Pile-column joint structure and construction method

Abstract

To provide a joint structure of a pile and a column and a method for constructing the same, which eliminate the need for footings and foundation beams, reduce the amount of excavated soil and the amount of steel frames used, simplify the structure, and reduce costs, in which bending force generated in the joint can be reduced by making the joint form a semi-rigid joint, and rationality and economic efficiency can be improved.SOLUTION: A joint structure of a pile 1 has a hollow cross section and a column 2 is provided, in which at a lower end of the column 2, a base plate 21 and a shear key 23 extending downward from the base plate 21 and inserted into an upper end of the pile 1 and having an outer dimension smaller than that of the column 2 are provided. A space from the upper end of the pile 1 to the lower surface of the base plate 21 is filled with concrete 4 so as to cover the periphery of the shear key 23.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a joint structure between a pile having a hollow cross section and a column, and a construction method thereof. [Background technology]

[0002] A commonly used method for connecting piles to the superstructure is to use reinforced concrete foundation footings or foundation beams, but this requires complicated reinforcement work and increases the amount of soil excavated from the ground, which hinders efforts to reduce costs and shorten construction periods.

[0003] Therefore, in order to eliminate the need for foundation footings and foundation beams and reduce the amount of excavated soil, for example, Patent Document 1 discloses a pile-column joint structure and construction method in which a pile head joint metal is fixed to the pile head and fastened to the base plate of the column base to join the pile head and column base. In this method, the column base is extended below the base plate, inserted into the hollow part of the pile head, and fixed with concrete, so that the pile and column can be joined reliably, firmly, and simply. In addition, it is easy to adjust the level of the column and correct the positional deviation of the pile.

[0004] Patent Document 2 also discloses a joining structure and method for connecting a pile to a superstructure, in which a cap steel pipe (joining jig) consisting of a base plate joined to the base of a steel column or a concrete-filled steel pipe column and a steel pipe joined to the underside of the base plate is placed over the top of a steel pipe pile or a precast concrete pile, and concrete is filled into the gap to integrate the pile and the column to form a rigid joint. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-295286 A [Patent Document 2] JP 2007-009438 A [Non-patent literature]

[0006] [Non-Patent Document 1] Architectural Institute of Japan, "Guidelines and Commentary on Composite Structure Design 2010," Architectural Institute of Japan, November 2010, p. 38 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the joint structure disclosed in Patent Document 1, in order to secure the anchoring strength between the pile and the column and to rigidly join them, it is necessary to provide a stud in the column base extension that is inserted into the hollow part of the pile head. In addition, the shape of the pile head joint metal that is fixed to the pile head is complicated, and it is time-consuming to manufacture it. Furthermore, when inserting the column base into the hollow part of the pile head to erect the column, it is also necessary to temporarily support the column with a wire.

[0008] Furthermore, in the joint structure disclosed in Patent Document 2, in order to rigidly connect the pile and the column, the diameter of the cap steel pipe needs to be approximately the pile diameter + 300 mm, and the embedded length of the pile into the cap steel pipe needs to be approximately 1.5 times the pile diameter or more. Therefore, as the pile diameter increases, the diameter and height of the cap steel pipe that covers the pile also increase. As a result, the amount of soil that needs to be excavated increases, and transporting the cap steel pipe to the site also requires effort.

[0009] The present invention has been made to solve the above-mentioned problems, and has an object to provide a pile-to-column joint structure and its construction method which eliminates the need for footings and foundation beams, reduces the amount of excavated soil and steel used, thereby simplifying the structure and reducing costs, and uses a semi-rigid joint between the pile and the column rather than a rigid joint as in Patent Document 1 or Patent Document 2, thereby reducing the bending moment transmitted from the upper column to the joint, thereby improving rationality and economy. [Means for solving the problem]

