Method for evaluating the seismic performance of steel pipe piles, and calculation program.

Abstract

This system allows for a simple evaluation of the seismic performance of steel pipe piles in the soil up to their ultimate state when the pile heads are rotatably free-jointed or rotatably semi-rigid-jointed, and enables quick responses to numerous specification changes. [Solution] A method for evaluating the seismic performance of steel pipe piles up to the ultimate state in the soil, which involves multiplying the standardized diameter-to-thickness ratio of the steel pipe pile by an index (1) composed of the pile's characteristic values, and provides a method for evaluating the seismic performance of steel pipe piles where the pile head is a rotationally free joint or a rotationally semi-rigid joint. Here, in index (1), β (upper bar) is the dimensionless characteristic value of the pile (dimensionless in units of m), D is the outer diameter of the steel pipe pile, t is the plate thickness of the steel pipe pile, σ y E is the yield point of the steel pipe pile. p is the Young's modulus of the steel pipe pile, and a and b are constants. [Mathematics 1] TIFF2026113043000028.tif17170

Description

Technical Field

[0001] The present invention relates to a method for evaluating the seismic performance of steel pipe piles and a calculation program.

Background Art

[0002] Steel pipe piles are used as foundation piles for civil engineering structures and building structures. In view of the recent intensification of earthquakes and the damage to foundation piles caused by past earthquakes, the need to handle the seismic performance of steel pipe piles up to the ultimate state in practical design has been increasing, and a simple and predictable evaluation method is required.

[0003] Conventionally, it is known that the seismic performance of steel pipe piles up to the ultimate state in the air can be easily evaluated by the deformation performance according to the reference formula (1) shown in, for example, Non-Patent Document 1 and the bearing capacity performance according to the reference formula (2). That is, in Non-Patent Document 1, the seismic performance of steel pipe piles up to the ultimate state in the air is expressed by a mathematical formula using the parameters of the steel material. Here, in the reference formulas (1) and (2), θ ,

[0005] , , , : the rotation angle (rad) when the bearing capacity decreases to 95% of the maximum bearing capacity after the maximum bearing capacity, θ pc : the elastic limit rotation amount (rad), H max : the maximum horizontal bearing capacity (kN), H al : the short-term allowable horizontal force (kN), D: the outer diameter (mm) of the steel pipe pile, t: the plate thickness (mm), σ y : the yield point of the pile (N / mm 2 )、E p : the Young's modulus of the pile (N / mm 2 ), (D / t) × (σ y / E p ): is the normalized diameter-thickness ratio.

[0004]

Number

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] However, the conventional method for evaluating the seismic performance of steel pipe piles, as shown in Non-Patent Document 1 mentioned above, had the following problems. Non-patent document 1 mentioned above describes an evaluation method that uses an evaluation formula to express the seismic performance of steel pipe piles in air up to their ultimate state using steel material parameters, and does not apply to evaluation in soil. In other words, when evaluating the seismic performance of steel pipe piles as pile foundations, it is necessary to consider the case where the pile head is subjected to horizontal force (earthquake force) in the soil, which is the actual usage environment for steel pipe piles. Unlike in the air, steel pipe piles and the ground exhibit complex behavior in the soil, where they mechanically interact with each other. This has led to the problem that, conventionally, the seismic performance of steel pipe piles up to their ultimate state can only be predicted through experiments or detailed numerical analysis. Such experimental and detailed numerical analysis methods make it difficult to quickly respond to numerous specification changes in practical design. Therefore, there is a need for a simple evaluation method that can predict the seismic performance of steel pipe piles up to their ultimate state according to the specifications of the pile and the ground.

[0007] Furthermore, conventionally, it is common to design with a fixed pile head condition that completely restrains the rotation of the pile head. However, in recent practical designs, in order to reduce the stress generated at the pile head during major earthquakes and to design rationally, there is a growing trend to adopt a free pile head condition that does not restrain the rotation of the pile head, or a semi-rigid pile head condition that partially restrains the rotation of the pile head. Therefore, there is a need for an appropriate evaluation method when such a rotationally free connection that realizes the free pile head condition or a rotationally semi-rigid connection that realizes the semi-rigid pile head condition is adopted at the pile head.

[0008] This invention has been made in view of the above-mentioned problems, and aims to provide a method for evaluating the seismic performance of steel pipe piles and a calculation program that can predict the seismic performance of steel pipe piles up to the ultimate state in the soil when the pile head of the steel pipe pile is rotatably free-jointed or rotatably semi-rigid-jointed, using a simple index determined from the specifications of the pile and the ground, and that can quickly respond to numerous specification changes. [Means for solving the problem]

[0009] (1) Embodiment 1 of the method for evaluating the seismic performance of a steel pipe pile according to the present invention is a method for evaluating the seismic performance of a steel pipe pile up to the ultimate state in the soil, characterized in that it uses an index (1) which is composed of the standardized diameter-to-thickness ratio of the steel pipe pile and the characteristic value of the pile, and the pile head of the steel pipe pile is rotatably free-jointed or rotatably semi-rigid-jointed. Here, in index (1), β (upper bar) is the dimensionless characteristic value of the pile (dimensionless in units of m), D is the outer diameter of the steel pipe pile, t is the plate thickness of the steel pipe pile, σ y The yield point of the steel pipe pile is E p is the Young's modulus of the steel pipe pile, and a and b are constants.

[0010]

number

[0011] (2) Aspect 2 of the present invention is a method for evaluating the seismic performance of a steel pipe pile according to aspect 1, wherein the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1. Here, in the case of the pile head free condition where there is no rotational restraint of the pile head, f = 0, and the closer f approaches 1, the greater the rotational restraint.

[0012] (3) Aspect 3 of the present invention may be characterized in that, in the method for evaluating the seismic performance of a steel pipe pile according to aspect 1 or aspect 2, the deformation performance μ of the steel pipe pile up to the ultimate state defined by formula (2) is evaluated, and formula (3) is used using the index (1) and formula (2). Here, δ u δ is the horizontal displacement of the pile head in the ultimate state.y is the horizontal displacement of the pile head at the time of pile yielding, and c, d, and e are constants.

[0013]

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[0014] (4) Aspect 4 of the present invention is a method for evaluating the seismic performance of steel pipe piles according to aspect 3, wherein in formula (3), it is preferable that the constant a satisfies the range of -3 ≤ a ≤ 1, and the constant b satisfies the range of 0.5 ≤ b ≤ 3.5.

