CA2920289A1 - Composite structure - Google Patents
Composite structure Download PDFInfo
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- CA2920289A1 CA2920289A1 CA2920289A CA2920289A CA2920289A1 CA 2920289 A1 CA2920289 A1 CA 2920289A1 CA 2920289 A CA2920289 A CA 2920289A CA 2920289 A CA2920289 A CA 2920289A CA 2920289 A1 CA2920289 A1 CA 2920289A1
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- Prior art keywords
- steel pipe
- protrusion
- region
- pipe pile
- protrusions
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/24—Prefabricated piles
- E02D5/30—Prefabricated piles made of concrete or reinforced concrete or made of steel and concrete
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- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Piles And Underground Anchors (AREA)
- Foundations (AREA)
Abstract
A composite structure of the present invention includes: a steel pipe; a joint object member having an end portion inserted into the steel pipe; and concrete which fills a space between an inner circumferential surface of the steel pipe and the end portion of the joint object member. The steel pipe includes protrusions which protrude inward in a radial direction of the steel pipe from the inner circumferential surface of the steel pipe and extend in a spiral shape along a pipe axis direction of the steel pipe.
The protrusions extend in the spiral shape along the pipe axis direction to straddle a boundary between a stiffening region and a raw pipe region in the steel pipe. An extension length of the protrusion in the pipe axis direction in the raw pipe region is equal to or greater than a local buckling half-wavelength of the steel pipe.
The protrusions extend in the spiral shape along the pipe axis direction to straddle a boundary between a stiffening region and a raw pipe region in the steel pipe. An extension length of the protrusion in the pipe axis direction in the raw pipe region is equal to or greater than a local buckling half-wavelength of the steel pipe.
Description
COMPOSITE STRUCTURE
[Technical Field of the Invention]
[0001]
The present invention relates to a composite structure which can be applied to a joint of a steel pipe and a joint object member.
Priority is claimed on Japanese Patent Application No. 2013-.197688, filed on September 25, 2013, the content of which is incorporated herein by reference.
[Related Art]
[Technical Field of the Invention]
[0001]
The present invention relates to a composite structure which can be applied to a joint of a steel pipe and a joint object member.
Priority is claimed on Japanese Patent Application No. 2013-.197688, filed on September 25, 2013, the content of which is incorporated herein by reference.
[Related Art]
[0002]
Hitherto, in order to enhance the bond strength between a steel pipe pile and concrete, a technology in which, protrusions are provided on at least one of the inner circumferential surface and the outer circumferential surface of the front end section of the steel pipe pile to prevent slippage between the steel pipe pile and the concrete, is generally known.
Hitherto, in order to enhance the bond strength between a steel pipe pile and concrete, a technology in which, protrusions are provided on at least one of the inner circumferential surface and the outer circumferential surface of the front end section of the steel pipe pile to prevent slippage between the steel pipe pile and the concrete, is generally known.
[0003]
In Patent Document 1 mentioned below, in order to enhance the bond strength between the steek surface and the concrete, a technology in which, annular protrusions are provided on the inner circumferential surface of the steel pipe pile along the circumferential direction of the steel pipe pile to prevent slippage between the steel pipe pile and the concrete, is disclosed.
In Patent Document 1 mentioned below, in order to enhance the bond strength between the steek surface and the concrete, a technology in which, annular protrusions are provided on the inner circumferential surface of the steel pipe pile along the circumferential direction of the steel pipe pile to prevent slippage between the steel pipe pile and the concrete, is disclosed.
[0004]
In Patent Documents 2 and 3 mentioned below, in order to enhance the bond strength between the steek surface and the concrete, a technology in which, spiral protrusions are provided on the inner circumferential surface or the outer circumferential surface of the steel pipe pile to prevent slippage between the steel pipe pile and the concrete, is disclosed.
In Patent Documents 2 and 3 mentioned below, in order to enhance the bond strength between the steek surface and the concrete, a technology in which, spiral protrusions are provided on the inner circumferential surface or the outer circumferential surface of the steel pipe pile to prevent slippage between the steel pipe pile and the concrete, is disclosed.
[0005]
In Non-Patent Document 1 mentioned below, as a method of manufacturing a steel pipe pile having spiral protrusions provided on the inner circumferential surface or the outer circumferential surface, a method of manufacturing a steel pipe pile having spiral protrusions by cold forming a steel strip provided with protrusions in a spiral form is disclosed. In Non-Patent Document 1, the bond strength between the steel pipe pile and concrete is decreased as an angle in a direction of the spiral protrusions increases.
Therefore, in order to ensure the enough bond strength between the steel pipe pile and the concrete, the angle in the direction of the spiral protrusions is limited to 40 or lower.
In Non-Patent Document 1 mentioned below, as a method of manufacturing a steel pipe pile having spiral protrusions provided on the inner circumferential surface or the outer circumferential surface, a method of manufacturing a steel pipe pile having spiral protrusions by cold forming a steel strip provided with protrusions in a spiral form is disclosed. In Non-Patent Document 1, the bond strength between the steel pipe pile and concrete is decreased as an angle in a direction of the spiral protrusions increases.
Therefore, in order to ensure the enough bond strength between the steel pipe pile and the concrete, the angle in the direction of the spiral protrusions is limited to 40 or lower.
[0006]
In Non-Patent Document 2 mentioned below, the results of experiments conducted to examine the bond strength between a steel pipe having spiral protrusions provided on the inner circumferential surface, and concrete are disclosed. The results of the experiments show that even when an angle in a direction of the spiral protrusions is 45 , necessary bond strength between the steel pipe and the concrete can be ensured.
[Prior Art Document]
[Patent Document]
In Non-Patent Document 2 mentioned below, the results of experiments conducted to examine the bond strength between a steel pipe having spiral protrusions provided on the inner circumferential surface, and concrete are disclosed. The results of the experiments show that even when an angle in a direction of the spiral protrusions is 45 , necessary bond strength between the steel pipe and the concrete can be ensured.
[Prior Art Document]
[Patent Document]
[0007]
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2007-51500;
[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2007-32044;
[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. H8-284159.
[Non-Patent Document]
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2007-51500;
[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2007-32044;
[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. H8-284159.
[Non-Patent Document]
[0008]
[Non-Patent Document 1] JIS A 5525 "Steel pipe piles";
[Non-Patent Document 2] "ADHESION PROPERTIES OF LAP JOINT DUE
TO STEEL PIPE WITH RIBS", Proceedings of Annual Conference of the Japan Society of Civil Engineers, 5, Vol. 50, pages 880 and 881, 1995.
[Disclosure of the Invention]
[Problems to be Solved by the Invention]
[Non-Patent Document 1] JIS A 5525 "Steel pipe piles";
[Non-Patent Document 2] "ADHESION PROPERTIES OF LAP JOINT DUE
TO STEEL PIPE WITH RIBS", Proceedings of Annual Conference of the Japan Society of Civil Engineers, 5, Vol. 50, pages 880 and 881, 1995.
[Disclosure of the Invention]
[Problems to be Solved by the Invention]
[0009]
However, in the steel pipe piles disclosed in Patent Documents 1, 2, and 3, the stiffness and the strength of a stiffening region (a region in which the concrete comes into contact with the inner circumferential surface of the steel pipe pile) are significantly different from those of a raw pipe region (a region in which the concrete does not come into contact with the inner circumferential surface of the steel pipe pile).
Particularly, in the boundary between the stiffening region and the raw pipe region of the steel pipe pile, the stiffness and strength of the steel pipe pile are significantly decreased.
However, in the steel pipe piles disclosed in Patent Documents 1, 2, and 3, the stiffness and the strength of a stiffening region (a region in which the concrete comes into contact with the inner circumferential surface of the steel pipe pile) are significantly different from those of a raw pipe region (a region in which the concrete does not come into contact with the inner circumferential surface of the steel pipe pile).
Particularly, in the boundary between the stiffening region and the raw pipe region of the steel pipe pile, the stiffness and strength of the steel pipe pile are significantly decreased.
[0010]
Therefore, in the steel pipe piles disclosed in Patent Documents 1, 2, and 3, when an external force such as a bending force, axial force, and/or shear force is loaded on the steel pipe pile, stress concentration caused by the external force occurs near the boundary between the stiffening region and the raw pipe region of the steel pipe pile, and thus there is a possibility that local buckling may occur in the raw pipe region.
Therefore, in the steel pipe piles disclosed in Patent Documents 1, 2, and 3, when an external force such as a bending force, axial force, and/or shear force is loaded on the steel pipe pile, stress concentration caused by the external force occurs near the boundary between the stiffening region and the raw pipe region of the steel pipe pile, and thus there is a possibility that local buckling may occur in the raw pipe region.
[0011]
In addition, as described above, when the local buckling occurs in the raw pipe region of the steel pipe pile, there is a possibility that, at a junction of an upper column of a building structure or the like and the steel pipe pile, the building structure may not be insufficiently supported.
In addition, as described above, when the local buckling occurs in the raw pipe region of the steel pipe pile, there is a possibility that, at a junction of an upper column of a building structure or the like and the steel pipe pile, the building structure may not be insufficiently supported.
[0012]
As one of the methods to prevent local buckling in the raw pipe region of the steel pipe pile, a method of increasing the plate thickness of the steel pipe pile is considered. However, when the method of increasing the plate thickness of the steel pipe pile is employed, the weight of the steel pipe pile is increased, and the material cost is also increased. Therefore, this method is not reasonable. In addition, as another method to prevent local buckling in the raw pipe region of the steel pipe pile, installing a stiffening material such as stiffener on the raw pipe region may be considered. However, this results in an increase in processing time and effort.
As one of the methods to prevent local buckling in the raw pipe region of the steel pipe pile, a method of increasing the plate thickness of the steel pipe pile is considered. However, when the method of increasing the plate thickness of the steel pipe pile is employed, the weight of the steel pipe pile is increased, and the material cost is also increased. Therefore, this method is not reasonable. In addition, as another method to prevent local buckling in the raw pipe region of the steel pipe pile, installing a stiffening material such as stiffener on the raw pipe region may be considered. However, this results in an increase in processing time and effort.
[0013]
The present invention has been made taking the foregoing circumstances into consideration, and an object thereof is to provide a composite structure capable of realizing the enhancement of local buckling resistance in the boundary between a stiffening region and a raw pipe region of a steel pipe without increasing the plate thickness of the steel pipe and using a stiffening material such as stiffener.