[0010] The means for solving the above problems are as follows. [1] A joint structure between a hollow cross-section pile and a column, wherein the lower end of the column is provided with a base plate and a shear key having outer dimensions smaller than that of the column, extending downward from the base plate and inserted into the upper end of the pile, and the space from the upper end of the pile to the underside of the base plate is filled with concrete to cover the periphery of the shear key. [2] The shear key is provided with a support plate protruding laterally, and the upper end of the pile is provided with a protrusion that protrudes inward beyond the inner surface of the pile. This is a joint structure between a pile and a column as described in [1]. [3] The joint structure between a pile and a column described in [2], wherein the protrusion consists of a slip-stop plate fixed to multiple points circumferentially around the upper end of the pile. [4] The joint structure between a pile and a column described in [2], wherein the protrusion consists of an end plate provided at the upper end of the pile. [5] A pile-column joint structure described in any one of [1] to [4], wherein a stiffener is provided between the base plate and the shear key. [6] A pile-column joint structure described in any one of [1] to [5], wherein an engagement portion is provided on the underside of the base plate to engage with the concrete. [7] A joint structure between a pile and a column described in any of [1] to [6], further comprising an anchor frame installed on the ground so as to surround the upper end of the pile, and the column is positioned relative to the pile by fastening the base plate to an anchor bolt provided on the anchor frame. [8] A construction method for a joint structure between a pile and a column described in any one of [1] to [6], comprising the steps of: erecting the column so that the shear key of the column is inserted into the upper end of the pile installed in the ground; installing a formwork to surround the outer periphery of the upper end of the pile; and filling the space from the upper end of the pile to the underside of the base plate with concrete so as to cover the periphery of the shear key. [9] A construction method for the pile-to-column joint structure described in [7], comprising the steps of: installing the anchor frame on the ground so as to surround the upper end of the pile installed in the ground; erecting the column so that the shear key of the column is inserted into the upper end of the pile; installing a formwork to surround the outer periphery of the upper end of the pile; and filling the space from the upper end of the pile to the underside of the base plate with concrete so as to cover the periphery of the shear key.

[10] A construction method for a pile-column joint structure described in [8] or [9], wherein the formwork is a disposable formwork. Effect of the Invention

[0011] According to the pile-to-column joint structure and its construction method of the present invention, it is possible to simplify the structure and reduce costs by reducing the amount of excavated soil and the amount of steel used, and by adjusting the joint form to a semi-rigid joint, it is possible to reduce the bending moment transmitted to the joint from the upper column, further improving rationality and economy.

[0012] In addition, since the outer dimensions of the shear key are smaller than the outer dimensions of the column, it becomes easier to accommodate eccentricity of the column relative to the pile, thereby increasing design freedom and ease of construction. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing an example of a building to which the pile-column joint structure of the present invention is applied. [Diagram 2] FIG. 2 is a vertical cross-sectional view showing an example of a joint structure between a pile and a pillar according to the present invention. [Diagram 3] 3(a) and 3(b) are enlarged views showing a main part of an example of a joint structure between a pile and a pillar according to the present invention. [Figure 4] FIG. 4 is a vertical sectional view showing another example of the joint structure between a pile and a pillar of the present invention. [Diagram 5] FIG. 5 is a vertical sectional view showing still another example of the joint structure between a pile and a pillar of the present invention. [Figure 6]FIG. 6 is a vertical sectional view showing still another example of the joint structure between a pile and a pillar of the present invention. [Figure 7] FIG. 7 is a vertical sectional view showing still another example of the joint structure between a pile and a pillar of the present invention. [Figure 8] 8(a) and 8(b) are a plan view and a vertical sectional view showing the procedure of the construction method for the pile-column joint structure of the present invention. [Figure 9] 9(a) and 9(b) are a plan view and a vertical sectional view showing the procedure of the construction method for the pile-pillar joint structure of the present invention. [Figure 10] 10(a) and 10(b) are a plan view and a vertical sectional view showing the procedure of the construction method for the pile-column joint structure of the present invention. [Figure 11] 11(a) and 11(b) are a plan view and a vertical sectional view showing the procedure of the construction method for the pile-column joint structure of the present invention. [Figure 12] 12(a) and 12(b) are a plan view and a vertical sectional view showing the procedure of the construction method for the pile-column joint structure of the present invention. [Figure 13] 13(a) and 13(b) are a plan view and a vertical sectional view showing the procedure of the construction method for the pile-column joint structure of the present invention. [Figure 14] 14(a) and 14(b) are diagrams showing the stress transfer mechanism of the joint structure between a pile and a column of the present invention. [Figure 15] 15(a) and 15(b) are diagrams showing the stress transfer mechanism of the joint structure between a pile and a column of the present invention. [Figure 16] 16(a) and 16(b) are diagrams showing the stress transfer mechanism of the joint structure between a pile and a column of the present invention. [Figure 17] 17(a) to 17(c) are diagrams showing the stress transfer mechanism of the joint structure between a pile and a column of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, with reference to the drawings, an embodiment of the pile-pillar joint structure and its construction method of the present invention will be specifically described. <Pile and column joint structure> [First embodiment] Fig. 1 shows a perspective view of a building to which a joint structure between a pile and a column according to a first embodiment of the present invention is applied, and Fig. 2 shows a vertical cross-sectional view of the joint structure between a pile and a column according to the first embodiment.