[0015] (5) Aspect 5 of the present invention is a method for evaluating the seismic performance of a steel pipe pile according to aspect 3 or aspect 4, wherein the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1, and in formula (3), the constant c satisfies the range of 0.61 + 0.19f ≤ c ≤ 1.03 - 0.06f, the constant d satisfies the range of -0.36 + 0.15f ≤ d ≤ -0.22 + 0.06f, and the constant e satisfies the range of -0.7 + 0.5f ≤ e ≤ 0.7 - 0.5f. Here, in the degree of fixedness of the pile head f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f=0, and the closer f approaches 1, the greater the constraint on rotation.

[0016] (6) Aspect 6 of the present invention may be characterized in that, in the method for evaluating the seismic performance of a steel pipe pile according to aspect 1 or aspect 2, the load-bearing capacity λ of the steel pipe pile up to the ultimate state defined by formula (4) is evaluated, and formula (5) is used using the index (1) and formula (4). Here, P u P is the horizontal load-bearing capacity in the ultimate state. y is the horizontal load-bearing capacity at the time of pile yielding, and c, d, and e are constants.

[0017]

number

[0018] (7) Aspect 7 of the present invention is a method for evaluating the seismic performance of steel pipe piles according to aspect 6, wherein in formula (5), it is preferable that the constant a satisfies the range of -1 ≤ a ≤ 3, and the constant b satisfies the range of 0.5 ≤ b ≤ 3.5.

[0019] (8) Aspect 8 of the present invention is a method for evaluating the seismic performance of a steel pipe pile according to aspect 6 or aspect 7, wherein the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1, and in formula (5), the constant c satisfies the range of 1.02 - 0.1f ≤ c ≤ 1.10 - 0.03f, the constant d satisfies the range of -0.03 - 0.03f ≤ d ≤ -0.01 - 0.02f, and the constant e satisfies the range of -0.05 - 0.01f ≤ e ≤ 0.05 + 0.01f. Here, in the case of the pile head free condition where there is no rotational restraint of the pile head, f = 0, and the closer f approaches 1, the greater the rotational restraint.

[0020] (9) Aspect 9 of the present invention is a method for evaluating the seismic performance of a steel pipe pile according to aspect 1 or aspect 2, wherein the energy absorption share ratio E up to the ultimate state of the steel pipe pile is expressed using formula (6) which uses the index (1). pile It may also be characterized by evaluating , where c, d, and e are constants.

[0021]

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[0022] (10) Aspect 10 of the present invention is a method for evaluating the seismic performance of steel pipe piles according to aspect 9, wherein in formula (6), the constant a satisfies the range -3 ≤ a ≤ 1, and the constant b satisfies the range 0.5 ≤ b ≤ 3.5.

[0023] (11) Aspect 11 of the present invention is a method for evaluating the seismic performance of a steel pipe pile according to aspect 9 or aspect 10, wherein the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1, and in formula (6), the constant c satisfies the range of 37.97 - 8.50f ≤ c ≤ 44.89 - 10.16f, the constant d satisfies the range of -0.09 - 0.01f ≤ d ≤ -0.05 - 0.01f, and the constant e satisfies the range of -6.0 + 1.5f ≤ e ≤ 6.0 - 1.5f. Here, in the case of the pile head free condition where there is no rotational restraint of the pile head, f = 0, and the closer f approaches 1, the greater the rotational restraint.

[0024] (12) Embodiment 12 of the calculation program according to the present invention is a calculation program that performs the seismic performance evaluation method of steel pipe piles according to Embodiment 1 on a computer, wherein the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ y Young's modulus E p The method is characterized by performing the steps of: calculating the index (1) using the formula (2); evaluating the deformation performance μ of the steel pipe pile up to the ultimate state as defined by formula (2); and evaluating the seismic performance of the steel pipe pile up to the ultimate state, where the pile head of the steel pipe pile is either freely rotated or semi-rigidly rotated, based on a calculation formula using formula (3) which uses the index (1) and formula (2); and ensuring that the degree of fixedness f of the pile head, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1. Here, δ u δ is the horizontal displacement of the pile head in the ultimate state. y is the horizontal displacement of the pile head at the time of pile yielding, c, d, and e are constants, and in the case of a pile head free condition where there is no constraint on the rotation of the pile head at the degree of pile head fixation f, f=0, and the closer f approaches 1, the greater the constraint on rotation.

[0025] (13) Embodiment 13 of the calculation program according to the present invention is a calculation program that performs the seismic performance evaluation method of steel pipe piles according to Embodiment 1 on a computer, wherein the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ y Young's modulus E pThe method is characterized by performing the steps of: calculating the index (1) using the formula (2); evaluating the deformation performance μ of the steel pipe pile up to the ultimate state as defined by formula (2); and evaluating the seismic performance of the steel pipe pile up to the ultimate state, where the pile head of the steel pipe pile is either freely rotated or semi-rigidly rotated, based on a calculation formula using formula (3) which uses the index (1) and formula (2). Here, δ u δ is the horizontal displacement of the pile head in the ultimate state. y is the horizontal displacement of the pile head at the time of pile yielding, and c, d, and e are constants.

[0026] (14) Aspect 14 of the present invention is an arithmetic program of aspect 12 or aspect 13, in formula (3), it is preferable that the constant a satisfies the range -3 ≤ a ≤ 1, and the constant b satisfies the range 0.5 ≤ b ≤ 3.5.

[0027] (15) Embodiment 15 of the present invention may be characterized in that, in the calculation program of Embodiment 14, the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1, and in formula (3), the constant c satisfies the range of 0.61 + 0.19f ≤ c ≤ 1.03 - 0.06f, the constant d satisfies the range of -0.36 + 0.15f ≤ d ≤ -0.22 + 0.06f, and the constant e satisfies the range of -0.7 + 0.5f ≤ e ≤ 0.7 - 0.5f. Here, in the case of the pile head free condition where there is no constraint on the rotation of the pile head, the degree of fixedness of the pile head f is f=0, and the closer f approaches 1, the greater the constraint on rotation.

[0028] (16) Embodiment 16 of the calculation program according to the present invention is a calculation program that performs the seismic performance evaluation method of steel pipe piles according to Embodiment 1 on a computer, wherein the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ y Young's modulus E pThe method is characterized by performing the steps of: calculating the index (1) using the formula; evaluating the load-bearing capacity λ of the steel pipe pile up to the ultimate state as defined by formula (4); and evaluating the seismic performance up to the ultimate state of the steel pipe pile, in which the pile head is either freely rotated or semi-rigidly rotated, based on a calculation formula using formula (5) which uses the index (1) and formula (4), wherein the pile head fixation degree f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1. Here, P u P is the horizontal load-bearing capacity in the ultimate state. y is the horizontal load-bearing capacity at the time of pile yielding, c, d, and e are constants, and in the case of a pile head free condition where there is no constraint on the rotation of the pile head at the degree of pile head fixation f, f=0, and the closer f approaches 1, the greater the constraint on rotation.