[Measures for Solving the Problem]
The present invention has been made taking the foregoing circumstances into consideration, and an object thereof is to provide a composite structure capable of realizing the enhancement of local buckling resistance in the boundary between a stiffening region and a raw pipe region of a steel pipe without increasing the plate thickness of the steel pipe and using a stiffening material such as stiffener.
[Measures for Solving the Problem]
[0014]
In order to accomplish the object to solve the problems, the present invention employs the following measures.
(1) A composite structure according to an aspect of the present invention includes: a steel pipe; a joint object member having an end portion inserted into the steel pipe; and concrete which fills a space between an inner circumferential surface of the steel pipe and the end portion of the joint object member. The steel pipe includes protrusions which protrude inward in a radial direction of the steel pipe from the inner circumferential surface of the steel pipe and extend in a spiral shape along a pipe axis direction of the steel pipe. When a region in which the concrete comes into contact with the inner circumferential surface of the steel pipe is defined as a stiffening region and a region in which the concrete does not come into contact with the inner circumferential surface of the steel pipe is defined as a raw pipe region, the protrusions extend in the spiral shape along the pipe axis direction to straddle a boundary between the stiffening region and the raw pipe region. An extension length of the protrusion in the pipe axis direction in the raw pipe region is equal to or greater than a local buckling half-wavelength of the steel pipe. When the local buckling half-wavelength of the steel pipe is defined as A, (mm), an outer diameter of the steel pipe is defined as D
(mm), and a plate thickness of the steel pipe is defined as t (mm), the local buckling half-wavelength ?\., is expressed in the following Expression (1), and a ratio D/t obtained by dividing the outer diameter D by the plate thickness t of the steel pipe is 50 or higher and 100 or lower.
In order to accomplish the object to solve the problems, the present invention employs the following measures.
(1) A composite structure according to an aspect of the present invention includes: a steel pipe; a joint object member having an end portion inserted into the steel pipe; and concrete which fills a space between an inner circumferential surface of the steel pipe and the end portion of the joint object member. The steel pipe includes protrusions which protrude inward in a radial direction of the steel pipe from the inner circumferential surface of the steel pipe and extend in a spiral shape along a pipe axis direction of the steel pipe. When a region in which the concrete comes into contact with the inner circumferential surface of the steel pipe is defined as a stiffening region and a region in which the concrete does not come into contact with the inner circumferential surface of the steel pipe is defined as a raw pipe region, the protrusions extend in the spiral shape along the pipe axis direction to straddle a boundary between the stiffening region and the raw pipe region. An extension length of the protrusion in the pipe axis direction in the raw pipe region is equal to or greater than a local buckling half-wavelength of the steel pipe. When the local buckling half-wavelength of the steel pipe is defined as A, (mm), an outer diameter of the steel pipe is defined as D
(mm), and a plate thickness of the steel pipe is defined as t (mm), the local buckling half-wavelength ?\., is expressed in the following Expression (1), and a ratio D/t obtained by dividing the outer diameter D by the plate thickness t of the steel pipe is 50 or higher and 100 or lower.
[0015]
2 = K (D = t) = = - ( i ) (where, K is a dimensionless constant)
2 = K (D = t) = = - ( i ) (where, K is a dimensionless constant)
[0016]
(2) In the composite structure described in (1), when the protrusion is viewed from the inside in the radial direction of the steel pipe, an angle between a circumferential direction of the steel pipe and the protrusion may be 30 or higher and lower than 90 .
(2) In the composite structure described in (1), when the protrusion is viewed from the inside in the radial direction of the steel pipe, an angle between a circumferential direction of the steel pipe and the protrusion may be 30 or higher and lower than 90 .
[0017]
(3) In the composite structure described in (1) or (2), when the steel pipe is viewed in a section parallel to the pipe axis direction, convex sections of the protrusions may be arranged with an interval equal to or smaller than the local buckling half-wavelength A, therebetween along the pipe axis direction.
[Effects of the Invention]
(3) In the composite structure described in (1) or (2), when the steel pipe is viewed in a section parallel to the pipe axis direction, convex sections of the protrusions may be arranged with an interval equal to or smaller than the local buckling half-wavelength A, therebetween along the pipe axis direction.
[Effects of the Invention]
[0018]
According to the composite structure described in (1), the difference in the stiffness and the strength of this structure between the stiffening region and the raw pipe region of the steel pipe is reduced in the boundary between the stiffening region and the raw pipe region of the steel pipe, and thus the stiffness and the strength of the steel pipe are gradually decreased from the stiffening region to the raw pipe region.
Therefore, it is possible to prevent rapid decreases in the stiffness and the strength of the steel pipe.
According to the composite structure described in (1), the difference in the stiffness and the strength of this structure between the stiffening region and the raw pipe region of the steel pipe is reduced in the boundary between the stiffening region and the raw pipe region of the steel pipe, and thus the stiffness and the strength of the steel pipe are gradually decreased from the stiffening region to the raw pipe region.
Therefore, it is possible to prevent rapid decreases in the stiffness and the strength of the steel pipe.
[0019]
According to the composite structure described in (1), in the boundary between the stiffening region and the raw pipe region of the steel pipe, rapid decreases in the stiffness and strength of the steel pipe are prevented, and thus the occurrence of stress concentration on the steel pipe caused by an external force such as a bending force, axial force, and/or shear force is prevented. Therefore, it is possible to prevent the occurrence of local buckling in the raw pipe region.
According to the composite structure described in (1), in the boundary between the stiffening region and the raw pipe region of the steel pipe, rapid decreases in the stiffness and strength of the steel pipe are prevented, and thus the occurrence of stress concentration on the steel pipe caused by an external force such as a bending force, axial force, and/or shear force is prevented. Therefore, it is possible to prevent the occurrence of local buckling in the raw pipe region.
[0020]
According to the composite structure described in (1), the local buckling resistance of the steel pipe in the boundary between the stiffening region and the raw pipe region of the steel pipe can be enhanced, and thus it is possible to sufficiently support a building structure or the like at a junction of the steel pipe and the joint object member.
According to the composite structure described in (1), the local buckling resistance of the steel pipe in the boundary between the stiffening region and the raw pipe region of the steel pipe can be enhanced, and thus it is possible to sufficiently support a building structure or the like at a junction of the steel pipe and the joint object member.
[0021]
According to the composite structure described in (2), a thin section of the steel pipe in which the protrusion is not present is not continuous in a section of the steel pipe in the pipe circumferential direction thereof As a result, the local buckling resistance of the steel pipe can be enhanced, and thus it is possible to prevent the occurrence of the local buckling in the raw pipe region.
According to the composite structure described in (2), a thin section of the steel pipe in which the protrusion is not present is not continuous in a section of the steel pipe in the pipe circumferential direction thereof As a result, the local buckling resistance of the steel pipe can be enhanced, and thus it is possible to prevent the occurrence of the local buckling in the raw pipe region.
[0022]
In addition, according to the composite structure described in (2), it is possible to reliably prevent the occurrence of local buckling in which the pipe wall is crushed into a bellows shape in the steel pipe. In addition, the concrete is reliably adhered to the inner circumferential surface of the steel pipe, and thus it is possible to sufficiently ensure the bond strength between the steel pipe and the concrete.
In addition, according to the composite structure described in (2), it is possible to reliably prevent the occurrence of local buckling in which the pipe wall is crushed into a bellows shape in the steel pipe. In addition, the concrete is reliably adhered to the inner circumferential surface of the steel pipe, and thus it is possible to sufficiently ensure the bond strength between the steel pipe and the concrete.
[0023]
According to the composite structure described in (2), the protrusions provided in the stiffening region to enhance the bond strength between the steel pipe and the concrete can be extended along the pipe axis direction of the steel pipe.
Therefore, it is possible to efficiently manufacture a steel pipe having enhanced local buckling resistance.
According to the composite structure described in (2), the protrusions provided in the stiffening region to enhance the bond strength between the steel pipe and the concrete can be extended along the pipe axis direction of the steel pipe.
Therefore, it is possible to efficiently manufacture a steel pipe having enhanced local buckling resistance.
[0024]
Particularly, in the related art, in a case where protrusions are provided in a steel pipe only for the purpose of ensuring the bond strength between the steel pipe and concrete, the protrusions are inclined at about 10 to 20 with respect to the circumferential direction of the steel pipe. However, according to the composite structure described in (2), a manufacturing process of a steel pipe provided with protrusions is directly used to ensure the bond strength between the steel pipe and concrete, and the protrusions are inclined at an angle of 300 or higher with respect to the circumferential direction of the steel pipe, thereby efficiently providing the protrusions that enhance the local buckling resistance of the steel pipe.
Particularly, in the related art, in a case where protrusions are provided in a steel pipe only for the purpose of ensuring the bond strength between the steel pipe and concrete, the protrusions are inclined at about 10 to 20 with respect to the circumferential direction of the steel pipe. However, according to the composite structure described in (2), a manufacturing process of a steel pipe provided with protrusions is directly used to ensure the bond strength between the steel pipe and concrete, and the protrusions are inclined at an angle of 300 or higher with respect to the circumferential direction of the steel pipe, thereby efficiently providing the protrusions that enhance the local buckling resistance of the steel pipe.
[0025]
According to the composite structure described in (3), it is possible to prevent the occurrence of local buckling in the raw pipe region due to an external force loaded on the steel pipe between the protrusions which are adjacent to each other along the pipe axis direction of the steel pipe.
[Brief Description of the Drawings]
According to the composite structure described in (3), it is possible to prevent the occurrence of local buckling in the raw pipe region due to an external force loaded on the steel pipe between the protrusions which are adjacent to each other along the pipe axis direction of the steel pipe.
[Brief Description of the Drawings]
[0026]
FIG. 1 is a longitudinal sectional view showing a composite structure 1 according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a region C enclosed by dotted lines in FIG. 1.
FIG. 3 is an enlarged view of a region including the boundary between a stiffening region B1 and a raw pipe region B2 in FIG. 1.
FIG. 4 is a view schematically showing each of a case where shear force Q is exerted on a steel pipe pile 10 and a case where axial force N is loaded on the steel pipe pile 10.
FIG. 5 shows a graph in which "L/(D0" in Table 1 is set as the horizontal axis, and "Qmax/Q0" in Table 1 is set as the vertical axis.
FIG. 6 showg a graph in which a protrusion inclination angle O in Table 2 is set as the horizontal axis, and "Qmax/Q0" in Table 2 is set as the vertical axis.
FIG. 7 shows a graph in which the protrusion inclination angle 0 in Table 3 is set as the horizontal axis, and "1\1i-flax/N0" in Table 3 is set as the vertical axis.
