then embed the pile head anchoring reinforcement inside the pile cap, as this integrates the pile head, square tubular member, and pile cap.

Another aspect of the pile head joint structure according to the present invention is as follows:
The gap between the inner surface of the square tube member and the outer surface of the pile is filled with a filler material that hardens.

In this case, the gap between the inner surface of the square tube member and the outer surface of the pile (outer surface of the pile head) is filled and hardened with filler, which integrates the square tube member and the pile, improving stress transfer between the pile and pile cap and creating a pile head joint structure with even higher joint strength. Furthermore, during construction, the square tube member is placed in the excavated area around the pile that has already been installed in the ground, and various pile cap reinforcement and other components are then placed on top of it. During construction, the square tube member can be positioned relative to the pile head using the filler.

Another aspect of the pile head joint structure according to the present invention is as follows:
The filler is characterized in that it is non-shrinkage mortar.

In this embodiment, the filler that fills and hardens in the gap between the inner surface of the square tube member and the outer surface of the pile is non-shrinkage mortar, which suppresses drying shrinkage of the filler and reduces the occurrence of gaps between the inner surface of the square tube member and the outer surface of the pile. For example, when using ordinary concrete or mortar as the filler, there is a risk of drying shrinkage, and the drying shrinkage of the filler can create gaps between the pile and the filler, or between the square tube member and the filler, making it impossible to ensure the integrity of the pile and the square tube member via the filler. However, using non-shrinkage mortar eliminates this issue.

In another aspect of the pile head joint structure according to the present invention,
A shear key is attached to at least one of the inner surface of the square tube member and the outer surface of the pile, and the shear key is embedded inside the filler material.

In this embodiment, a shear key is attached to at least one of the inner surface of the square tubular member and the outer surface of the pile, and the shear key is embedded inside the filler material. This improves stress transmission between the pile and pile cap due to the shear resistance of the shear key, resulting in a pile head joint structure with even stronger joint strength. Here, "a shear key is attached to at least one of the inner surface of the square tubular member and the outer surface of the pile" includes a configuration in which a shear key is attached to both, and a configuration in which a shear key is attached to one of the two.

In another aspect of the pile head joint structure according to the present invention,
The square tube member is characterized in that it is formed from either a square steel pipe or a joint of multiple steel plates.

In this embodiment, the square tube member is formed from a square steel pipe, which makes it relatively easy to manufacture the square tube member by cutting a regular square steel pipe to the desired length. Meanwhile, the square tube member is formed from a joint made by welding multiple steel plates (four steel plates, two L-shaped steel plates, one L-shaped steel plate and two steel plates, etc.), which allows for a variety of shapes and configurations for the square tube member, such as joining steel plates of different thicknesses.

In another aspect of the pile head joint structure according to the present invention,
The pile cap is characterized in that the main beam reinforcement of the concrete foundation beam extends from at least one side surface of the pile cap to the inside.

According to this aspect, even when the main beam reinforcement of the foundation beam (upper end main reinforcement and lower end main reinforcement) extends inward from the side of the pile cap, interference between the multiple pile head anchorage reinforcement protruding upward from the side of the rectangular tubular member and the main beam reinforcement can be suppressed or prevented. Here, "the main beam reinforcement of the foundation beam extends inward from at least one side of the pile cap" includes configurations in which the main beam reinforcement extends to the pile cap from a foundation beam fixed to all four sides of a pile cap that is rectangular (cubic or rectangular parallelepiped) in plan view, as well as configurations in which the main beam reinforcement extends to the pile cap from a foundation beam fixed to any three, any two, or any one side.

In another aspect of the pile head joint structure according to the present invention,
A concrete rectangular pillar in plan view is erected on the upper surface of the pile cap,
A plurality of main column reinforcements arranged inside the rectangular column along the outline of a rectangle in plan view extend from the top surface of the pile cap to the inside.

According to this aspect, even when multiple column main reinforcements arranged along the outline of a rectangle in plan view inside a square column extend from the top surface of the pile cap to the interior, it is possible to suppress or prevent interference between the multiple pile cap anchorage reinforcements protruding upward from the side of the square tubular member and the column main reinforcement. In the case of a seismically isolated building, the reinforcing bars of the seismic isolation device extend from the top surface of the pile cap to the interior instead of the square column or column main reinforcement. In this specification, the reinforcing bars of this seismic isolation device are considered to be steel bars equivalent to the column main reinforcement described above.