[0029] (17) Embodiment 17 of the calculation program according to the present invention is a calculation program that performs the method for evaluating the seismic performance of a steel pipe pile according to Embodiment 1 on a computer, characterized in that it performs the steps of: calculating the index (1) using the characteristic value β (upper bar) of the pile, the outer diameter D of the steel pipe pile, the plate thickness t, the yield point σy, and the Young's modulus Ep; and evaluating the load-bearing capacity λ of the steel pipe pile up to the ultimate state as defined by formula (4), and evaluating the seismic performance of the steel pipe pile up to the ultimate state in which the pile head of the steel pipe pile is a rotationally free joint or a rotationally semi-rigid joint, based on a calculation formula using formula (5) which uses the index (1) and formula (4). Here, Pu is the horizontal load-bearing capacity in the ultimate state, Py is the horizontal load-bearing capacity at the time of pile yielding, and c, d, and e are constants.

[0030] (18) Aspect 18 of the present invention is a calculation program of aspect 16 or aspect 17, in which, in formula (5), it is preferable that the constant a satisfies the range -1 ≤ a ≤ 3 and the constant b satisfies the range 0.5 ≤ b ≤ 3.5.

[0031] (19) Aspect 19 of the present invention may be characterized in that, in the calculation program of aspect 18, the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1, and in formula (5), the constant c satisfies the range of 1.02 - 0.1f ≤ c ≤ 1.10 - 0.03f, the constant d satisfies the range of -0.03 - 0.03f ≤ d ≤ -0.01 - 0.02f, and the constant e satisfies the range of -0.05 - 0.01f ≤ e ≤ 0.05 + 0.01f. Here, in the case of the pile head free condition where there is no constraint on the rotation of the pile head, the degree of fixedness of the pile head f is f=0, and the closer f approaches 1, the greater the constraint on rotation.

[0032] (20) Embodiment 20 of the calculation program according to the present invention is a calculation program that performs the seismic performance evaluation method of steel pipe piles according to Embodiment 1 on a computer, wherein the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ y Young's modulus E p The steps of calculating the index (1) using and the energy absorption share E of the steel pipe pile up to the ultimate state using formula (6) with the index (1) pile The method involves evaluating the seismic performance of a steel pipe pile up to its ultimate state, where the pile head of the steel pipe pile is either freely rotated or semi-rigidly rotated, and is characterized in that the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1. Here, c, d, and e are constants, and in the case of the pile head free condition where there is no constraint on the rotation of the pile head at the degree of pile head fixation f, f=0, and the closer f approaches 1, the greater the constraint on rotation.

[0033] (21) Embodiment 21 of the calculation program according to the present invention is a calculation program that performs the seismic performance evaluation method of steel pipe piles according to Embodiment 1 on a computer, wherein the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ y Young's modulus E p The steps of calculating the index (1) using and the energy absorption share E of the steel pipe pile up to the ultimate state using formula (6) with the index (1) pileThe method is characterized by the steps of evaluating the seismic performance of steel pipe piles up to the ultimate state, where the pile head of the steel pipe pile is either freely rotatably connected or semi-rigidly rotatably connected. Here, c, d, and e are constants.

[0034] (22) Aspect 22 of the present invention is a calculation program of aspect 20 or aspect 21 in which, in formula (6), it is preferable that the constant a satisfies the range -3 ≤ a ≤ 1 and the constant b satisfies the range 0.5 ≤ b ≤ 3.5.

[0035] (23) Aspect 23 of the present invention may be characterized in that, in the calculation program of aspect 22, the degree of fixedness of the pile head f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, satisfies the range of 0 ≤ f < 1, and in formula (6), the constant c satisfies the range of 37.97 - 8.50f ≤ c ≤ 44.89 - 10.16f, the constant d satisfies the range of -0.09 - 0.01f ≤ d ≤ -0.05 - 0.01f, and the constant e satisfies the range of -6.0 + 1.5f ≤ e ≤ 6.0 - 1.5f. Here, in the case of the pile head free condition where there is no constraint on the rotation of the pile head, the degree of fixedness of the pile head f is f=0, and the closer f approaches 1, the greater the constraint on rotation. [Effects of the Invention]

[0036] According to the seismic performance evaluation method and calculation program of the present invention, the seismic performance of a steel pipe pile up to its ultimate state in the soil when the pile head of the steel pipe pile is rotatably free-jointed or rotatably semi-rigid-jointed can be easily predicted, and it is possible to respond quickly to numerous specification changes. [Brief explanation of the drawing]

[0037] [Figure 1] This figure shows the analytical model used for the analysis to set the evaluation values ​​of the embodiment of the present invention. [Figure 2] This figure shows the evaluation and analysis values ​​for deformation performance according to this embodiment. [Figure 3] This figure shows the evaluation and analysis values ​​for load-bearing capacity according to this embodiment. [Figure 4] This figure shows the evaluation and analysis values ​​for the energy absorption contribution ratio of steel pipe piles according to this embodiment. [Figure 5] This figure shows the deformation performance when evaluated using only the conventional steel material index. [Figure 6] This diagram shows the evaluation of load-bearing capacity using only the conventional steel material index. [Figure 7] This figure shows the energy absorption contribution ratio of steel pipe piles when evaluated using a conventional index that only considers steel materials. [Modes for carrying out the invention]

[0038] The following describes, with reference to the drawings, a method for evaluating the seismic performance of steel pipe piles according to embodiments of the present invention, and a calculation program.

[0039] The method for evaluating the seismic performance of steel pipe piles according to this embodiment involves expressing the seismic performance of the steel pipe pile up to its ultimate state in the soil using a mathematical formula (evaluation formula), and then using this evaluation formula to evaluate the seismic performance.

[0040] Here, the "ultimate state" is defined as the state in which the steel pipe pile begins to lose the ability to support the superstructure due to local buckling. Specifically, it is the lower limit of the steel pipe strain at maximum load in the results of buckling experiments on circular steel pipes subjected to compressive axial force and short column compression experiments on spiral steel pipes, as described in Non-Patent Literature 2 ("Guidelines for the Design of Building Foundation Structures, 2019," Architectural Institute of Japan), and is the limit strain ε, which is considered to be a conservative estimate of the strain at which local buckling occurs. u The ultimate state is defined as the point at which the strain occurs at the outer edge of the steel pipe pile. The limiting strain ε is also defined. u This can be expressed by formula (7), which uses the outer diameter D (mm) and plate thickness t (mm) of the steel pipe pile.