FIG. 8 shows a graph in which "S/(D0" in Table 4 is set as the horizontal axis, and "Qmax/QO" in Table 4 is set as the vertical axis.
FIG. 9 is a view showing a modification example of the embodiment.
FIG. 10 is a view showing a modification example of the embodiment.
[Embodiments of the Invention]
FIG. 1 is a longitudinal sectional view showing a composite structure 1 according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a region C enclosed by dotted lines in FIG. 1.
FIG. 3 is an enlarged view of a region including the boundary between a stiffening region B1 and a raw pipe region B2 in FIG. 1.
FIG. 4 is a view schematically showing each of a case where shear force Q is exerted on a steel pipe pile 10 and a case where axial force N is loaded on the steel pipe pile 10.
FIG. 5 shows a graph in which "L/(D0" in Table 1 is set as the horizontal axis, and "Qmax/Q0" in Table 1 is set as the vertical axis.
FIG. 6 showg a graph in which a protrusion inclination angle O in Table 2 is set as the horizontal axis, and "Qmax/Q0" in Table 2 is set as the vertical axis.
FIG. 7 shows a graph in which the protrusion inclination angle 0 in Table 3 is set as the horizontal axis, and "1\1i-flax/N0" in Table 3 is set as the vertical axis.
FIG. 8 shows a graph in which "S/(D0" in Table 4 is set as the horizontal axis, and "Qmax/QO" in Table 4 is set as the vertical axis.
FIG. 9 is a view showing a modification example of the embodiment.
FIG. 10 is a view showing a modification example of the embodiment.
[Embodiments of the Invention]
[0027]
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a composite structure 1 according to the embodiment of the present invention. As shown in FIG. 1, the composite structure 1 according to this embodiment includes a steel pipe pile 10 (steel pipe) which is driven into the ground, H-shaped steel 20 (joint object member) having an end portion inserted into the steel pipe pile 10, and concrete 30 which fills a space between an inner circumferential surface 11 of the steel pipe pile 10 and the end portion of the H-shaped steel 20 (the portion inserted into the steel pipe pile 10).
In addition, FIG. 1 is a view of the steel pipe pile 10 viewed in a section parallel to a pipe axis direction (Y direction in FIG. 1) of the steel pipe pile 10.
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a composite structure 1 according to the embodiment of the present invention. As shown in FIG. 1, the composite structure 1 according to this embodiment includes a steel pipe pile 10 (steel pipe) which is driven into the ground, H-shaped steel 20 (joint object member) having an end portion inserted into the steel pipe pile 10, and concrete 30 which fills a space between an inner circumferential surface 11 of the steel pipe pile 10 and the end portion of the H-shaped steel 20 (the portion inserted into the steel pipe pile 10).
In addition, FIG. 1 is a view of the steel pipe pile 10 viewed in a section parallel to a pipe axis direction (Y direction in FIG. 1) of the steel pipe pile 10.
[0028]
The H-shaped steel 20 is, for example, a column member of a building structure (upper structure). In a state where the end portion of the H-shaped steel 20 is inserted into the steel pipe pile 10 that is driven into the ground as the foundation structure, the concrete 30 fills the space between the inner circumferential surface 11 of the steel pipe pile 10 and the end portion of the H-shaped steel 20 such that the steel pipe pile 10 and the H-shaped steel 20 are joined together. As showned in FIG. 1, in order to increase the joining strength between the steel pipe pile 10 and the H-shaped steel 20, it is preferable that a baseplate 21 is joined to a tip of the H-shaped steel 20.
However, the baseplate 21 is not essential.
The H-shaped steel 20 is, for example, a column member of a building structure (upper structure). In a state where the end portion of the H-shaped steel 20 is inserted into the steel pipe pile 10 that is driven into the ground as the foundation structure, the concrete 30 fills the space between the inner circumferential surface 11 of the steel pipe pile 10 and the end portion of the H-shaped steel 20 such that the steel pipe pile 10 and the H-shaped steel 20 are joined together. As showned in FIG. 1, in order to increase the joining strength between the steel pipe pile 10 and the H-shaped steel 20, it is preferable that a baseplate 21 is joined to a tip of the H-shaped steel 20.
However, the baseplate 21 is not essential.
[0029]
The steel pipe pile 10 is, for example, a steel pipe having an outer diameter D of 1000 mm, a plate thickness t of 6.6 mm, and a Poisson's ratio v of 0.28 to 0.30. The outer diameter D, the plate thickness t, and the Poisson's ratio v of the steel pipe pile 10 are not limited to the above-mentioned numeral values. However, when the plate thickness t of the steel pipe pile 10 is too high, there is an advantage in that the local buckling resistance of the steel pipe pile 10 is increased, while there is a disadvantage in that the weight and material cost of the steel pipe pile 10 is increased.
Therefore, in this embodiment, in consideration of a balance between the advantage and the disadvantage caused by the plate thickness t, the ratio D/t obtained by dividing the outer diameter D by the plate thickness t is set to be 50 or higher and 100 or lower.
In a case where a steel material for construction is used as the steel pipe pile 10 and the ratio D/t obtained by dividing the outer diameter D by the plate thickness t becomes less than 50, the strength of the steel pipe pile 10 is reduced due to local buckling. Therefore, it is preferable that the lower limit of the ratio D/t is set to 50.
On the other hand, there is no particular limitation regarding the upper limit of the ratio D/t. However, the upper limit of the ratio D/t of a steel pipe which is manufactured for construction and is distributed to the market is generally 100. Accordingly, in this embodiment, the upper limit of the ratio D/t of the steel pipe pile 10 is also set to 100.
The steel pipe pile 10 includes protrusions 12 which protrude inward in a radial direction of the steel pipe pile 10 (X direction in FIG. 1) from the inner circumferential surface 11 of the steel pipe pile 10 and extend in a spiral shape along the pipe axis direction Y of the steel pipe pile 10.
The steel pipe pile 10 is, for example, a steel pipe having an outer diameter D of 1000 mm, a plate thickness t of 6.6 mm, and a Poisson's ratio v of 0.28 to 0.30. The outer diameter D, the plate thickness t, and the Poisson's ratio v of the steel pipe pile 10 are not limited to the above-mentioned numeral values. However, when the plate thickness t of the steel pipe pile 10 is too high, there is an advantage in that the local buckling resistance of the steel pipe pile 10 is increased, while there is a disadvantage in that the weight and material cost of the steel pipe pile 10 is increased.
Therefore, in this embodiment, in consideration of a balance between the advantage and the disadvantage caused by the plate thickness t, the ratio D/t obtained by dividing the outer diameter D by the plate thickness t is set to be 50 or higher and 100 or lower.
In a case where a steel material for construction is used as the steel pipe pile 10 and the ratio D/t obtained by dividing the outer diameter D by the plate thickness t becomes less than 50, the strength of the steel pipe pile 10 is reduced due to local buckling. Therefore, it is preferable that the lower limit of the ratio D/t is set to 50.
On the other hand, there is no particular limitation regarding the upper limit of the ratio D/t. However, the upper limit of the ratio D/t of a steel pipe which is manufactured for construction and is distributed to the market is generally 100. Accordingly, in this embodiment, the upper limit of the ratio D/t of the steel pipe pile 10 is also set to 100.
The steel pipe pile 10 includes protrusions 12 which protrude inward in a radial direction of the steel pipe pile 10 (X direction in FIG. 1) from the inner circumferential surface 11 of the steel pipe pile 10 and extend in a spiral shape along the pipe axis direction Y of the steel pipe pile 10.
[0030]
FIG. 2 is an enlarged view of a region C enclosed by dotted lines in FIG. 1.
As shown in FIG. 2, the length of a convex section of the protrusion 12 in the pipe axis direction Y of the steel pipe pile 10 is defined as a protrusion width w. In addition, the length of the convex section of the protrusion 12 in the radial direction X of the steel pipe pile 10 is defined as a protrusion height h. In addition, the distance between the centers of the convex sections of the protrusions 12 which are adjacent to each other along the pipe axis direction Y is defined as a protrusion interval S. Furthermore, when the protrusion 12 is viewed from the inside in the radial direction X of the steel pipe pile 10, an angle between a circumferential direction (W direction in FIG. 2) of the steel pipe pile 10 and the protrusion 12 is defined as a protrusion inclination angle O.
FIG. 2 is an enlarged view of a region C enclosed by dotted lines in FIG. 1.
As shown in FIG. 2, the length of a convex section of the protrusion 12 in the pipe axis direction Y of the steel pipe pile 10 is defined as a protrusion width w. In addition, the length of the convex section of the protrusion 12 in the radial direction X of the steel pipe pile 10 is defined as a protrusion height h. In addition, the distance between the centers of the convex sections of the protrusions 12 which are adjacent to each other along the pipe axis direction Y is defined as a protrusion interval S. Furthermore, when the protrusion 12 is viewed from the inside in the radial direction X of the steel pipe pile 10, an angle between a circumferential direction (W direction in FIG. 2) of the steel pipe pile 10 and the protrusion 12 is defined as a protrusion inclination angle O.
[0031]
The protrusion width w of the protrusion 12 is, for example, 10 mm. The protrusion height h of the protrusion 12 is, for example, 4 mm. However, the protrusion width w and the protrusion height h of the protrusion 12 are not limited to the above-mentioned numerical values. It is preferable that the protrusion inclination angle 0 is 30 or higher and lower than 90 . In addition, it is most preferable that the protrusion inclination angle 0 is 30 or higher and lower than 60 . The reason that it is preferable to set the protrusion inclination angle 0 to the above range will be described later. A
preferable range of the protrusion interval S will be described later. In addition, in this embodiment, a case where the protrusions 12 having a rectangular convex section are formed on the steel pipe pile 10 is exemplified. However, the shape of the convex section of the protrusion 12 may also be a shape other than a rectangular shape.
The protrusion width w of the protrusion 12 is, for example, 10 mm. The protrusion height h of the protrusion 12 is, for example, 4 mm. However, the protrusion width w and the protrusion height h of the protrusion 12 are not limited to the above-mentioned numerical values. It is preferable that the protrusion inclination angle 0 is 30 or higher and lower than 90 . In addition, it is most preferable that the protrusion inclination angle 0 is 30 or higher and lower than 60 . The reason that it is preferable to set the protrusion inclination angle 0 to the above range will be described later. A
preferable range of the protrusion interval S will be described later. In addition, in this embodiment, a case where the protrusions 12 having a rectangular convex section are formed on the steel pipe pile 10 is exemplified. However, the shape of the convex section of the protrusion 12 may also be a shape other than a rectangular shape.