In another aspect of the pile head joint structure according to the present invention,
The pile is characterized in that it is one of prefabricated piles including at least steel pipe piles, PHC piles, PRC piles, and SC piles, and cast-in-place piles.

According to this method, regardless of whether the pile is a precast pile or a cast-in-place pile, the pile head anchoring reinforcement is not fixed directly to the pile, making it possible to arrange the pile head anchoring reinforcement around the pile heads of piles of various shapes.

As can be seen from the above explanation, the pile head joint structure of the present invention has multiple pile head anchorage rebars protruding above the pile head of the pile, which are embedded in a concrete pile cap that is rectangular in plan view. This eliminates the risk of interference between the pile head anchorage rebars and the pile cap rebars or the lower end main reinforcement of the foundation beams, which are embedded in a grid pattern inside the pile cap in plan view, making it possible to provide a pile head joint structure with a pile cap that is easy to arrange reinforcement and has excellent quality.

FIG. 1 is a longitudinal cross-sectional view of an example of a conventional pile head joint structure. 2 is a cross-sectional view taken along the line II-II in FIG. 1, taken at the level of the lower end main reinforcement of the foundation beam. FIG. 1 is a longitudinal cross-sectional view of an example of a pile head joint structure according to an embodiment. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3, taken at the level of the lower end main reinforcement of the foundation beam. 4 is a cross-sectional view taken along the VV arrow in FIG. 3, cut at the midpoint of the pile cap. FIG. 10 is a vertical cross-sectional view of another example of a pile head joint structure according to an embodiment. FIG. 1 is a process diagram of an example of a construction method for a pile head joint structure according to an embodiment. Continuing from FIG. 7, this is a process diagram of an example of a construction method for a pile head joint structure according to an embodiment.

Below, an example of a pile head joint structure according to an embodiment will be described with reference to the attached drawings, along with a construction method for the pile head joint structure. Note that in this specification and drawings, substantially identical components will be assigned the same reference numerals, and redundant explanations may be omitted.

[Pile head joint structure according to the embodiment]
First, an example of a pile head joint structure according to the first embodiment will be described with reference to Figures 3 to 6. Here, Figure 3 is a longitudinal cross-sectional view of an example of a pile head joint structure according to the embodiment. Also, Figure 4 is a view taken along arrows IV-IV in Figure 3, which is a cross-sectional view cut at the level of the lower end main reinforcement of the foundation beam, and Figure 5 is a view taken along arrows V-V in Figure 3, which is a cross-sectional view cut at the midpoint of the pile head. Furthermore, Figure 6 is a longitudinal cross-sectional view of another example of a pile head joint structure according to the embodiment.

As already explained with reference to Figures 1 and 2, in the conventional pile head joint structure 100, multiple pile head anchoring bars 17 are welded to the upper outer surface 13 of the SC pile 10 at intervals around its circumference. In contrast, the pile head joint structure 200 shown in Figure 3 differs in that, instead of directly fixing the pile head anchoring bars 17 to the upper outer surface 13 of the SC pile 10, multiple pile head anchoring bars 17 are welded to each side plate 51 of a steel square tubular member 50 that is rectangular in plan view and arranged around the pile head 14 of the pile 10.

The pile cap 20 in the illustrated example is a cube, and the rectangular tube member 50 has a square shape in plan view. The rectangular tube member 50 is formed, for example, from a square steel pipe.

In addition, the pile 10 is an SC pile, which is a type of precast pile, but it may also be made of steel pipe piles other than SC piles, PHC piles, PRC piles, etc., or it may be a cast-in-place pile.

As shown in Figure 5, pile head anchoring bars 17 are fixed to the inner surfaces 55 of the four side plates 51 of the rectangular tubular member 50 by flare welding or the like. In the illustrated example, eight pile head anchoring bars 17 are fixed to a total of eight locations: the four corners and the center of each side plate 51; however, the fixing locations and number of pile head anchoring bars 17 are not limited to the illustrated example. In particular, compared to conventional structures in which the pile head anchoring bars 17 are fixed directly to the piles, the distance between the pile 10 and each pile head anchoring bar 17 in plan view is longer. As a result of the longer stress center distance, the number of pile head anchoring bars 17 can be reduced compared to conventional pile head joint structures.