[0041]

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[0042] (index) Since steel pipe piles and the ground interact mechanically in a complex manner underground, it is effective to appropriately consider the characteristics of the ground in addition to the characteristics of the steel pipe pile when evaluating the seismic performance of steel pipe piles up to their ultimate state. The method for evaluating the seismic performance of steel pipe piles according to this embodiment uses an index (1) that incorporates the standardized diameter-to-thickness ratio (formula (8)), which is a parameter representing the characteristics of the steel pipe pile, and the pile characteristic value β (upper bar), which is a parameter (formula (9)) that takes into account the characteristics of both the steel pipe pile and the ground, by exponential calculation.

[0043] In this case, the pile head of the steel pipe pile is required to be either freely rotated or semi-rigidly rotated. Specifically, the pile head fixation degree f, which indicates the degree of rotational restraint of the pile head of the steel pipe pile, must satisfy the range 0 ≤ f < 1. That is, the pile head fixation degree f (0 ≤ f < 1) is considered because the seismic performance of the steel pipe pile up to its ultimate state in the soil changes depending on the pile head fixation degree f. In the case of a free pile head with no rotational restraint of the pile head, f = 0, and the closer f approaches 1, the greater the rotational restraint. Here, the pile head fixation degree f is defined as M / M0, which is the ratio of the pile head bending moment M to the pile head bending moment M0 that occurs when the rotation of the pile head is completely restrained.

[0044] Here, in index (1), β (upper bar) is the dimensionless characteristic value of the pile (dimensionless in units of m), σ y The yield point (N / mm²) of steel pipe piles is the yield point (N / mm²) 2 ), E p The Young's modulus (N / mm²) of steel pipe piles is 2 ), k h The horizontal ground reaction coefficient (N / mm²) 3 ), I p This is the second moment of area (mm) of the steel pipe pile. 4 ), a and b are constants.

[0045]

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[0046]

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[0047] The horizontal ground reaction coefficient k that constitutes β (upper bar) h In calculating this, publicly known methods can be used. For example, the Architectural Institute of Japan's "Guidelines for the Design of Building Foundation Structures" (Architectural Institute of Japan: Guidelines for the Design of Building Foundation Structures, pp. 178-283, 2019), the Japan Road Association's "Specifications for Road Bridges and Commentary IV: Substructures" (Japan Road Association: Specifications for Road Bridges and Commentary IV: Substructures, pp. 226-316, 2017), the Railway Technical Research Institute's "Design Standards for Railway Structures and Others: Foundation Structures" (Railway Technical Research Institute: Design Standards for Railway Structures and Others: Foundation Structures, pp. 247-330, 2012), the Japan Port and Harbor Association's "Technical Standards for Port Facilities and Others (Volume 2)" (Japan Port and Harbor Association: Technical Standards for Port Facilities and Others (Volume 2), pp. 675-744, 2018), and Francis's formula (Francis, AJ: Analysis of Examples include "Pile Groups with Flexural Resistance," Journal of the Soil Mechanics and Foundations Division, ASCE, Vol.90, Issue 3, pp.10-32, 1964; the Kishida-Nakai method (Hideaki Kishida, Shoichi Nakai: Horizontal Resistance of Piles Considering Soil Failure, Transactions of the Architectural Institute of Japan, No. 281, pp.41-55, 1979.7); and methods presented by various organizations (Ministry of Land, Infrastructure, Transport and Tourism, Japan Society of Civil Engineers, Japanese Geotechnical Society, etc.).

[0048] [Example of calculation method: Kishida-Nakai method] Horizontal ground reaction coefficient k h As an example of how to calculate it, using the calculation method of Kishida and Nakai (Hideaki Kishida, Shoichi Nakai: Horizontal resistance of piles considering ground failure, Transactions of the Architectural Institute of Japan, No. 281, pp. 41-55, 1979.7), it can be calculated as follows.

[0049] Horizontal ground reaction coefficient k h The deformation modulus E of the ground is given by equation (10) proposed by Francis. sThis is evaluated using formula (11).

[0050]

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[0051] Here, k h : Horizontal ground reaction coefficient (kN / m 3 ), E s : Modulus of deformation of the ground (kN / m 2 ), D: Outer diameter of steel pipe pile (m), N: N-value of the ground, E p : Young's modulus of steel pipe piles (kN / m 2 ), I p : Second moment of area of ​​steel pipe pile (m 4 ), ν: Poisson's ratio of the ground.

[0052] [Example of calculation method: Method from the Building Foundation Structure Design Guidelines] Furthermore, using the calculation method outlined in the above-mentioned building foundation structure design guidelines, the calculation can be performed as follows.

[0053] Horizontal ground reaction coefficient k h The deformation coefficient E of the ground is given by equations (12), (13), and (14). s This is evaluated using formula (15).

[0054]

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[0055] Here, k h0 : Reference horizontal ground reaction coefficient (kN / m 3 ), k h : Horizontal ground reaction coefficient (kN / m 3 ), E s : Modulus of deformation of the ground (kN / m 2 ), D: outer diameter of the steel pipe pile (m), D0: standard value of the outer diameter of the steel pipe pile (=0.01m), y: horizontal displacement of the pile (m), y0: standard horizontal displacement of the pile (=0.01m), N: N value of the ground.

[0056] This makes it possible to appropriately evaluate the mechanical influence between the steel pipe pile and the ground. Furthermore, the seismic performance of the steel pipe pile up to the ultimate state in the soil when the pile head fixation degree is less than 1, using a formula based on a very simple index (1), is calculated (deformation performance μ, bearing capacity λ, and energy absorption sharing ratio E of the steel pipe pile, as described later). pile This is an evaluation method that enables prediction of ).

[0057] (Deformation performance μ in the final state) Of the seismic performance of steel pipe piles in the soil up to the ultimate state, the deformation performance μ at the ultimate state can be defined by equation (2), and can be easily predicted by equation (3) (hereinafter referred to as evaluation equation (3)) using equation (2) and the index (1) mentioned above. Here, δ u The ultimate state pile head horizontal displacement (mm), δ y is the horizontal displacement of the pile head at the time of pile yielding (mm), and c, d, and e are constants.

[0058]

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[0059] By satisfying the ranges -3≦a≦1, 0.5≦b≦3.5, 0.61+0.19f≦c≦1.03-0.06f, -0.36+0.15f≦d≦-0.22+0.06f, -0.7+0.5f≦e≦0.7-0.5f, and 0≦f≦1 for each constant a, b, c, d, and e in evaluation formula (3), the deformation performance μ in the ultimate state can be appropriately evaluated even when there are other influences such as uncertainty in the ground and construction errors. f is the degree of pile head fixation as described above. In evaluation formula (3), it is most preferable that a = -1 and b = 2.

[0060] (Ultimate state yield strength λ) Of the seismic performance of steel pipe piles in the soil up to the ultimate state, the ultimate state bearing capacity λ can be defined by equation (4), and can be easily predicted by equation (5) (hereinafter referred to as evaluation equation (5)) using equation (4) and the index (1) mentioned above. Here, P uThe ultimate horizontal load-bearing capacity (kN), P y is the horizontal load-bearing capacity (kN) at the time of pile yielding, and c, d, and e are constants.