[0032]
The protrusions 12 may be provided on the inner circumferential surface 11 of the steel pipe pile 10 by rolling of a steel strip or the like, or may also be provided by a method of attaching a steel bar through welding or placing weld beads. In addition, portions of a plurality of spiral protrusions 12 may be allowed to intersect each other such that the plurality of protrusions 12 which are inclined in different directions from each other with respect to the circumferential direction W of the steel pipe pile 10 are combined with each other. In addition, a spiral protrusion 12 and a protrusion 12 which is parallel to the circumferential direction W of the steel pipe pile 10 may also be combined with each other.
The protrusions 12 may be provided on the inner circumferential surface 11 of the steel pipe pile 10 by rolling of a steel strip or the like, or may also be provided by a method of attaching a steel bar through welding or placing weld beads. In addition, portions of a plurality of spiral protrusions 12 may be allowed to intersect each other such that the plurality of protrusions 12 which are inclined in different directions from each other with respect to the circumferential direction W of the steel pipe pile 10 are combined with each other. In addition, a spiral protrusion 12 and a protrusion 12 which is parallel to the circumferential direction W of the steel pipe pile 10 may also be combined with each other.
[0033]
In the following description, as shown in FIG. 1, a region in which the protrusions 12 are provided on the inner circumferential surface 11 of the steel pipe pile 10 is defined as a protrusion region Al, and a region in which the protrusions 12 are not provided on the inner circumferential surface 11 of the steel pipe pile 10 is defined as a flat region A2. In addition, as shown in FIG. 1, a region in which the concrete 30 comes into contact with the inner circumferential surface 11 of the steel pipe pile 10 is defined as a stiffening region Bl, and a region in which the concrete 30 does not come into contact with the inner circumferential surface 11 of the steel pipe pile 10 is defined as a raw pipe region B2.
In the following description, as shown in FIG. 1, a region in which the protrusions 12 are provided on the inner circumferential surface 11 of the steel pipe pile 10 is defined as a protrusion region Al, and a region in which the protrusions 12 are not provided on the inner circumferential surface 11 of the steel pipe pile 10 is defined as a flat region A2. In addition, as shown in FIG. 1, a region in which the concrete 30 comes into contact with the inner circumferential surface 11 of the steel pipe pile 10 is defined as a stiffening region Bl, and a region in which the concrete 30 does not come into contact with the inner circumferential surface 11 of the steel pipe pile 10 is defined as a raw pipe region B2.
[0034]
As shown in FIG. 1, the protrusions 12 extend in a spiral shape along the pipe axis direction Y to straddle the boundary between the stiffening region B1 and the raw pipe region B2. In other words, in the protrusion region Al, at least one boundary is present between the stiffening region B1 and the raw pipe region B2. Although the details are described later, there may be a case where two boundaries are present between the stiffening region B1 and the raw pipe region B2 in the protrusion region Al.
As shown in FIG. 1, the protrusions 12 extend in a spiral shape along the pipe axis direction Y to straddle the boundary between the stiffening region B1 and the raw pipe region B2. In other words, in the protrusion region Al, at least one boundary is present between the stiffening region B1 and the raw pipe region B2. Although the details are described later, there may be a case where two boundaries are present between the stiffening region B1 and the raw pipe region B2 in the protrusion region Al.
[0035]
As shown in FIG. 1, the length of the protrusion 12 which extends from the boundary between the stiffening region B1 and the raw pipe region B2 toward the side of the raw pipe region B2 along the pipe axis direction Y is defined as an extension length L.
In other words, the extension length L of the protrusion 12 in the raw pipe region B2 in the pipe axis direction Y is a length obtained by subtracting the length of the stiffening region B1 in the pipe axis direction Y from the length of the protrusion region Al in the pipe axis direction Y.
As shown in FIG. 1, the length of the protrusion 12 which extends from the boundary between the stiffening region B1 and the raw pipe region B2 toward the side of the raw pipe region B2 along the pipe axis direction Y is defined as an extension length L.
In other words, the extension length L of the protrusion 12 in the raw pipe region B2 in the pipe axis direction Y is a length obtained by subtracting the length of the stiffening region B1 in the pipe axis direction Y from the length of the protrusion region Al in the pipe axis direction Y.
[0036]
FIG. 3 is an enlarged view of a region including the boundary between the stiffening region B1 and the raw pipe region B2 in FIG. 1. As shown in FIG. 3, the extension length L of the protrusion 12 in the raw pipe region B2 in the pipe axis direction Y is equal to or greater than a local buckling half-wavelength X of the steel pipe pile 10. Here, the local buckling half-wavelength A, of the steel pipe pile 10 is the length of a buckled portion 13 which is generated in the pipe wall of the raw pipe region B2 due to an external force such as a bending force M, axial force N, and/or shear force Q loaded on the steel pipe pile 10, and is close to the boundary between the stiffening region B1 and the raw pipe region B2 (see FIG. 3).
FIG. 3 is an enlarged view of a region including the boundary between the stiffening region B1 and the raw pipe region B2 in FIG. 1. As shown in FIG. 3, the extension length L of the protrusion 12 in the raw pipe region B2 in the pipe axis direction Y is equal to or greater than a local buckling half-wavelength X of the steel pipe pile 10. Here, the local buckling half-wavelength A, of the steel pipe pile 10 is the length of a buckled portion 13 which is generated in the pipe wall of the raw pipe region B2 due to an external force such as a bending force M, axial force N, and/or shear force Q loaded on the steel pipe pile 10, and is close to the boundary between the stiffening region B1 and the raw pipe region B2 (see FIG. 3).
[0037]
As described above, when it is defined that the outer diameter of the steel pipe pile 10 is D (mm), the plate thickness of the steel pipe pile 10 is t (mm), and the local buckling half-wavelength of the steel pipe pile 10 is X (mm), the local buckling half-wavelength X is expressed by the following Expression (1). In addition, when the Poisson's ratio of the steel pipe pile 10 is defined as v, a constant K in the following Expression (1) is expressed by the following Expression (2).
As described above, when it is defined that the outer diameter of the steel pipe pile 10 is D (mm), the plate thickness of the steel pipe pile 10 is t (mm), and the local buckling half-wavelength of the steel pipe pile 10 is X (mm), the local buckling half-wavelength X is expressed by the following Expression (1). In addition, when the Poisson's ratio of the steel pipe pile 10 is defined as v, a constant K in the following Expression (1) is expressed by the following Expression (2).
[0038]
= KV(D = t) = ( (where, K is a dimensionless constant)
= KV(D = t) = ( (where, K is a dimensionless constant)
[0039]
K= ____________________ ===( 2 ) 402(1¨ V2) 2
K= ____________________ ===( 2 ) 402(1¨ V2) 2
[0040]
In addition, as shown in FIG. 3, when the steel pipe pile 10 is viewed in a section parallel to the pipe axis direction Y, it is preferable that the convex sections of the protrusions 12 are arranged with an interval of equal to or smaller than the local buckling half-wavelength therebetween along the pipe axis direction Y. In other words, it is preferable that the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength k. That is, it is preferable that the relationship between the extension length L, the protrusion interval S, and the local buckling half-wavelength A, of the protrusions 12 satisfies the following Conditional Expression (3).
S < k < L ¨(3)
In addition, as shown in FIG. 3, when the steel pipe pile 10 is viewed in a section parallel to the pipe axis direction Y, it is preferable that the convex sections of the protrusions 12 are arranged with an interval of equal to or smaller than the local buckling half-wavelength therebetween along the pipe axis direction Y. In other words, it is preferable that the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength k. That is, it is preferable that the relationship between the extension length L, the protrusion interval S, and the local buckling half-wavelength A, of the protrusions 12 satisfies the following Conditional Expression (3).
S < k < L ¨(3)
[0041]
According to the composite structure 1 having the above-described configuration, it is possible to realize the enhancement of local buckling resistance in the boundary between the stiffening region B1 and the raw pipe region B2 of the steel pipe pile 10 without increasing the plate thickness of the steel pipe pile 10 and using a stiffening material such as stiffener. That is, according to the composite structure 1 having the above-described configuration, while satisfying the conditions in which the balance between the advantage and the disadvantage caused by the plate thickness t of the steel pipe pile 10 (conditions in which the ratio D/t obtained by dividing the outer diameter D by the plate thickness t is 50 or higher and 100 or lower), the local buckling resistance in the boundary between the stiffening region B1 and the raw pipe region B2 can be enhanced.
According to the composite structure 1 having the above-described configuration, it is possible to realize the enhancement of local buckling resistance in the boundary between the stiffening region B1 and the raw pipe region B2 of the steel pipe pile 10 without increasing the plate thickness of the steel pipe pile 10 and using a stiffening material such as stiffener. That is, according to the composite structure 1 having the above-described configuration, while satisfying the conditions in which the balance between the advantage and the disadvantage caused by the plate thickness t of the steel pipe pile 10 (conditions in which the ratio D/t obtained by dividing the outer diameter D by the plate thickness t is 50 or higher and 100 or lower), the local buckling resistance in the boundary between the stiffening region B1 and the raw pipe region B2 can be enhanced.
[0042]
Hereinafter, as shown in FIG. 4, in each of a case where shear force Q is loaded on the steel pipe pile 10 and a case where axial force N is loaded on the steel pipe pile 10, analysis results of the local buckling resistance of the steel pipe pile 10 analyzed through the finite element method (FEM) using shell elements are described.
Hereinafter, as shown in FIG. 4, in each of a case where shear force Q is loaded on the steel pipe pile 10 and a case where axial force N is loaded on the steel pipe pile 10, analysis results of the local buckling resistance of the steel pipe pile 10 analyzed through the finite element method (FEM) using shell elements are described.
[0043]
In the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the protrusion inclination angle O of the protrusion 12 was set to 30 , and the protrusion interval S between the protrusions 12 was set to 100 mm. Under such conditions, the local buckling half-wavelength X of the steel pipe pile 10 becomes 199 mm.
Under the above conditions, analysis results of the relationship between the extension length L of the protrusion 12 and the local buckling resistance against shear force Q (the maximum strength against shear force Q) in a case where the extension length L of the protrusion 12 was changed in a range of 0 mm to 500 mm, are shown in the following Table 1. In addition, in the following Table 1, when the extension length L of the protrusion 12 is 199 mm or greater, the condition in which the extension length L
of the protrusion 12 is equal to or greater than the local buckling half-wavelength X of the steel pipe pile 10 is satisfied.