[0015] As shown in Fig. 1, the pile-column joint structure of the first embodiment is used at a location where a steel column 2 of a low-rise steel-framed building is joined to a PHC pile (centrifugally formed prestressed high-strength concrete pile) 1 having a hollow cross section. As shown in Fig. 1, no foundation beam or footing is provided at the base of the steel column 2 of this steel-framed building, and the PHC pile 1 is directly joined to each base of the steel column 2.

[0016] Specifically, as shown in Fig. 2, a PHC pile 1 is erected in an excavated portion of ground G with its upper part protruding from the surface of the ground G. In the excavated portion of ground G, crushed stone 61 is laid around the PHC pile 1, and concrete 62 is poured in.

[0017] On the other hand, a base plate 21 and a shear key 23 having an outer dimension smaller than that of the steel column 2 are provided at the lower end of the steel column 2. The shear key 23 extends downward from the base plate 21 and is inserted into the upper end of the PHC pile 1 having a hollow cross section. From the viewpoint of ensuring its strength, the shear key 23 is preferably made of a seamless steel pipe, but it may be made of other steel pipes, shaped steel, etc.

[0018] 2, a support plate 24 is provided at the lower end of the shear key 23, protruding laterally from the shear key 23. In addition, a stiffener 26 is provided between the base plate 21 and the shear key 23 to stiffen the space between them, thereby increasing the strength and rigidity of the base plate 21.

[0019] As shown in Figure 2, the space from the upper end of the PHC pile 1 to the underside of the base plate 21 is filled with concrete 4 so as to cover the periphery of the shear key 23, thereby joining the PHC pile 1 and the steel column 2.

[0020] Furthermore, the pile-column joint structure of this embodiment includes an erection anchor frame 3 that is installed on the basing concrete 62 in the excavated portion of the ground G so as to surround the upper end of the PHC pile 1. The erection anchor frame 3 is fixed to the basing concrete 62 in the excavated portion of the ground G by post-installed anchors 33.

[0021] The construction anchor frame 3 is provided with anchor bolts 31 consisting of fully threaded bolts, and the base plate 21 is fastened to the anchor bolts 31 with nuts 32 to position the steel column 2 relative to the PHC pile 1. The construction anchor frame 3 is formed, for example, by combining angle irons with a cross-sectional size of L-100×100×13.

[0022] As shown in FIG. 3(a), a ring-shaped end plate provided at the upper end of the PHC pile 1 has a plurality of anti-slip plates (projections) 11 fixed by fillet welding at multiple locations in the circumferential direction so as to project inward from the inner surface of the PHC pile 1, while avoiding a pile hook member (not shown) provided at the end metal fitting. Alternatively, instead of the anti-slip plate 11, an end plate 12 (projection) provided at the upper end of the PHC pile 1 may be formed so as to project inward from the inner surface of the PHC pile 1, as shown in FIG. 3(b). Alternatively, instead of or in addition to the anti-slip plate 11 or the end plate 12, a horizontal rib (not shown) may be formed on the inner surface of the upper end of the PHC pile 1. By providing at least one of the anti-slip plate 11, the end plate 12, and the horizontal rib, a concrete strut is formed between the steel column 2 and the bearing plate 24 provided at the lower end of the shear key 23 when an axial tensile force acts on the PHC pile 1 from the steel column 2, as described later, resulting in a joint structure that can withstand a larger tensile force.

[0023] In this embodiment, the inner surface of the upper end of the PHC pile 1 may be roughened by ultra-high pressure cleaning or the like. In this way, when an axial tensile force acts from the steel column 2 to the PHC pile 1, the frictional resistance against pull-out is further increased.

[0024] A floor slab 7 may be provided around the base of the steel column 2, if necessary.