As shown in Figure 5, the square tube member 50 is arranged so that the center O of the SC pile 10 coincides with the centroid O of the square tube member 50, and each side surface 22 of the pile cap 20 and each corresponding side plate 51 of the square tube member 50 are parallel to each other. When the square tube member 50 is arranged in this manner, as shown in Figure 5, each side plate 51 of the square tube member 50 is perpendicular to the longitudinal direction of the corresponding foundation beam 30.

As a result, as shown in Figure 4, interference between the base reinforcement 25 of the pile cap 20, which is square in plan view, and the lower end main reinforcement 32 (an example of a beam main reinforcement) of the foundation beam 30 extending inside the pile cap 20, and each pile head anchorage reinforcement 17 fixed to each side plate 51 of the square tubular member 50 is suppressed or prevented.

Specifically, as shown in Figure 4, the base reinforcement 25 is arranged in a grid pattern (X-axis and Y-axis directions) inside the pile cap 20 when viewed from above, and the lower end main reinforcement 32 of the foundation beam 30 also extends along the X-axis and Y-axis directions inside the pile cap 20 when viewed from above.

In contrast, in the pile head joint structure 200, the pile head anchoring reinforcement 17 is aligned along each side plate 51 parallel to the X-axis and Y-axis directions of the square tubular member 50, which is square in plan view, rather than along the outer periphery of the SC pile 10, which is circular in plan view. This makes it less likely to interfere with the base reinforcement 25 and lower end main reinforcement 32, which also extend in the X-axis and Y-axis directions.

In addition, in the pile head joint structure 200, filler material 60 is filled and hardened between the inner surface 55 of the square tube member 50 and the upper outer surface 13 of the SC pile 10.

By filling and hardening the gap between the inner surface 55 of the square tube member 50 and the upper outer surface 13 of the SC pile 10, the square tube member 50 and the SC pile 10 are integrated, improving stress transfer between the SC pile 10 and the pile cap 20, and forming a pile head joint structure 200 with even stronger joint strength.

Here, non-shrinkage mortar is suitable as the filler 60. Using non-shrinkage mortar as the filler 60 suppresses drying shrinkage of the filler 60, and prevents gaps caused by drying shrinkage of the filler between the inner surface 55 of the square tube member 50 and the upper outer surface 13 of the SC pile 10.

Also, as shown in Figure 6, in the pile head joint structure 200A, shear keys 58, 18 may be attached to both the inner surface 55 of the square tube member 50 and the upper outer surface 13 of the SC pile 10, and the shear keys 58, 18 may be embedded inside the filler material 60.

In this way, both the square tube member 50 and the SC pile 10 are equipped with shear keys 58, 18, and the shear keys 58, 18 are embedded inside the filler material 60. This improves stress transmission between the SC pile 10 and the pile cap 20 due to the shear resistance of the shear keys 58, 18, resulting in a pile head joint structure 200A with even stronger joint strength.

[Construction method of pile head joint structure according to the embodiment]
Next, an example of a construction method for a pile head joint structure according to the embodiment will be described with reference to Figures 7, 8, and 3. Figures 7, 8, and 3 are process diagrams of an example of a construction method for a pile head joint structure according to the embodiment, respectively. Figures 4, 5, etc. will also be referenced as appropriate.

As shown in Figure 7, first, SC piles 10 are installed in the ground G. There are various installation methods for SC piles 10 depending on the properties of the ground G and the surrounding environment, and methods such as driving and embedding (pre-boring, core excavation, rotation, etc.) can be used.

After installing the SC pile 10 in the ground G, the surface of the ground G is excavated to expose the pile head 14. Next, square tubular members 50, with pile head anchoring reinforcement 17 fixed to the inner surface 55 of each side panel 51, are arranged around the pile head 14 and placed on the excavated bedding surface.

As already explained with reference to Figure 5, the square tube member 50 is positioned relative to the SC pile 10 so that the center O of the SC pile 10 coincides with the centroid O of the square tube member 50, and the side surfaces 22 of the pile cap 20 and the corresponding side panels 51 of the square tube member 50 are parallel to each other.

Then, to prevent the aligned square tube member 50 from shifting, filler material 60 is filled into the gap between the inner surface 55 of the square tube member 50 and the upper outer surface 13 of the SC pile 10. That is, as already explained, filling the gap between the square tube member 50 and the SC pile 10 with filler material 60 is intended to improve stress transfer between the SC pile 10 and the pile cap 20 from a structural standpoint, and to prevent the aligned square tube member 50 from shifting from a construction standpoint.