In the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the protrusion inclination angle O of the protrusion 12 was set to 30 , and the protrusion interval S between the protrusions 12 was set to 100 mm. Under such conditions, the local buckling half-wavelength X of the steel pipe pile 10 becomes 199 mm.
Under the above conditions, analysis results of the relationship between the extension length L of the protrusion 12 and the local buckling resistance against shear force Q (the maximum strength against shear force Q) in a case where the extension length L of the protrusion 12 was changed in a range of 0 mm to 500 mm, are shown in the following Table 1. In addition, in the following Table 1, when the extension length L of the protrusion 12 is 199 mm or greater, the condition in which the extension length L
of the protrusion 12 is equal to or greater than the local buckling half-wavelength X of the steel pipe pile 10 is satisfied.
[0044]
[Table 1]
L(mm) Lit(De Qmax(kN) Qmax/Q0 0 = 0 794 1 100 1.23 810 1.020 199 2.44 834 1.049 250 3.08 834 1.049 500 6.15 836 1.053
[Table 1]
L(mm) Lit(De Qmax(kN) Qmax/Q0 0 = 0 794 1 100 1.23 810 1.020 199 2.44 834 1.049 250 3.08 834 1.049 500 6.15 836 1.053
[0045]
In Table 1, Qmax (kN) represents the shear force Q at a point in time when local buckling finally occurs in the steel pipe pile 10 and the shear force Q
reaches to the maximum strength in a case where the shear force Q loaded on the upper end portion of the steel pipe pile 10 is gradually increased to forcibly deform the steel pipe pile 10.
That is, Qmax represents the local buckling resistance (the maximum strength against the shear force Q) of the steel pipe pile 10 against the shear force Q.
The maximum strength Qmax (-794 kN) when the extension length L is 0 mm, that is, when the protrusion 12 is not present in the raw pipe region B2, is defined as a reference strength QO. Therefore, in Table 1, when the extension length L of the protrusion 12 is 0 mm, the ratio (=Qmax/Q0) obtained by dividing the maximum strength Qmax by the reference strength QO becomes "1". In Table 1, "Qmax/Q0" is a dimensionless number representing the ratio of an increase in the maximum strength Qmax with respect to a change in the extension length L of the protrusion 12.
In Table 1, Qmax (kN) represents the shear force Q at a point in time when local buckling finally occurs in the steel pipe pile 10 and the shear force Q
reaches to the maximum strength in a case where the shear force Q loaded on the upper end portion of the steel pipe pile 10 is gradually increased to forcibly deform the steel pipe pile 10.
That is, Qmax represents the local buckling resistance (the maximum strength against the shear force Q) of the steel pipe pile 10 against the shear force Q.
The maximum strength Qmax (-794 kN) when the extension length L is 0 mm, that is, when the protrusion 12 is not present in the raw pipe region B2, is defined as a reference strength QO. Therefore, in Table 1, when the extension length L of the protrusion 12 is 0 mm, the ratio (=Qmax/Q0) obtained by dividing the maximum strength Qmax by the reference strength QO becomes "1". In Table 1, "Qmax/Q0" is a dimensionless number representing the ratio of an increase in the maximum strength Qmax with respect to a change in the extension length L of the protrusion 12.
[0046]
FIG. 5 shows a graph in which "L/-q(1).0" in Table 1 is set as the horizontal axis, and "Qmax/Q0" in Table 1 is set as the vertical axis. As shown in FIG. 5, when "Lhi(Dt)"
becomes 2.44 or higher, "Qmax/Q0" becomes 1.049 or higher. That is, when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength X, (=199 mm) of the steel pipe pile 10 is satisfied, the ratio of the increase in the maximum strength Q. of the steel pipe pile 10 against the shear force Q becomes 4.9% or higher. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength X, of the steel pipe pile 10 is satisfied, the local buckling resistance of the steel pipe pile 10 against the shear force Q is significantly increased.
FIG. 5 shows a graph in which "L/-q(1).0" in Table 1 is set as the horizontal axis, and "Qmax/Q0" in Table 1 is set as the vertical axis. As shown in FIG. 5, when "Lhi(Dt)"
becomes 2.44 or higher, "Qmax/Q0" becomes 1.049 or higher. That is, when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength X, (=199 mm) of the steel pipe pile 10 is satisfied, the ratio of the increase in the maximum strength Q. of the steel pipe pile 10 against the shear force Q becomes 4.9% or higher. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength X, of the steel pipe pile 10 is satisfied, the local buckling resistance of the steel pipe pile 10 against the shear force Q is significantly increased.
[0047]
Next, in the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the extension length L of the protrusion 12 was set to 500 mm, and the protrusion interval S between the protrusions 12 was set to 100 mm. That is, the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength X (=199 mm) of the steel pipe pile 10 is satisfied.
Under such conditions, analysis results of the relationship between the protrusion inclination angle 0, the maximum strength Qmax of the steel pipe pile 10 against shear force Q, and "Qmax/Q0" in a case where the protrusion inclination angle 0 of the protrusion 12 was changed in a range of 10 to 90 are shown in the following Table 2.
Next, in the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the extension length L of the protrusion 12 was set to 500 mm, and the protrusion interval S between the protrusions 12 was set to 100 mm. That is, the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength X (=199 mm) of the steel pipe pile 10 is satisfied.
Under such conditions, analysis results of the relationship between the protrusion inclination angle 0, the maximum strength Qmax of the steel pipe pile 10 against shear force Q, and "Qmax/Q0" in a case where the protrusion inclination angle 0 of the protrusion 12 was changed in a range of 10 to 90 are shown in the following Table 2.
[0048]
[Table 2]
) Omax('N) Orna x/00 814 1.025 819 1.031 39L. ______________________________ 836 1.053 45 855 1.077 80 849 1.069 75 858 1.081 90 _______________________________ 82 1.085
[Table 2]
) Omax('N) Orna x/00 814 1.025 819 1.031 39L. ______________________________ 836 1.053 45 855 1.077 80 849 1.069 75 858 1.081 90 _______________________________ 82 1.085
[0049]
5 FIG. 6 shows a graph in which the protrusion inclination angle 0 in Table 2 is set as the horizontal axis, and "Qmax/Q0" in Table 2 is set as the vertical axis.
As shown in FIG. 6, when the protrusion inclination angle 0 becomes 30 or higher, "Qmax/Q0"
becomes 1.053 to 1.085. That is, when the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the ratio of the increase in the maximum strength 10 Qmax of the steel pipe pile 10 against the shear force Q becomes 5.3% to 8.5. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength of the steel pipe pile 10 is satisfied and the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the local buckling resistance of the steel pipe pile 10 15 against the shear force Q is more significantly increased.
5 FIG. 6 shows a graph in which the protrusion inclination angle 0 in Table 2 is set as the horizontal axis, and "Qmax/Q0" in Table 2 is set as the vertical axis.
As shown in FIG. 6, when the protrusion inclination angle 0 becomes 30 or higher, "Qmax/Q0"
becomes 1.053 to 1.085. That is, when the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the ratio of the increase in the maximum strength 10 Qmax of the steel pipe pile 10 against the shear force Q becomes 5.3% to 8.5. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength of the steel pipe pile 10 is satisfied and the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the local buckling resistance of the steel pipe pile 10 15 against the shear force Q is more significantly increased.
[0050]
Next, in the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the 20 protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the extension length L of the protrusion 12 was set to 3000 mm, and the protrusion interval S between the protrusions 12 was set to 100 mm. That is, the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k (=199 mm) of the steel pipe pile 10 is satisfied.
In addition, setting the extension length L of the protrusion 12 to 3000 mm means that the protrusion 12 is formed over the entire length of the steel pipe pile 10.
Under such conditions, analysis results of the relationship between the protrusion inclination angle 0 and the local buckling resistance against axial force N (the maximum strength against axial force N) in a case where the protrusion inclination angle 0 of the protrusion 12 was changed in a range of 5 to 90 are shown in the following Table 3.
Next, in the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the 20 protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the extension length L of the protrusion 12 was set to 3000 mm, and the protrusion interval S between the protrusions 12 was set to 100 mm. That is, the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k (=199 mm) of the steel pipe pile 10 is satisfied.
In addition, setting the extension length L of the protrusion 12 to 3000 mm means that the protrusion 12 is formed over the entire length of the steel pipe pile 10.
Under such conditions, analysis results of the relationship between the protrusion inclination angle 0 and the local buckling resistance against axial force N (the maximum strength against axial force N) in a case where the protrusion inclination angle 0 of the protrusion 12 was changed in a range of 5 to 90 are shown in the following Table 3.
[0051]
[Table 3]
f __________ K
k* I aNni3)( Onl KIN) ax/NV
None 7581 1 5 6948 0.916 10 7001 0.924 15 6913 0.912 20 7120 _______ 0.939 25 7667 1.011 30 7949 1.049 45 8154 1.076 60 8288 1.093 75 8336 1.100 90 8323 1.098
[Table 3]
f __________ K
k* I aNni3)( Onl KIN) ax/NV
None 7581 1 5 6948 0.916 10 7001 0.924 15 6913 0.912 20 7120 _______ 0.939 25 7667 1.011 30 7949 1.049 45 8154 1.076 60 8288 1.093 75 8336 1.100 90 8323 1.098
[0052]
In Table 3, Nina, (kN) represents the axial force N at a point in time when local buckling finally occurs in the steel pipe pile 10 and the axial force N
reaches the maximum strength in a case where the axial force N loaded on the steel pipe pile 10 is gradually increased to forcibly deform the steel pipe pile 10. That is, Nmax represents the local buckling resistance (the maximum strength against the axial force N) of the steel pipe pile 10 against the axial force N.
The maximum strength Nnia, (-7580 kN) when the protrusion inclination angle 0 is "none" (when the protrusion 12 is not present in the steel pipe pile 10) is defined as a reference strength NO. Therefore, in Table 3, when the protrusion inclination angle 0 is "none", the ratio (¨Nmax/NO) obtained by dividing the maximum strength Nmax by the reference strength NO becomes "1". "Nmax/NO" is a dimensionless number representing the ratio of an increase in the maximum strength Nmax with respect to a change in the protrusion inclination angle 0 of the protrusion 12.
In Table 3, Nina, (kN) represents the axial force N at a point in time when local buckling finally occurs in the steel pipe pile 10 and the axial force N
reaches the maximum strength in a case where the axial force N loaded on the steel pipe pile 10 is gradually increased to forcibly deform the steel pipe pile 10. That is, Nmax represents the local buckling resistance (the maximum strength against the axial force N) of the steel pipe pile 10 against the axial force N.