[0025] In this embodiment, the bearing plate 24, the slip stopper plate 11, the end plate 12, and the horizontal rib are not necessarily required, and may be omitted, for example, when the steel column 2 is provided at a location where a large pull-out force is not applied. By providing the bearing plate 24, the slip stopper plate 11, the end plate 12, and the horizontal rib as in this embodiment, when an axial tensile force acts from the steel column 2 to the PHC pile 1, as will be described later, a concrete strut is formed between the bearing plate 24 provided at the lower end of the shear key 23, resulting in a joint structure that can withstand a larger axial tensile force.

[0026] In addition, in this embodiment, the stiffener 26 is not necessarily required, but in order to adjust the joint form between the pile and the column to a semi-rigid joint, it is preferable to provide the stiffener 26 as in this embodiment as necessary to increase the strength and rigidity of the base plate 21. [Second embodiment] FIG. 4 shows a vertical cross-sectional view of a joint structure between a pile and a column according to a second embodiment of the present invention.

[0027] As shown in Fig. 4, in the joint structure between a pile and a column of this embodiment, the stiffener 26 in the joint structure between a pile and a column of the first embodiment is omitted. In other respects, the joint structure between a pile and a column of this embodiment is configured similarly to the joint structure between a pile and a column of the first embodiment.

[0028] In this embodiment, by omitting the stiffener 26 that stiffens the space between the base plate 21 and the shear key 23, the joint rigidity between the pile and the column can be adjusted to be low, and the bending moment transmitted to the joint from the upper steel column 2 can be reduced. In addition, by yielding the base plate 21 and causing bending deformation, sufficient plastic deformation capacity can be secured. [Third embodiment] FIG. 5 shows a vertical cross-sectional view of a joint structure between a pile and a column according to a third embodiment of the present invention.

[0029] As shown in FIG. 5, in the pile-to-column joint structure of this embodiment, in addition to the support plate 24 provided at the lower end of the shear key 23 in the pile-to-column joint structure of the second embodiment and protruding laterally, a support plate 25 protruding laterally from the shear key 23 is also provided at the middle part of the shear key 23.

[0030] In other respects, the joint structure between a pile and a column in this embodiment is configured similarly to the joint structure between a pile and a column in the second embodiment.

[0031] As in this embodiment, by providing support plates protruding laterally from the shear key 23 at multiple locations, a joint structure capable of withstanding even greater axial tensile force is obtained. [Fourth embodiment] FIG. 6 shows a vertical cross-sectional view of a joint structure between a pile and a column according to a fourth embodiment of the present invention.

[0032] As shown in Fig. 6, in the joint structure between a pile and a column of this embodiment, an engagement portion 22 that engages with concrete 4 is provided on the underside of the base plate 21 of the steel column 2 in the joint structure between a pile and a column of the second embodiment. For the engagement portion 22, for example, a flat bar having a size of about 25 x 32 x 450 can be used.

[0033] In other respects, the joint structure between a pile and a column in this embodiment is configured similarly to the joint structure between a pile and a column in the second embodiment.

[0034] In this embodiment, by providing an engagement portion 22 that engages with the concrete 4 on the underside of the base plate 21 of the steel column 2, as will be described later, when an axial tensile force or shear force acts from the steel column 2 to the PHC pile 1, a concrete strut is formed between the steel column 2 and the bearing plate 24 provided at the lower end of the shear key 23, resulting in a joint structure that can withstand larger axial tensile force and shear force. [Fifth embodiment] FIG. 7 shows a vertical cross-sectional view of a joint structure between a pile and a column according to a fifth embodiment of the present invention.

[0035] 7, in the joint structure between a pile and a pillar of this embodiment, a reinforcing band 13 is wound around the outer periphery of the upper end portion of the PHC pile 1 in the joint structure between a pile and a pillar of the fourth embodiment. The reinforcing band 13 can be formed by winding a steel plate, a steel wire, a wire made of carbon fiber, or the like, around the outer periphery of the upper end portion of the PHC pile 1.

[0036] In other respects, the joint structure between a pile and a column in this embodiment is configured similarly to the joint structure between a pile and a column in the fourth embodiment.

[0037] In this embodiment, a reinforcing band 13 is wrapped around the outer periphery of the upper end of the PHC pile 1, thereby increasing the resistance to loads acting horizontally on the inner surface of the upper end of the PHC pile 1, resulting in a joint structure that can withstand even greater shear forces.