[0061]

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[0062] In evaluation formula (5), if each constant a, b, c, d, and e satisfies the ranges -1≦a≦3, 0.5≦b≦3.5, 1.02-0.1f≦c≦1.10-0.03f, -0.03-0.03f≦d≦-0.01-0.02f, -0.05-0.01f≦e≦0.05+0.01f, and 0≦f≦1, respectively, the ultimate bearing capacity performance λ can be appropriately evaluated even when there are other influences such as uncertainty in the ground and construction errors. f is the degree of pile head fixation as described above. In evaluation formula (5), it is most preferable that a=1 and b=2.

[0063] (Energy absorption share of steel pipe piles in the final state E) pile ) In the soil, seismic energy is absorbed by both the steel pipe piles and the ground, but the proportion of energy absorption by the steel pipe piles in the ultimate state of seismic performance up to the ultimate state in the soil is E. pile The percentage of energy absorption by steel pipe piles (total energy absorption by steel pipe piles and energy absorption by the ground) can be easily predicted using formula (6) (hereinafter referred to as evaluation formula (6)) which uses the above index (1). Here, c, d, and e are constants.

[0064]

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[0065] For each constant a, b, c, d, and e in evaluation formula (6), the ranges -3≦a≦1, 0.5≦b≦3.5, 37.97-8.50f≦c≦44.89-10.16f, -0.09-0.01f≦d≦-0.05-0.01f, -6.0+1.5f≦e≦6.0-1.5f, and 0≦f≦1 are satisfied, respectively, so that even when there are other influences such as uncertainty in the ground and construction errors, the energy absorption share ratio E of the steel pipe pile in the ultimate state is satisfied. pile This allows for appropriate evaluation. f is the degree of pile head fixation as described above. In evaluation formula (6), it is most preferable that a = -1 and b = 2.

[0066] The method for evaluating the seismic performance of steel pipe piles described above may be performed on a computer using a calculation program. Specifically, the calculation program uses the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. y Young's modulus E p The procedure involves the steps of calculating the aforementioned index (1) using the formula (2) to evaluate the seismic performance of the steel pipe pile based on one or more formulas (2) to (6).

[0067] The above-described method for evaluating the seismic performance of steel pipe piles and the calculation program use an effective index (1) that appropriately considers the characteristics of the ground in addition to the characteristics of the steel pipe pile, i.e., an effective index (1) expressed mathematically using parameters of the steel material and the ground. Therefore, it is possible to accurately and quickly predict the seismic performance of steel pipe piles up to their ultimate state in the soil, which is the actual usage environment, when the pile head of the steel pipe pile is a rotationally free joint or a rotationally semi-rigid joint.

[0068] Then, using a simple index (1) determined from the specifications of the steel pipe pile and the ground, evaluation formulas (3), (5), and (6) were used to determine the coefficients considering the pile head fixation degree f, and the deformation performance μ, bearing capacity λ, and energy absorption sharing ratio E of the steel pipe pile up to the ultimate state of the steel pipe pile in the soil when the pile head fixation degree f is less than 1 were determined. pileThis allows for easy prediction. In practical design that considers the seismic performance of steel pipe piles up to their ultimate state, the evaluation method of this embodiment can be used to quickly respond to numerous specification changes.

[0069] Next, we will explain in more detail each evaluation formula in the method for evaluating the seismic performance of the steel pipe piles in the embodiment described above. Specifically, by performing the following analysis, the parameters that represent the characteristics of the steel pipe pile, the normalized diameter-to-thickness ratio (D / t)·(σ y / E p We found that evaluation can be performed using a simple mathematical formula (evaluation formula) by incorporating the above index (1), which is a parameter that takes into account the characteristics of both the steel pipe pile and the ground, and the pile characteristic value β (upper bar), using a power calculation.

[0070] Figure 1 shows the analysis model 1 of the steel pipe pile 10 to be analyzed. The analysis was performed using analysis model 1, employing a static pushover analysis that gradually increased the horizontal displacement (arrow F shown in Figure 1) of the pile head 10a of the steel pipe pile 10. The steel pipe pile 10 was modeled using beam elements 11 (fiber model), and the ground was modeled using spring elements 12. The steel pipe pile 10 was divided into sections with nodes at 200 mm intervals in the depth direction, and ground springs 12 were connected to each node. The pile length H of the steel pipe pile 10 was set to a sufficiently long 100 m to simulate the conditions of a semi-infinite long pile. The pile head 10a was examined under both fixed pile head conditions (pile head fixation degree f=1) and free pile head conditions (pile head fixation degree f=0). The lower end of the pile 10b was defined as a boundary condition using a horizontal pin roller 13.

[0071] The relationship between horizontal ground reaction force and horizontal displacement of a ground spring, and the degree of plastic horizontal ground reaction force, are evaluated using the method proposed by Kishida and Nakai (Hideaki Kishida, Shoichi Nakai: Horizontal resistance of piles considering ground failure, Transactions of the Architectural Institute of Japan, No. 281, pp. 41-55, 1979.7). This is based on the horizontal ground reaction coefficient k, which is the initial stiffness of the horizontal ground reaction force p. hThis is given by formula (10) proposed by Francis (Francis, AJ: Analysis of Pile Groups with Flexural Resistance, Journal of the Soil Mechanics and Foundations Division, ASCE, Vol.90, Issue 3, pp.10-32, 1964), and the plastic horizontal ground reaction force p y This is a bilinear evaluation method where the point where the deformation modulus of the ground is reached is defined as the inflection point. s This is evaluated using formula (11). Plastic horizontal ground reaction force p y As shown in equation (16), the values ​​of equations (17) and (18) are compared at each depth, and the smaller value is adopted. The internal friction angle φ of the ground is evaluated using Osaki's formula shown in equation (19) (Osaki, Yoshihiko: "Tokyo Ground Map", Gihodo Publishing, pp. 18-19, 1959). The earth pressure at rest coefficient K0 is evaluated using Yerkee's formula shown in equation (20).

[0072]

number

[0073]

number

[0074]

number

[0075]

number

[0076] Here, k h : Horizontal ground reaction coefficient (kN / m 3 ), E s : Modulus of deformation of the ground (kN / m 2 ), D: Outer diameter of steel pipe pile (m), N: N-value of the ground, E p : Young's modulus of steel pipe piles (kN / m 2)、I p : Second moment of cross - section of steel pipe pile (m 4 )、ν: Poisson's ratio of soil (assumed to be 0.33 for sandy soil), p: Horizontal soil reaction (kN / m 2 )、p y : Plastic horizontal soil reaction degree (kN / m 2 )、γ’: Effective unit volume weight of soil (kN / m 3 )、z: Depth (m), K0: Coefficient of earth pressure at rest (= 1 - sinφ), K A : Coefficient of active earth pressure (=(1 - sinφ) / (1 + sinφ)), φ: Angle of internal friction (°), α, β: Wedge angles (for sandy soil, α = φ / 2, β = π / 4 + φ / 2).