The maximum strength Nnia, (-7580 kN) when the protrusion inclination angle 0 is "none" (when the protrusion 12 is not present in the steel pipe pile 10) is defined as a reference strength NO. Therefore, in Table 3, when the protrusion inclination angle 0 is "none", the ratio (¨Nmax/NO) obtained by dividing the maximum strength Nmax by the reference strength NO becomes "1". "Nmax/NO" is a dimensionless number representing the ratio of an increase in the maximum strength Nmax with respect to a change in the protrusion inclination angle 0 of the protrusion 12.
[0053]
FIG. 7 shows a graph in which the protrusion inclination angle 0 in Table 3 is set as the horizontal axis, and "Nmax/NO" in Table 3 is set as the vertical axis.
As shown in FIG. 7, when the protrusion inclination angle 0 becomes 30 or higher, "Nmax/NO"
becomes 1.049 to 1.100. That is, when the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the ratio of the increase in the maximum strength Nmax of the steel pipe pile 10 against the axial force N becomes 4.9% to 10.0%. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10 is satisfied and the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the local buckling resistance of the steel pipe pile 10 against the axial force N is significantly increased.
FIG. 7 shows a graph in which the protrusion inclination angle 0 in Table 3 is set as the horizontal axis, and "Nmax/NO" in Table 3 is set as the vertical axis.
As shown in FIG. 7, when the protrusion inclination angle 0 becomes 30 or higher, "Nmax/NO"
becomes 1.049 to 1.100. That is, when the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the ratio of the increase in the maximum strength Nmax of the steel pipe pile 10 against the axial force N becomes 4.9% to 10.0%. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10 is satisfied and the condition in which the protrusion inclination angle 0 is 30 or higher is satisfied, the local buckling resistance of the steel pipe pile 10 against the axial force N is significantly increased.
[0054]
As described above, from the analysis results shown in Tables 2 and 3 (FIGS. 6 and 7), a condition in which the protrusion inclination angle 0 of the protrusion 12 is 30 or higher and 90 or lower is derived as one of the conditions for further enhancing the local buckling resistance of the steel pipe pile 10. However, in a case where the protrusion inclination angle 0 is 90 , the bond strength between the steel pipe pile 10 and the concrete 30 cannot be sufficiently obtained. Therefore, in this embodiment, as one of the conditions for further enhancing the local buckling resistance of the steel pipe pile 10, a condition in which the protrusion inclination angle 0 of the protrusion 12 is 30 or higher and lower than 90 is employed.
As described above, from the analysis results shown in Tables 2 and 3 (FIGS. 6 and 7), a condition in which the protrusion inclination angle 0 of the protrusion 12 is 30 or higher and 90 or lower is derived as one of the conditions for further enhancing the local buckling resistance of the steel pipe pile 10. However, in a case where the protrusion inclination angle 0 is 90 , the bond strength between the steel pipe pile 10 and the concrete 30 cannot be sufficiently obtained. Therefore, in this embodiment, as one of the conditions for further enhancing the local buckling resistance of the steel pipe pile 10, a condition in which the protrusion inclination angle 0 of the protrusion 12 is 30 or higher and lower than 90 is employed.
[0055]
From the analysis results shown in Tables 2 and 3 (FIGS. 6 and 7), as the most preferable condition, a condition in which the protrusion inclination angle 0 of the protrusion 12 is 30 or higher and 60 or lower is derived. Here, as shown in FIGS. 6 and 7, 30 which is the lower limit of the protrusion inclination angle 0 is a value at which the ratios of the increases in the maximum strength Qmax against the shear force Q
and in the maximum strength Nmax against the axial force N are significantly increased.
In addition, 60 which is the upper limit of the protrusion inclination angle 0 is a value at which the ratios of the increases in the maximum strength Qmax against the shear force Q
and in the maximum strength Nina, against the axial force N are not significantly increased even when the protrusion inclination angle 0 is further increased.
From the analysis results shown in Tables 2 and 3 (FIGS. 6 and 7), as the most preferable condition, a condition in which the protrusion inclination angle 0 of the protrusion 12 is 30 or higher and 60 or lower is derived. Here, as shown in FIGS. 6 and 7, 30 which is the lower limit of the protrusion inclination angle 0 is a value at which the ratios of the increases in the maximum strength Qmax against the shear force Q
and in the maximum strength Nmax against the axial force N are significantly increased.
In addition, 60 which is the upper limit of the protrusion inclination angle 0 is a value at which the ratios of the increases in the maximum strength Qmax against the shear force Q
and in the maximum strength Nina, against the axial force N are not significantly increased even when the protrusion inclination angle 0 is further increased.
[0056]
Next, in the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the protrusion inclination angle 0 of the protrusion 12 was set to 45 , and the extension length L of the protrusion 12 was set to 500 mm. That is, the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength A, (=199 mm) of the steel pipe pile 10 is satisfied.
Under these conditions, analysis results of the relationship between the protrusion interval S between the protrusions 12 and the local buckling resistance against shear force Q (the maximum strength against shear force Q) in a case where the protrusion interval S between the protrusions 12 was changed in a range of 0 mm to 300 mm are shown in the following Table 4. In addition, in the following Table 4, when the protrusion interval S between the protrusions 12 is 199 mm or smaller, a condition in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength A, of the steel pipe pile 10 is satisfied.
Next, in the FEM analysis, the outer diameter D of the steel pipe pile 10 was set to 1000 mm, the plate thickness t of the steel pipe pile 10 was set to 6.6 mm, the Poisson's ratio v of the steel pipe pile 10 was set to 0.30, the protrusion height h of the protrusion 12 was set to 4 mm, the protrusion width w of the protrusion 12 was set to 10 mm, the protrusion inclination angle 0 of the protrusion 12 was set to 45 , and the extension length L of the protrusion 12 was set to 500 mm. That is, the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength A, (=199 mm) of the steel pipe pile 10 is satisfied.
Under these conditions, analysis results of the relationship between the protrusion interval S between the protrusions 12 and the local buckling resistance against shear force Q (the maximum strength against shear force Q) in a case where the protrusion interval S between the protrusions 12 was changed in a range of 0 mm to 300 mm are shown in the following Table 4. In addition, in the following Table 4, when the protrusion interval S between the protrusions 12 is 199 mm or smaller, a condition in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength A, of the steel pipe pile 10 is satisfied.
[0057]
[Table 4]
Vnlrn) Sir(Dt) Omax(kN) Omax/00 None '794 1 0 0 , 940 1.184 60 0.74 871 1.097 100 1.23 854 1.076 150 1.85 821 1.034 199 2.44 811 1.022 300J 3.69 802 1.010
[Table 4]
Vnlrn) Sir(Dt) Omax(kN) Omax/00 None '794 1 0 0 , 940 1.184 60 0.74 871 1.097 100 1.23 854 1.076 150 1.85 821 1.034 199 2.44 811 1.022 300J 3.69 802 1.010
[0058]
In Table 4, as in Tables 1 and 2, Qõ,aõ (kN) represents the shear force Q at a point in time when local buckling finally occurs in the steel pipe pile 10 and the shear force Q
reaches the maximum strength in a case where the shear force Q loaded on the upper end portion of the steel pipe pile 10 is gradually increased to forcibly deform the steel pipe pile 10. That is, Qmax represents the local buckling resistance (the maximum strength against the shear force Q) of the steel pipe pile 10 against the shear force Q.
The maximum strength Qmax (-794 kN) when the protrusion interval S is "none"
(when the protrusion 12 is not present in the steel pipe pile 10) is defined as a reference strength Q0. Therefore, in Table 4, when the protrusion interval S is "none", the ratio (=Qmax/Q0) obtained by dividing the maximum strength Q. by the reference strength QO becomes "1". In Table 4, "Qmax/Q0" is a dimensionless number representing the ratio of an increase in the maximum strength Qmax with respect to a change in the protrusion interval S between the protrusions 12.
In Table 4, as in Tables 1 and 2, Qõ,aõ (kN) represents the shear force Q at a point in time when local buckling finally occurs in the steel pipe pile 10 and the shear force Q
reaches the maximum strength in a case where the shear force Q loaded on the upper end portion of the steel pipe pile 10 is gradually increased to forcibly deform the steel pipe pile 10. That is, Qmax represents the local buckling resistance (the maximum strength against the shear force Q) of the steel pipe pile 10 against the shear force Q.
The maximum strength Qmax (-794 kN) when the protrusion interval S is "none"
(when the protrusion 12 is not present in the steel pipe pile 10) is defined as a reference strength Q0. Therefore, in Table 4, when the protrusion interval S is "none", the ratio (=Qmax/Q0) obtained by dividing the maximum strength Q. by the reference strength QO becomes "1". In Table 4, "Qmax/Q0" is a dimensionless number representing the ratio of an increase in the maximum strength Qmax with respect to a change in the protrusion interval S between the protrusions 12.
[0059]
FIG. 8 shows a graph in which "Shi(D.0" in Table 4 is set as the horizontal axis, and "Q./Q0" in Table 4 is set as the vertical axis. As shown in FIG. 8, when "StV(Dt)"
becomes 2.44 or lower, "Qmax/Q0" becomes 1.022 or higher. That is, when the condition in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength k (=199 mm) of the steel pipe pile 10 is satisfied, the ratio of the increase in the maximum strength Qmax of the steel pipe pile 10 against the shear force Q becomes 2.2% or higher. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10 is satisfied and the condition in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength X of the steel pipe pile 10 (that is, conditions specified in the above Expression (3)) is satisfied, the local buckling resistance of the steel pipe pile 10 against the shear force Q is significantly increased.
FIG. 8 shows a graph in which "Shi(D.0" in Table 4 is set as the horizontal axis, and "Q./Q0" in Table 4 is set as the vertical axis. As shown in FIG. 8, when "StV(Dt)"
becomes 2.44 or lower, "Qmax/Q0" becomes 1.022 or higher. That is, when the condition in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength k (=199 mm) of the steel pipe pile 10 is satisfied, the ratio of the increase in the maximum strength Qmax of the steel pipe pile 10 against the shear force Q becomes 2.2% or higher. As described above, it was confirmed that when the condition in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10 is satisfied and the condition in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength X of the steel pipe pile 10 (that is, conditions specified in the above Expression (3)) is satisfied, the local buckling resistance of the steel pipe pile 10 against the shear force Q is significantly increased.