[0038] In the pile-column joint structure of each of the above-mentioned embodiments, by changing the shape of each component, such as the thickness of the base plate 21, the size of the engagement portion 22, the diameter, thickness and insertion depth of the shear key 23 into the upper end of the PHC pile 1, the thickness, protruding width, number and arrangement of the support plates 24, 25, the thickness, number and arrangement of the stiffeners 26, the thickness, number and arrangement of the anti-slip plate 11, the thickness and protruding width of the end plate 12, and the strength of each of these components, the strength and rigidity of the pile-column joint structure, specifically, the compressive strength, tensile strength, bending strength, shear strength, compressive rigidity, tensile rigidity, bending rigidity and shear rigidity, can be adjusted to the desired magnitude.

[0039] By making such adjustments, for example, if the joint structure between a pile and a column is made semi-rigid, the bending force generated at the joint is reduced, making it possible to economically design the entire joint structure.

[0040] Furthermore, for example, when braces are provided between steel columns 2, a large axial tensile force is likely to act between the PHC pile 1 and the steel column 2, so it is preferable to set the thickness, etc. of the base plate 21 so that it can withstand this large axial tensile force. <Construction method for pile-column joint structure> A construction method for the joint structure between a pile and a pillar in each of the above-mentioned embodiments will be described with reference to Fig. 8 to Fig. 13. Hereinafter, the construction of the joint structure between a pile and a pillar in the second embodiment will be described.

[0041] First, as shown in the plan view of Fig. 8(a) and the vertical cross-sectional view of Fig. 8(b), the ground G is excavated and the PHC pile 1 is erected. At this time, the top of the PHC pile 1 is set to protrude from the surface of the ground G at the excavated portion.

[0042] Next, the soil inside the upper end of the PHC pile 1 (for example, a portion about 700 mm from the upper end of the PHC pile 1) is excavated and removed. Crushed stone 61 is laid in the excavated portion of the ground G so as to surround the periphery of the PHC pile 1, and basing concrete 62 is poured.

[0043] Next, as shown in the plan view of Figure 9(a) and the longitudinal section of Figure 9(b), anti-slip plates 11 are fixed by on-site fillet welding at multiple points around the circumference of the ring-shaped end plate provided at the upper end of the PHC pile 1 so that they protrude inward beyond the inner surface of the PHC pile 1, while avoiding the pile hanging member (not shown) provided on the end fitting.

[0044] Next, as shown in the plan view of Figure 10(a) and the longitudinal section of Figure 10(b), a construction anchor frame 3 is installed on the ground G so as to surround the upper end of the PHC pile 1 installed in the ground G, and is fixed to the waste concrete 62 in the excavated portion of the ground G by a post-installed anchor 33.

[0045] At this time, as shown in Figures 10(a) and 10(b), the construction anchor frame 3 may be installed so that the central axis of the construction anchor frame 3 is horizontally offset by a specified dimension (e.g., 80 mm) from the pile core of the PHC pile 1 depending on the design of the building, the conditions of the construction site, etc. At this time, the column core position on the basing concrete 62 is marked out, and the central axis of the construction anchor frame 3 is aligned with this marking and fixed to the basing concrete 62.

[0046] The construction anchor frame 3 is provided to temporarily support a section of the base of the steel column 2 in order to position the steel column 2 relative to the PHC pile 1.

[0047] Next, as shown in the plan view of Fig. 11(a) and the vertical cross section of Fig. 11(b), the steel column 2 is erected so that the shear key 23 of the steel column 2 is inserted into the upper end of the PHC pile 1 to a depth of, for example, about 500 mm from the top of the PHC pile 1. Then, the level of the PHC pile is adjusted, and the anchor bolt 31 of the erection anchor frame 3 is fastened with a nut 32 for temporary fixation.

[0048] Next, as shown in the plan view of Fig. 12(a) and the vertical cross section of Fig. 12(b), for example, a circular temporary formwork (temporary formwork) 5 is installed so as to surround the outer periphery of the upper end of the PHC pile 1. Furthermore, as shown in the plan view of Fig. 13(a) and the vertical cross section of Fig. 13(b), the space from the upper end of the PHC pile 1 to the underside of the base plate 21 of the steel column 2 is filled with concrete 4 so as to cover the periphery of the shear key 23 and is allowed to harden, thereby completing the construction of the joint structure between the pile and the column. Thereafter, if necessary, a floor slab 7 may be provided around the base of the steel column 2 as shown in Fig. 13(b).