[0077] Under the conditions of such an analytical model 1, for each of the pile - head fixed condition (pile - head fixation degree f = 1) and the pile - head free condition (pile - head fixation degree f = 0), 36 cases were analyzed by combining different 4 cases of the outer diameters of steel pipe piles (D = 400mm, 800mm, 1200mm, 1600mm), different 3 cases of the diameter - thickness ratios (D / t = 25, 50, 75), and different 3 cases of the soil N - values (5, 10, 15). Thus, for each of the pile - head fixed condition (pile - head fixation degree f = 1) and the pile - head free condition (pile - head fixation degree f = 0), by analyzing 36 cases, it was considered as a study to comprehensively cover the general use range of steel pipe piles. And, as a result of the analysis of 36 cases in each of such pile - head fixed condition (pile - head fixation degree f = 1) and pile - head free condition (pile - head fixation degree f = 0), the deformation performance μ, the bearing capacity performance λ, and the energy absorption sharing ratio E pile of the steel pipe pile were taken as the analytical values, and the evaluation formulas for each were obtained.

[0078] Figure 2 is a diagram showing the deformation performance μ based on the evaluation value and the analysis value according to the present embodiment. In Figure 2, the horizontal axis is the above-described index (1), and the vertical axis is the deformation performance μ. The 36 plots of "〇" shown in Figure 2 represent the analysis values of 36 cases of the pile head fixing condition (f = 1) according to the comparative example. The 36 plots of "□" shown in Figure 2 represent the analysis values of 36 cases of the pile head free condition (f = 0) according to the example. In Figure 2, the broken line curve according to the comparative example is a power type approximation formula by the least squares method for the analysis value of the pile head fixing condition (f = 1), and the deformation performance μ up to the final state of the steel pipe pile in the soil is generally uniquely evaluated by the index (1). In Figure 2, the solid line curve according to the example is a power type approximation formula by the least squares method for the analysis value of the pile head free condition (f = 0), and the deformation performance μ up to the final state of the steel pipe pile in the soil is generally uniquely evaluated by the index (1). Therefore, in the present embodiment, the approximation formula calculated in Figure 2 is used as the evaluation formula (the above evaluation formula (3)) for defining the deformation performance μ.

[0079] Figure 3 is a diagram showing the bearing capacity performance λ based on the evaluation value and the analysis value according to the present embodiment. In Figure 3, the horizontal axis is the above-described index (1), and the vertical axis is the bearing capacity performance λ. The 36 plots of "〇" shown in Figure 3 represent the analysis values of 36 cases of the pile head fixing condition (f = 1) according to the comparative example. The 36 plots of "□" shown in Figure 3 represent the analysis values of 36 cases of the pile head free condition (f = 0) according to the example. In Figure 3, the broken line curve according to the comparative example is a power type approximation formula by the least squares method for the analysis value of the pile head fixing condition (f = 1), and the bearing capacity performance λ up to the final state of the steel pipe pile in the soil is generally uniquely evaluated by the index (1). In Figure 3, the solid line curve according to the example is a power type approximation formula by the least squares method for the analysis value of the pile head free condition (f = 0), and the bearing capacity performance λ up to the final state of the steel pipe pile in the soil is generally uniquely evaluated by the index (1). Therefore, in the present embodiment, the approximation formula calculated in Figure 3 is used as the evaluation formula (the above evaluation formula (5)) for defining the bearing capacity performance λ.

[0080] Figure 4 is the energy absorption sharing ratio E of the steel pipe pile based on the evaluation value and the analysis value according to the present embodiment pileThis figure illustrates the above. In Figure 4, the horizontal axis represents the index (1) mentioned above, and the vertical axis represents the energy absorption share E of the steel pipe pile. pile (%) is used. The 36 "〇" plots in Figure 4 show the analytical values ​​for 36 cases of pile head fixed condition (f=1) according to the comparative example. The 36 "□" plots in Figure 4 show the analytical values ​​for 36 cases of pile head free condition (f=0) according to the example. In Figure 4, the dashed curve for the comparative example is a power-law approximation formula using the least squares method for the analytical values ​​of the pile head fixed condition (f=1), and index (1) represents the energy absorption share ratio of the steel pipe pile up to the ultimate state in the soil E pile This is generally evaluated uniquely. In Figure 4, the solid curve in the example is a least squares power-type approximation formula for the analytical value of the pile head free condition (f=0), and index (1) represents the energy absorption share E of the steel pipe pile up to the ultimate state of the steel pipe pile in the soil. pile This is generally evaluated uniquely. Therefore, in this embodiment, the approximate formula calculated in Figure 4 is used to express the energy absorption share ratio E of the steel pipe pile. pile This was defined as the evaluation formula (evaluation formula (6) above).

[0081] Here, the numerical ranges of the constants a, b, c, d, and e in evaluation formulas (3), (5), and (6) are defined as the range that includes the analyzed values. Furthermore, the most preferable numerical values ​​in evaluation formulas (3), (5), and (6) are defined as the values ​​that minimize the residual between the evaluated value and the analyzed value, calculated using the least squares method.

[0082] Next, an example of an implementation carried out to support the effectiveness of the method for evaluating the seismic performance of steel pipe piles according to the above-described embodiment will be explained below.

[0083] (Examples) The embodiment is an example that verifies the validity of the method for evaluating the seismic performance of the steel pipe pile in the embodiment described above. In the embodiment, the deformation performance μ, bearing capacity λ, and energy absorption sharing ratio E of the steel pipe pile are measured up to the ultimate state of the steel pipe pile in the soil. pileThe evaluation of the conventional indicator and the indicator of the embodiment (indicator (1) above) was illustrated in the diagram, and the conventional and the embodiment were evaluated separately. In this embodiment, Figures 2 to 4 described in the above-mentioned embodiment are used as the diagrams that were evaluated using the indicator of the embodiment (indicator (1) above).

[0084] Figures 5 to 7 illustrate the seismic performance of steel pipe piles in soil up to their ultimate state, as evaluated using conventional indicators. Figure 5 shows the deformation performance μ evaluated using conventional indicators for steel materials only. Figure 6 shows the load-bearing capacity λ evaluated using conventional indicators for steel materials only. Figure 7 shows the energy absorption share E of the steel pipe pile. pile This figure shows the results when evaluated using only conventional steel material indicators. Figures 5 to 7 show the normalized diameter-to-thickness ratio (D / t)·(σ) on the horizontal axis, which are parameters representing the characteristics of steel pipe piles. y / E p ) and the vertical axis in Figure 5 is the deformation performance μ, in Figure 6 is the load-bearing performance λ, and in Figure 7 is the energy absorption share E of the steel pipe pile. pile This is a diagram.