After the filled filler 60 has hardened, as shown in Figure 8, the base reinforcement 25, bracing bars 26, and horizontal reinforcement bars 27 (all pile cap reinforcement) of the pile cap 20 are placed so as not to interfere with the pile head anchorage bars 17, and the main beam reinforcement 31, 32 of the foundation beam 30 are placed, followed by the main column reinforcement 41 of the column 40.

As already explained with reference to Figure 4, the base reinforcement 25 is arranged in a grid pattern (in the X-axis and Y-axis directions) inside the pile cap 20 when viewed from above, and the lower end main reinforcement 32 of the foundation beam 30 also extends from the X-axis and Y-axis directions inside the pile cap 20 when viewed from above. Furthermore, since the pile head anchorage reinforcement 17 is aligned along the side panels 51 of the rectangular tubular member 50 that are parallel to the X-axis and Y-axis directions, the base reinforcement 25 and lower end main reinforcement 32, which also extend in the X-axis and Y-axis directions, are less likely to interfere with the pile head anchorage reinforcement 17, improving the workability of arranging the reinforcing bars.

After the reinforcing bars of each component have been arranged, concrete is poured in the following order: pile cap 20, foundation beam 30, and column 40. The pile head joint structure 200 shown in Figure 3 is constructed by allowing the fresh concrete to harden.

In this way, the construction method for the pile head joint structure 200 not only improves the ease of reinforcing bar placement, but also eliminates the dense tangle of reinforcing bars, improving the filling properties of concrete, making it possible to construct a pile head joint structure 200 equipped with a high-quality pile cap.

Other embodiments may be possible in which other components are combined with the configurations described in the above embodiments, and the present invention is in no way limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately depending on the application form.

10: SC piles (piles, prefabricated piles)
11: Steel pipe 12: High-strength concrete 13: Upper outer surface 14: Pile head 15: Top 17: Pile head anchorage reinforcement 18: Share key 20: Pile cap 21: Bottom surface 22: Side surface 23: Top surface 25: Base reinforcement (pile cap reinforcement)
26: Hakama muscle (pile cap muscle)
27: Lateral reinforcement 30: Foundation beam 31: Top main reinforcement (beam main reinforcement)
32: Bottom main reinforcement (beam main reinforcement)
40: Column 41: Column main reinforcement 50: Square tube member 51: Side plate 55: Inner surface 58: Share key 60: Filler (non-shrinkage mortar)
200, 200A: Pile cap joint structure G: Ground

Claims (8)

The pile head anchoring bar is provided with a rectangular steel cylindrical member in plan view, which is arranged around the pile head of a circular pile in plan view, and a plurality of pile head anchoring bars fixed to each side plate of the cylindrical member and protruding upward.
A pile head joint structure characterized in that a concrete pile cap having a rectangular shape in plan view and pile cap reinforcement arranged in a grid pattern in plan view is placed above the pile, the square tubular member is embedded in the pile cap so that its upper part is at a height that does not interfere with the pile cap reinforcement, and the pile head anchoring reinforcement is fixed inside the pile cap. The pile head joint structure described in claim 1, characterized in that a filler material is filled and hardened in the gap between the inner surface of the rectangular tube member and the outer surface of the pile. The pile head joint structure described in claim 2, characterized in that the filler material is non-shrinkage mortar. A pile head joint structure as described in claim 2 or 3, characterized in that a shear key is attached to at least one of the inner surface of the rectangular tubular member and the outer surface of the pile, and the shear key is embedded inside the filler material. A pile head joint structure as described in any one of claims 1 to 4, characterized in that the square tube member is formed from either a square steel pipe or a joint of multiple steel plates. A pile head joint structure as described in any one of claims 1 to 5, characterized in that the main beam reinforcement of the concrete foundation beam extends from at least one side of the pile cap to the interior. A concrete rectangular pillar in plan view is erected on the upper surface of the pile cap,
A pile head joint structure according to any one of claims 1 to 6, characterized in that a plurality of column main reinforcements arranged inside the square column along the outline of a rectangle in a plan view extend from the top surface of the pile cap to the inside. The pile head joint structure described in any one of claims 1 to 7, characterized in that the pile is one of precast piles, including at least a steel pipe pile, a PHC pile, a PRC pile, and a SC pile, and a cast-in-place pile.