[0049] A reusable formwork may be used instead of the circular disposable formwork 5, but using a disposable formwork can improve the safety and efficiency of the work. Also, the shape of the formwork is not necessarily limited to a circle, and it may be changed as appropriate as long as it can be installed so as to surround the outer periphery of the upper end of the PHC pile 1. <Stress transfer mechanism in pile-column joint structure> A stress transfer mechanism via the concrete 4 when an external force acts on the joint structure between a pile and a column in each of the above-mentioned embodiments will be described with reference to Figs. (When axial compression force is applied) In the longitudinal section of Figure 14(a) and the plan view of Figure 14(b), the area where concrete struts are formed in the concrete 4 when axial compressive force acts from the steel column 2 to the ring-shaped end plate provided at the upper end of the PHC pile 1 is shown shaded in gray.

[0050] As shown by the gray shading in Figure 14(a), a mechanical model can be assumed in which the above-mentioned concrete struts are formed directly above the end plate at the upper end of the PHC pile 1, and within a 45-degree range on both sides of this directly above the PHC pile 1 in the radial direction, and the compressive strength of the joint structure between the pile and the column can be evaluated. (When axial tension is applied) In the longitudinal section of Figure 15(a) and the plan view of Figure 15(b), the area where concrete struts are formed in the concrete 4 when an axial tensile force acts from the steel column 2 to the shear stop plate 11 at the upper end of the PHC pile 1 is shown shaded in gray.

[0051] As shown by the gray shading in Figure 15(a), the above-mentioned concrete struts are assumed to be formed directly above the protruding portion of the support plate 24 that protrudes laterally from the shear key 23 and in a range of 45 degrees radially outward from this portion, and directly below the portion of the shear stop plate 11 that protrudes inward from the inner surface of the PHC pile 1 and in a range of 45 degrees radially inward from this portion, and a mechanical model can be used to evaluate the tensile strength of the joint structure between the pile and the column. (When shear force is applied) In the longitudinal section of Figure 16(a) and the plan view of Figure 16(b), the area where concrete struts are formed in the concrete 4 when a shear force acts between the steel column 2 and the PHC pile 1, is shown shaded in grey. The concrete struts transmit compressive force from the engagement portion 22 provided on the underside of the base plate 21 of the steel column 2 to the inner surface of the upper end of the PHC pile 1.

[0052] As shown by the gray shading in Figure 16(a), a mechanical model can be assumed in which the above-mentioned concrete struts are formed on the horizontal side of the engagement part 22 provided on the underside of the base plate 21 of the steel column 2 and in a range of 45 degrees diagonally downward from this side, and on the horizontal side of the inner surface of the upper end of the PHC pile 1 and in a range of 45 degrees diagonally upward from this side, and the shear strength of the joint structure between the pile and the column can be evaluated. This mechanical model is based on the contents of Non-Patent Document 1. (When bending force and axial force act simultaneously) In the longitudinal cross-sectional views of Figures 17(a) to 17(c), the area where concrete struts that transmit compressive force are formed in the concrete 4 when bending force and axial force act simultaneously between the steel column 2 and the PHC pile 1 is shown shaded in gray. Figures 17(a) to 17(c) show the cases when the bending force is relatively small, medium, and relatively large, respectively.

[0053] When the bending force is relatively small, a concrete strut is formed in the concrete 4, transmitting the compressive force from the entire underside of the base plate 21 of the steel column 2 to one side of the upper end of the PHC pile 1, as shown in Figure 17(a).

[0054] When the bending force is medium, as shown in Fig. 17(b), concrete struts are formed in the concrete 4, which transmit compressive force from a part of one side of the underside of the base plate 21 of the steel column 2 to one side of the upper end of the PHC pile 1. In the case shown in Fig. 17(b), the area in which the concrete struts are formed in the concrete 4 is more limited than in the case shown in Fig. 17(a).

[0055] When the bending force is relatively large, as shown in Figure 17(c), a concrete strut is formed in the concrete 4 which transmits compressive force from a local area (very small part) on one side of the underside of the base plate 21 of the steel column 2 to one side of the upper end of the PHC pile 1. In the case shown in Figure 17(c), an axial tensile force (pulling force) acts on the PHC pile 1 from the position of the shear key 23 of the steel column 2.