[0085] The deformation performance μ of steel pipe piles in soil up to the ultimate state is evaluated using the conventional and embodiment indices. As shown in Figure 5, when evaluated using the conventional steel material index, the influence of the ground is not taken into account, and it can be seen that the deformation performance on the vertical axis is not uniquely determined for a single value on the horizontal axis. In contrast, as shown in Figure 2, when evaluated using the index according to the embodiment (index (1) above), the deformation performance on the vertical axis is uniquely determined and corresponds to one value on the horizontal axis, thus confirming the validity of evaluation formula (3) for evaluating the deformation performance μ.

[0086] Next, the bearing capacity λ of the steel pipe piles in the soil up to the ultimate state is evaluated using the conventional and the embodiment's respective indices. As shown in Figure 6, when evaluated using the conventional steel material index, the influence of the ground is not taken into account, and it can be seen that the bearing capacity on the vertical axis is not uniquely determined for one value on the horizontal axis. In contrast, as shown in Figure 3, when evaluated using the index according to the embodiment (index (1) above), the load-bearing capacity on the vertical axis is uniquely determined and corresponds to one value on the horizontal axis, thus confirming the validity of the evaluation formula (5) for evaluating the load-bearing capacity λ.

[0087] Next, the energy absorption share E of the steel pipe pile up to the ultimate state of the steel pipe pile in the soil. pile The percentage (%) is evaluated using the indicators for both the conventional and the embodiment. As shown in Figure 7, when evaluated using the conventional steel material indicator, the influence of the ground is not taken into account, and therefore the energy absorption share of the steel pipe piles on the vertical axis cannot be uniquely determined for a single value on the horizontal axis. In contrast, as shown in Figure 4, when evaluated using the index according to the embodiment (index (1) above), the energy absorption share of the steel pipe pile on the vertical axis is uniquely determined and corresponds to one value on the horizontal axis, thus the energy absorption share of the steel pipe pile E pile The validity of evaluation formula (6) for evaluating [the subject] was confirmed.

[0088] The above describes embodiments of the method for evaluating the seismic performance of steel pipe piles and the calculation program according to the present invention. However, the present invention is not limited to the above embodiments and can be modified as appropriate without departing from the spirit of the invention. Furthermore, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention.

[0089] Regarding units, including those shown above, different unit systems are acceptable as long as they are consistent across the constituent indices. For example, regarding the unit "N / mm 2 This includes not only unit systems like "MPa" but also unifications like "mm" and "m". Furthermore, it is acceptable as long as correspondences are made not only between different indicators (for example, between "D" and "t") but also between the same indicators (between "one D" and "another D").

[0090] Furthermore, in order to realize the method for evaluating the seismic performance of the steel pipe pile up to its ultimate state according to this embodiment, a calculation program for executing the following steps S1 and S2 is supplied to a computer, and the seismic performance of the steel pipe pile up to its ultimate state can be evaluated according to the calculation program stored in the computer (CPU or MPU). Here, the calculation program uses the pile characteristic value β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. y Young's modulus E p The first step S1 is to calculate the index (1) described above using the above formula, and the second step S2 is to evaluate the seismic performance of the steel pipe pile up to the ultimate state based on one or more of the formulas (2) to (6) described above.

[0091] Furthermore, in the above case, the calculation program itself will implement the functions of this embodiment. As the transmission medium for the calculation program, a communication medium (such as a priority line like optical fiber or a wireless line) in a computer network system (such as a LAN, WAN such as the Internet, or a wireless communication network) that propagates and supplies program information as a carrier wave can be used.

[0092] Furthermore, means for supplying the above-mentioned arithmetic program to a computer, such as a storage medium storing such arithmetic program, can also be configured. As such a storage medium, various recording media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, magnetic tapes, non-volatile memory cards, and ROMs can be used.

Claims

1. A method for evaluating the seismic performance of steel pipe piles in the soil up to the ultimate state, The standardized diameter-to-thickness ratio of the steel pipe pile and an index (1) consisting of the pile's characteristic value are used by multiplying them. A method for evaluating the seismic performance of a steel pipe pile, wherein the pile head of the steel pipe pile is a freely rotating or semi-rigid rotating joint. Here, in the aforementioned index (1), β (upper bar) is the dimensionless characteristic value of the pile (dimensionless in units of meters), D is the outer diameter of the steel pipe pile, t is the plate thickness of the steel pipe pile, σ ｙ E is the yield point of the steel pipe pile. ｐ is the Young's modulus of the steel pipe pile, and a and b are constants. [Math 1]

2. The method for evaluating the seismic performance of a steel pipe pile according to claim 1, wherein the degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

3. The deformation performance μ of the steel pipe pile up to the ultimate state, as defined by formula (2), is evaluated. A method for evaluating the seismic performance of a steel pipe pile according to claim 1 or 2, wherein a formula (3) is used, which is derived from the aforementioned index (1) and formula (2). Here, δ ｕ δ is the horizontal displacement of the pile head in the ultimate state. ｙ is the horizontal displacement of the pile head at the time of pile yielding, and c, d, and e are constants. [Math 2]

4. In the above formula (3), The constant a satisfies the range -3 ≤ a ≤ 1. The method for evaluating the seismic performance of a steel pipe pile according to claim 3, wherein the constant b satisfies the range of 0.5 ≤ b ≤ 3.

5.

5. The degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. In the above formula (3), The constant c satisfies the range 0.61 + 0.19f ≤ c ≤ 1.03 - 0.06f. The constant d satisfies the range -0.36 + 0.15f ≤ d ≤ -0.22 + 0.06f. The method for evaluating the seismic performance of a steel pipe pile according to claim 4, wherein the constant e satisfies the range -0.7 + 0.5f ≤ e ≤ 0.7 - 0.5f. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

6. The load-bearing capacity λ of the steel pipe pile up to the ultimate state, as defined by formula (4), is evaluated. A method for evaluating the seismic performance of a steel pipe pile according to claim 1 or 2, wherein a formula (5) is used, which is derived from the aforementioned index (1) and formula (4). Here, P ｕ P is the horizontal load-bearing capacity in the ultimate state. ｙ is the horizontal load-bearing capacity at the time of pile yielding, and c, d, and e are constants. [Math 3]

7. In the above formula (5), The constant a satisfies the range -1 ≤ a ≤ 3. The method for evaluating the seismic performance of a steel pipe pile according to claim 6, wherein the constant b satisfies the range of 0.5 ≤ b ≤ 3.