[0060]
As described above, according to the composite structure 1 according to this embodiment which satisfies the condition (first condition) in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10, the condition (second condition) in which the protrusion inclination angle 0 is 30 or higher and lower than 90 , and the condition (third condition) in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength k of the steel pipe pile 10, it is possible to realize the enhancement of local buckling resistance in the boundary between the stiffening region B1 and the raw pipe region B2 while satisfying the conditions in which the balance between the advantage and the disadvantage caused by the plate thickness t of the steel pipe pile 10 is optimized (the conditions in which the ratio D/t obtained by dividing the outer diameter D by the plate thickness t is 50 or higher and 100 or lower).
As described above, according to the composite structure 1 according to this embodiment which satisfies the condition (first condition) in which the extension length L of the protrusion 12 is equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10, the condition (second condition) in which the protrusion inclination angle 0 is 30 or higher and lower than 90 , and the condition (third condition) in which the protrusion interval S between the protrusions 12 is equal to or smaller than the local buckling half-wavelength k of the steel pipe pile 10, it is possible to realize the enhancement of local buckling resistance in the boundary between the stiffening region B1 and the raw pipe region B2 while satisfying the conditions in which the balance between the advantage and the disadvantage caused by the plate thickness t of the steel pipe pile 10 is optimized (the conditions in which the ratio D/t obtained by dividing the outer diameter D by the plate thickness t is 50 or higher and 100 or lower).
[0061]
In addition, as understood from the analysis results, a composite structure which satisfies at least the first condition can obtain the above effects. However, in order to further enhance the local buckling resistance of the steel pipe pile 10, it is preferable that a composite structure which satisfies at least one of the second and third conditions in addition to the first condition is employed.
In addition, as understood from the analysis results, a composite structure which satisfies at least the first condition can obtain the above effects. However, in order to further enhance the local buckling resistance of the steel pipe pile 10, it is preferable that a composite structure which satisfies at least one of the second and third conditions in addition to the first condition is employed.
[0062]
Incidentally, in the embodiment, a case where the protrusions 12 are formed over the entire section of the stiffening region B1 (that is, a case where the protrusions 12 are formed over the entire section of the inner circumferential surface 11 which comes into contact with the concrete 30) is exemplified. However, the protrusions 12 do not need to be formed over the entire section of the stiffening region B1 as long as at least the first condition is satisfied. For example, as shown in FIG. 9, the stiffening region B1 may also include a region in which the protrusions 12 are not formed (flat region A2) and a region in which the protrusions 12 are formed (protrusion region A1). However, for high bond strength of the steel pipe pile 10 and the concrete 30, it is preferable that the protrusions 12 are formed over the entire section of the stiffening region Bl.
Incidentally, in the embodiment, a case where the protrusions 12 are formed over the entire section of the stiffening region B1 (that is, a case where the protrusions 12 are formed over the entire section of the inner circumferential surface 11 which comes into contact with the concrete 30) is exemplified. However, the protrusions 12 do not need to be formed over the entire section of the stiffening region B1 as long as at least the first condition is satisfied. For example, as shown in FIG. 9, the stiffening region B1 may also include a region in which the protrusions 12 are not formed (flat region A2) and a region in which the protrusions 12 are formed (protrusion region A1). However, for high bond strength of the steel pipe pile 10 and the concrete 30, it is preferable that the protrusions 12 are formed over the entire section of the stiffening region Bl.
[0063]
In addition, in the embodiment, a case where one boundary is present between the stiffening region B1 and the raw pipe region B2 in the protrusion region Al is exemplified. However, as shown in FIG. 10, a composite structure in which two boundaries are present between the stiffening region B1 and the raw pipe region B2 in the protrusion region A1 may also be employed. Even in the composite structure shown in FIG. 10, at least the first condition needs to be satisfied. That is, in FIG.
10, both of the extension length L of the protrusions 12 that extend upward from the upper end of the stiffening region B1 in the pipe axis direction Y and the extension length L
of the protrusions 12 that extend downward from the lower end of the stiffening region B1 in the pipe axis direction Y need to be set to a length of equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10.
In addition, in the embodiment, a case where one boundary is present between the stiffening region B1 and the raw pipe region B2 in the protrusion region Al is exemplified. However, as shown in FIG. 10, a composite structure in which two boundaries are present between the stiffening region B1 and the raw pipe region B2 in the protrusion region A1 may also be employed. Even in the composite structure shown in FIG. 10, at least the first condition needs to be satisfied. That is, in FIG.
10, both of the extension length L of the protrusions 12 that extend upward from the upper end of the stiffening region B1 in the pipe axis direction Y and the extension length L
of the protrusions 12 that extend downward from the lower end of the stiffening region B1 in the pipe axis direction Y need to be set to a length of equal to or greater than the local buckling half-wavelength k of the steel pipe pile 10.
[0064]
In addition, in the embodiment, the H-shaped steel 20 is exemplified as the joint object member joined to the steel pipe pile 10. However, any joint object member may be employed as long as the joint object member has a shape that can be inserted into the steel pipe pile 10.
In addition, in the embodiment, a case where the protrusions 12 are provided on the inner circumferential surface 11 of the steel pipe pile 10 is exemplified.
However, protrusions which protrude outward in the radial direction of the steel pipe pile 10 from the outer circumferential surface of the steel pipe pile 10 and extend in a spiral shape along the pipe axis direction Y of the steel pipe pile 10 may also be provided in addition to the protrusions 12.
In addition, in the embodiment, the H-shaped steel 20 is exemplified as the joint object member joined to the steel pipe pile 10. However, any joint object member may be employed as long as the joint object member has a shape that can be inserted into the steel pipe pile 10.
In addition, in the embodiment, a case where the protrusions 12 are provided on the inner circumferential surface 11 of the steel pipe pile 10 is exemplified.
However, protrusions which protrude outward in the radial direction of the steel pipe pile 10 from the outer circumferential surface of the steel pipe pile 10 and extend in a spiral shape along the pipe axis direction Y of the steel pipe pile 10 may also be provided in addition to the protrusions 12.
[0065]
As described above, according to the embodiment, by satisfying at least the first condition, the difference in the stiffness and the strength of this structure between the stiffening region B1 and the raw pipe region B2 is reduced in the boundary between the stiffening region B1 and the raw pipe region B2.
As described above, according to the embodiment, by satisfying at least the first condition, the difference in the stiffness and the strength of this structure between the stiffening region B1 and the raw pipe region B2 is reduced in the boundary between the stiffening region B1 and the raw pipe region B2.
[0066]
Accordingly, the stiffness and the strength of this structure are gradually decreased from the stiffening region B1 to the raw pipe region B2 in the boundary between the stiffening region B1 and the raw pipe region B2, and thus it is possible to prevent rapid decreases in the stiffness and the strength of the steel pipe (the steel pipe pile 10). In addition, according to the embodiment, the occurrence of stress concentration on the steel pipe caused by an external force such as a bending force M, axial force N, and/or shear force Q in the boundary between the stiffening region B1 and the raw pipe region B2 of the steel pipe is prevented, and thus it is possible to prevent the occurrence of local buckling in the raw pipe region B2.
Accordingly, the stiffness and the strength of this structure are gradually decreased from the stiffening region B1 to the raw pipe region B2 in the boundary between the stiffening region B1 and the raw pipe region B2, and thus it is possible to prevent rapid decreases in the stiffness and the strength of the steel pipe (the steel pipe pile 10). In addition, according to the embodiment, the occurrence of stress concentration on the steel pipe caused by an external force such as a bending force M, axial force N, and/or shear force Q in the boundary between the stiffening region B1 and the raw pipe region B2 of the steel pipe is prevented, and thus it is possible to prevent the occurrence of local buckling in the raw pipe region B2.
[0067]
In addition, according to the embodiment, the local buckling resistance of the steel pipe in the boundary between the stiffening region B1 and the raw pipe region B2 of the steel pipe can be enhanced, and thus it is possible to sufficiently support a building structure or the like at a junction of the steel pipe and the joint object member.
In addition, according to the embodiment, the local buckling resistance of the steel pipe in the boundary between the stiffening region B1 and the raw pipe region B2 of the steel pipe can be enhanced, and thus it is possible to sufficiently support a building structure or the like at a junction of the steel pipe and the joint object member.
[0068]
In addition, in the embodiment, when the protrusions (12) of the steel pipe are viewed from the inside in the radial direction X of the steel pipe, the angle between the circumferential direction W of the steel pipe and the protrusion is set to be 30 or higher and lower than 90 .
In addition, in the embodiment, when the protrusions (12) of the steel pipe are viewed from the inside in the radial direction X of the steel pipe, the angle between the circumferential direction W of the steel pipe and the protrusion is set to be 30 or higher and lower than 90 .
[0069]
Accordingly, in the embodiment, a thin section of the steel pipe in which the protrusion is not present is not continuous in a section of the steel pipe in the pipe circumferential direction thereof. As a result, the local buckling resistance of the steel pipe can be enhanced, and thus it is possible to prevent the occurrence of the local buckling in the raw pipe region B2.
Accordingly, in the embodiment, a thin section of the steel pipe in which the protrusion is not present is not continuous in a section of the steel pipe in the pipe circumferential direction thereof. As a result, the local buckling resistance of the steel pipe can be enhanced, and thus it is possible to prevent the occurrence of the local buckling in the raw pipe region B2.
[0070]
In addition, according to the embodiment, the protrusions are provided in a spiral shape along the pipe axis direction Y of the steel pipe, and thus the bond strength between the steel pipe and the concrete (30) can be enhanced. In addition, in order to enhance the bond strength between the steel pipe and the concrete, protrusions provided in the stiffening region B1 may be provided to extend along the pipe axis direction Y of the steel pipe. Therefore, it is possible to efficiently manufacture a steel pipe having enhanced local buckling resistance. Furthermore, according to the embodiment, for example, in a case where a steel strip provided with protrusions is formed into a spiral shape, it is possible to significantly enhance the manufacturing efficiency of the steel pipe.
In addition, according to the embodiment, the protrusions are provided in a spiral shape along the pipe axis direction Y of the steel pipe, and thus the bond strength between the steel pipe and the concrete (30) can be enhanced. In addition, in order to enhance the bond strength between the steel pipe and the concrete, protrusions provided in the stiffening region B1 may be provided to extend along the pipe axis direction Y of the steel pipe. Therefore, it is possible to efficiently manufacture a steel pipe having enhanced local buckling resistance. Furthermore, according to the embodiment, for example, in a case where a steel strip provided with protrusions is formed into a spiral shape, it is possible to significantly enhance the manufacturing efficiency of the steel pipe.