[0056] In this case, the shear key 23 corresponds to one anchor bolt, and a mechanical model similar to that of the exposed column base can be assumed. A concrete strut similar to that shown in Figure 15(a) is further formed between the shear key 23 and the PHC pile 1.

[0057] In addition, by evaluating the out-of-plane bending deformation of the base plate 21, assuming that the joint between the base plate 21 and the shear key 23 is equivalent to a unequal width joint, the bending rigidity of the joint between the steel column 2 and the shear key 23 can be evaluated.

[0058] By assuming such a mechanical model, it is possible to evaluate the bending strength of the joint structure between a pile and a column.

[0059] According to the pile-to-column joint structure of each of the above-mentioned embodiments, since footings and foundation beams are not required, the amount of excavated soil and the amount of steel used can be reduced, thereby simplifying the structure and reducing costs. In addition, by using a semi-rigid joint, the bending force generated at the joint can be reduced, thereby improving rationality and economy.

[0060] In each of the above embodiments, the joint structure between the PHC pile 1 and the steel column 2 has been described; however, the joint structure between the pile and column of the present invention is not limited to this, and can also be applied to, for example, the joint structure between various prefabricated piles having a hollow cross section, such as PRC piles (centrifugally formed prestressed reinforced high-strength concrete piles), SC piles (centrifugally formed concrete piles with steel pipes), and steel pipe piles, and various columns having a base plate at their lower end.

[0061] In addition, in each of the above embodiments, an example has been described in which the foundation beam of the building is omitted, but the present invention can also be applied in the same manner in the case where a foundation beam made of steel is provided to connect the bases of the steel columns. [Explanation of symbols]

[0062] 1 PHC pile (pile) 11 Anti-slip plate (protruding part) 12 End plate (protrusion) 13 Reinforcement band 2 Steel columns (pillars) 21 Base plate 22 Engagement part 23 Siaqi 24, 25 Bearing plate 26 Stiffener 3 Anchor Frame 31 Anchor bolt 32 Nut 33 Post-installed anchor 4. Concrete 5 Circular throw-away formwork (throw-away formwork) 61 Crushed Stone 62 Waste concrete 7 Floor slab G. Ground

Claims

1. A joint structure between a pile and a column having a hollow cross section, A base plate and a shear key having an outer dimension smaller than that of the column are provided at the lower end of the column and extending downward from the base plate and inserted into the upper end of the pile. The space from the upper end of the pile to the lower surface of the base plate is filled with concrete so as to cover the periphery of the shear key, Further provided is an anchor frame installed so as to surround the upper end of the pile in the excavated portion of the ground into which the pile is to be erected; A joint structure between a pile and a column, in which the column is positioned relative to the pile by fastening the base plate to an anchor bolt provided on the anchor frame.

2. The shear key is provided with a support plate protruding laterally, 2. The joint structure between a pile and a column according to claim 1, wherein an upper end of the pile is provided with a protrusion that protrudes inward beyond the inner surface of the pile.

3. The pile-column joint structure according to claim 2 , wherein the protrusion comprises a stopper plate fixed to a plurality of points in the circumferential direction of the upper end of the pile.

4. The pile-column joint structure according to claim 2 , wherein the protrusion comprises an end plate provided at the upper end of the pile.

5. The pile-column joint structure according to any one of claims 1 to 4, wherein a stiffener is provided between the base plate and the shear key.

6. The pile-column joint structure according to any one of claims 1 to 5, wherein an engagement portion is provided on the underside of the base plate for engaging with the concrete.

7. A construction method for the pile-column joint structure according to claim 1, The anchor frame is installed so as to surround the upper end of the pile in the excavated portion of the ground where the pile is to be erected, The pillar is erected so that the shear key of the pillar is inserted into the upper end of the pile, The base plate is fastened to an anchor bolt provided in the anchor frame to position the column relative to the pile; A formwork is installed so as to surround the outer periphery of the upper end of the pile, and concrete is filled in the space from the upper end of the pile to the lower surface of the base plate so as to cover the periphery of the shear key. A construction method for a joint structure between a pile and a column.

8. The construction method for a pile-to-column joint structure according to claim 7, wherein the formwork is a disposable formwork.

Images