[0071]
In the related art, in a case in which it is desired to only ensure the bond strength between a steel pipe and concrete, protrusions inclined at about 10 to 20 with respect to the circumferential direction W of a steel pipe are provided in the steel pipe by forming a steel strip provided with the protrusions into a spiral shape, or the like.
In the related art, in a case in which it is desired to only ensure the bond strength between a steel pipe and concrete, protrusions inclined at about 10 to 20 with respect to the circumferential direction W of a steel pipe are provided in the steel pipe by forming a steel strip provided with the protrusions into a spiral shape, or the like.
[0072]
Contrary to this, according to the embodiment, a manufacturing process of a steel pipe provided with protrusions is directly used to ensure the bond strength between the steel pipe and concrete, and the protrusions are inclined at an angle of 30 or higher with respect to the circumferential direction W of the steel pipe in order to enhance the local buckling resistance of the steel pipe, thereby efficiently providing the protrusions in the steel pipe.
Contrary to this, according to the embodiment, a manufacturing process of a steel pipe provided with protrusions is directly used to ensure the bond strength between the steel pipe and concrete, and the protrusions are inclined at an angle of 30 or higher with respect to the circumferential direction W of the steel pipe in order to enhance the local buckling resistance of the steel pipe, thereby efficiently providing the protrusions in the steel pipe.
[0073]
Particularly, according to the embodiment, by setting the protrusion inclination angle 0 to be 30 or higher and lower than 90 (most preferably, 30 05.60 ), it is possible to reliably prevent the occurrence of local buckling, in which the pipe wall is crushed into a bellows shape, in the steel pipe. In addition, by allowing the concrete to be reliably adhered to the inner circumferential surface (11) of the steel pipe, it is possible to sufficiently ensure the bond strength between the steel pipe and the concrete.
Particularly, according to the embodiment, by setting the protrusion inclination angle 0 to be 30 or higher and lower than 90 (most preferably, 30 05.60 ), it is possible to reliably prevent the occurrence of local buckling, in which the pipe wall is crushed into a bellows shape, in the steel pipe. In addition, by allowing the concrete to be reliably adhered to the inner circumferential surface (11) of the steel pipe, it is possible to sufficiently ensure the bond strength between the steel pipe and the concrete.
[0074]
In addition, in the embodiment, when the steel pipe is viewed in a section parallel to the pipe axis direction Y, the convex sections of the protrusions are arranged with an interval equal to or smaller than the local buckling half-wavelength k of the steel pipe therebetween along the pipe axis direction Y. That is, the protrusion interval S
between the protrusions is set to be equal to or smaller than the local buckling half-wavelength A, of the steel pipe.
In addition, in the embodiment, when the steel pipe is viewed in a section parallel to the pipe axis direction Y, the convex sections of the protrusions are arranged with an interval equal to or smaller than the local buckling half-wavelength k of the steel pipe therebetween along the pipe axis direction Y. That is, the protrusion interval S
between the protrusions is set to be equal to or smaller than the local buckling half-wavelength A, of the steel pipe.
[0075]
Accordingly, it is possible to prevent the occurrence of local buckling in the raw pipe region B2 due to an external force loaded on the steel pipe between the protrusions which are adjacent to each other along the pipe axis direction Y of the steel pipe.
Accordingly, it is possible to prevent the occurrence of local buckling in the raw pipe region B2 due to an external force loaded on the steel pipe between the protrusions which are adjacent to each other along the pipe axis direction Y of the steel pipe.
[0076]
In addition, by setting the protrusion interval S between the protrusions to be equal to or smaller than the local buckling half-wavelength k of the steel pipe, the local buckling resistance of the steel pipe is further increased. As a result, it is possible to significantly enhance the strength of the steel pipe.
In addition, by setting the protrusion interval S between the protrusions to be equal to or smaller than the local buckling half-wavelength k of the steel pipe, the local buckling resistance of the steel pipe is further increased. As a result, it is possible to significantly enhance the strength of the steel pipe.
[0077]
While the embodiment of the present invention has been described above in detail, the present invention is not limited to the above-described embodiment, and the technical scope of the present invention should not be construed as being limited by the embodiment.
While the embodiment of the present invention has been described above in detail, the present invention is not limited to the above-described embodiment, and the technical scope of the present invention should not be construed as being limited by the embodiment.
[0078]
For example, the present invention can also be applied to a beam-column connection, in which protrusions are provided in a column member or a steel pipe used as a sheath pipe, the column member (joint object member) is inserted into the sheath pipe to which a beam member is connected, and concrete fills a space between the sheath pipe and the column member.
[Brief Description of the Reference Symbols]
For example, the present invention can also be applied to a beam-column connection, in which protrusions are provided in a column member or a steel pipe used as a sheath pipe, the column member (joint object member) is inserted into the sheath pipe to which a beam member is connected, and concrete fills a space between the sheath pipe and the column member.
[Brief Description of the Reference Symbols]
[0079]
1 composite structure 12 protrusion 10 steel pipe pile (steel pipe) H-shaped steel (joint object member) 11 inner circumferential surface of steel pipe pile (steel pipe) concrete 15 13 buckled portion L extension length Al protrusion region A2 flat region B1 stiffening region 20 B2 raw pipe region W circumferential direction X radial direction Y pipe axis direction
1 composite structure 12 protrusion 10 steel pipe pile (steel pipe) H-shaped steel (joint object member) 11 inner circumferential surface of steel pipe pile (steel pipe) concrete 15 13 buckled portion L extension length Al protrusion region A2 flat region B1 stiffening region 20 B2 raw pipe region W circumferential direction X radial direction Y pipe axis direction
Claims (3)
1. A composite structure comprising:
a steel pipe;
a joint object member having an end portion inserted into the steel pipe; and concrete which fills a space between an inner circumferential surface of the steel pipe and the end portion of the joint object member, wherein the steel pipe includes protrusions which protrude inward in a radial direction of the steel pipe from the inner circumferential surface of the steel pipe and extend in a spiral shape along a pipe axis direction of the steel pipe, when a region in which the concrete comes into contact with the inner circumferential surface of the steel pipe is defined as a stiffening region and a region in which the concrete does not come into contact with the inner circumferential surface of the steel pipe is defined as a raw pipe region, the protrusions extend in the spiral shape along the pipe axis direction to straddle a boundary between the stiffening region and the raw pipe region, an extension length of the protrusion in the pipe axis direction in the raw pipe region is equal to or greater than a local buckling half-wavelength of the steel pipe, and when the local buckling half-wavelength of the steel pipe is defined as .lambda. (mm), an outer diameter of the steel pipe is defined as D (mm), and a plate thickness of the steel pipe is defined as t (mm), the local buckling half-wavelength .lambda. is expressed in the following Expression (1), and a ratio D/t obtained by dividing the outer diameter D by the plate thickness t of the steel pipe is 50 or higher and 100 or lower.
a steel pipe;
a joint object member having an end portion inserted into the steel pipe; and concrete which fills a space between an inner circumferential surface of the steel pipe and the end portion of the joint object member, wherein the steel pipe includes protrusions which protrude inward in a radial direction of the steel pipe from the inner circumferential surface of the steel pipe and extend in a spiral shape along a pipe axis direction of the steel pipe, when a region in which the concrete comes into contact with the inner circumferential surface of the steel pipe is defined as a stiffening region and a region in which the concrete does not come into contact with the inner circumferential surface of the steel pipe is defined as a raw pipe region, the protrusions extend in the spiral shape along the pipe axis direction to straddle a boundary between the stiffening region and the raw pipe region, an extension length of the protrusion in the pipe axis direction in the raw pipe region is equal to or greater than a local buckling half-wavelength of the steel pipe, and when the local buckling half-wavelength of the steel pipe is defined as .lambda. (mm), an outer diameter of the steel pipe is defined as D (mm), and a plate thickness of the steel pipe is defined as t (mm), the local buckling half-wavelength .lambda. is expressed in the following Expression (1), and a ratio D/t obtained by dividing the outer diameter D by the plate thickness t of the steel pipe is 50 or higher and 100 or lower.
2. The composite structure according to claim 1, wherein, when the protrusion is viewed from the inside in the radial direction of the steel pipe, an angle between a circumferential direction of the steel pipe and the protrusion is 30° or higher and lower than 90°.
3. The composite structure according to claim 1 or 2, wherein, when the steel pipe is viewed in a section parallel to the pipe axis direction, convex sections of the protrusions are arranged with an interval equal to or smaller than the local buckling half-wavelength .lambda. therebetween along the pipe axis direction.
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| JP2013-197688 | 2013-09-25 | ||
| PCT/JP2014/073921 WO2015045872A1 (en) | 2013-09-25 | 2014-09-10 | Composite structure |
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| JP6575422B2 (en) * | 2016-04-11 | 2019-09-18 | Ｊｆｅエンジニアリング株式会社 | Jacket structure |
| CN109404224A (en) * | 2018-12-10 | 2019-03-01 | 重庆大学 | It is a kind of based on edge put more energy into combined shell wind-powered electricity generation mix tower |
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| JP2000220139A (en) * | 1999-02-03 | 2000-08-08 | Nippon Steel Corp | Steel pipe pile for inner digging |
| JP3690496B2 (en) * | 2000-11-06 | 2005-08-31 | 清水建設株式会社 | Foundation structure of building and construction method of foundation |
| JP2006292088A (en) * | 2005-04-12 | 2006-10-26 | Nippon Steel Corp | Steel pipe having superior pipe end buckling deformation-proof property |
| JP2009197472A (en) * | 2008-02-21 | 2009-09-03 | Nippon Steel Corp | Steel pipe pile and foundation structure |
| JP2011144562A (en) * | 2010-01-15 | 2011-07-28 | Nippon Steel Engineering Co Ltd | Steel pipe, steel pipe pile, and manufacturing method for steel pipe |
-
2014
- 2014-09-10 CA CA2920289A patent/CA2920289C/en active Active
- 2014-09-10 JP JP2015539092A patent/JP6386462B2/en not_active Expired - Fee Related
- 2014-09-10 WO PCT/JP2014/073921 patent/WO2015045872A1/en active Application Filing
- 2014-09-10 AU AU2014325437A patent/AU2014325437B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| AU2014325437A1 (en) | 2016-01-07 |
| WO2015045872A1 (en) | 2015-04-02 |
| JPWO2015045872A1 (en) | 2017-03-09 |
| JP6386462B2 (en) | 2018-09-05 |
| AU2014325437B2 (en) | 2016-10-13 |
| CA2920289C (en) | 2018-05-01 |
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