5.

8. The degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. In the above formula (5), The constant c satisfies the range 1.02 - 0.1f ≤ c ≤ 1.10 - 0.03f. The constant d satisfies the range -0.03 - 0.03f ≤ d ≤ -0.01 - 0.02f. The method for evaluating the seismic performance of a steel pipe pile according to claim 6, wherein the constant e satisfies the range -0.05 - 0.01f ≤ e ≤ 0.05 + 0.01f. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

9. Using the formula (6) which employs the aforementioned index (1), the energy absorption share ratio E of the steel pipe pile up to its ultimate state is used. ｐｉｌｅ A method for evaluating the seismic performance of a steel pipe pile according to claim 1 or 2, which evaluates the following. Here, c, d, and e are constants. [Math 4]

10. In the above formula (6), The constant a satisfies the range -3 ≤ a ≤ 1. The method for evaluating the seismic performance of a steel pipe pile according to claim 9, wherein the constant b satisfies the range of 0.5 ≤ b ≤ 3.

5.

11. The degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. In the above formula (6), The constant c satisfies the range 37.97 - 8.50f ≤ c ≤ 44.89 - 10.16f. The constant d satisfies the range -0.09 - 0.01f ≤ d ≤ -0.05 - 0.01f. The method for evaluating the seismic performance of a steel pipe pile according to claim 9, wherein the constant e satisfies the range -6.0 + 1.5f ≤ e ≤ 6.0 - 1.5f. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

12. A computer program for performing the seismic performance evaluation method for steel pipe piles described in claim 1, The characteristic value β (with an overbar) of the pile, the outer diameter D, the plate thickness t, and the yield point σ of the steel pipe pile ｙ , and Young's modulus E ｐ calculating the index (1) using the above; The steps include: evaluating the deformation performance μ of the steel pipe pile up to the ultimate state as defined by formula (2), and evaluating the seismic performance of the steel pipe pile up to the ultimate state, where the pile head of the steel pipe pile is a rotationally free joint or a rotationally semi-rigid joint, based on a calculation formula using formula (3) which uses index (1) and formula (2); A calculation program that ensures the degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. Here, δ ｕ δ is the horizontal displacement of the pile head in the ultimate state. ｙ is the horizontal displacement of the pile head at the time of pile yielding, and c, d, and e are constants. In the case of the pile head free condition where there is no constraint on the rotation of the pile head, the degree of fixedness of the pile head f is f = 0, and the closer f approaches 1, the greater the constraint on rotation. [Math 5]

13. A computer program for performing the seismic performance evaluation method for steel pipe piles described in claim 1, The characteristic value of the pile β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. ｙ Young's modulus E ｐ A step of calculating the index (1) using, A calculation program that performs the steps of: evaluating the deformation performance μ of the steel pipe pile up to the ultimate state as defined by formula (2); and evaluating the seismic performance of the steel pipe pile up to the ultimate state, where the pile head of the steel pipe pile is a rotationally free joint or a rotationally semi-rigid joint, based on a calculation formula using formula (3) which uses index (1) and formula (2). Here, δ ｕ δ is the horizontal displacement of the pile head in the ultimate state. ｙ is the horizontal displacement of the pile head at the time of pile yielding, and c, d, and e are constants. [Math 6]

14. In the above formula (3), The constant a satisfies the range -3 ≤ a ≤ 1. The arithmetic program according to claim 12 or 13, wherein the constant b satisfies the range 0.5 ≤ b ≤ 3.

5.

15. The degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. In the above formula (3), The constant c satisfies the range 0.61 + 0.19f ≤ c ≤ 1.03 - 0.06f. The constant d satisfies the range -0.36 + 0.15f ≤ d ≤ -0.22 + 0.06f. The arithmetic program according to claim 14, wherein the constant e satisfies the range -0.7 + 0.5f ≤ e ≤ 0.7 - 0.5f. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

16. A computer program for performing the seismic performance evaluation method for steel pipe piles described in claim 1, The characteristic value of the pile β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. ｙ Young's modulus E ｐ A step of calculating the index (1) using, The steps include: evaluating the load-bearing capacity λ of the steel pipe pile up to the ultimate state as defined by formula (4), and evaluating the seismic performance up to the ultimate state of the steel pipe pile, in which the pile head is a rotationally free joint or a rotationally semi-rigid joint, based on a calculation formula using formula (5) which uses index (1) and formula (4); A calculation program that ensures the degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. Here, P ｕ P is the horizontal load-bearing capacity in the ultimate state. ｙ is the horizontal load-bearing capacity at the time of pile yielding, c, d, and e are constants. In the case of the pile head free condition where there is no constraint on the rotation of the pile head, the degree of fixedness of the pile head f is f = 0, and the closer f approaches 1, the greater the constraint on rotation. [Number 7]

17. A computer program for performing the seismic performance evaluation method for steel pipe piles described in claim 1, The characteristic value of the pile β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. ｙ Young's modulus E ｐ A step of calculating the index (1) using, A calculation program that performs the steps of: evaluating the load-bearing capacity λ of the steel pipe pile up to the ultimate state as defined by formula (4); and evaluating the seismic performance of the steel pipe pile up to the ultimate state, where the pile head of the steel pipe pile is a rotationally free joint or a rotationally semi-rigid joint, based on a calculation formula using formula (5) which uses index (1) and formula (4). Here, P ｕ P is the horizontal load-bearing capacity in the ultimate state. ｙ is the horizontal load-bearing capacity at the time of pile yielding, and c, d, and e are constants. [Number 8]

18. In the above formula (5), The constant a satisfies the range -1 ≤ a ≤ 3. The arithmetic program according to claim 16 or 17, wherein the constant b satisfies the range 0.5 ≤ b ≤ 3.

5.

19. The degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. In the above formula (5), The constant c satisfies the range 1.02 - 0.1f ≤ c ≤ 1.10 - 0.03f. The constant d satisfies the range -0.03 - 0.03f ≤ d ≤ -0.01 - 0.02f. The arithmetic program according to claim 18, wherein the constant e satisfies the range -0.05 - 0.01f ≤ e ≤ 0.05 + 0.01f. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

20. A computer program for performing the seismic performance evaluation method for steel pipe piles described in claim 1, The characteristic value of the pile β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. ｙ Young's modulus E ｐ A step of calculating the index (1) using, Using the formula (6) which employs the aforementioned index (1), the energy absorption share ratio E of the steel pipe pile up to its ultimate state is used. ｐｉｌｅ The steps include evaluating the seismic performance of the steel pipe pile up to the ultimate state, where the pile head of the steel pipe pile is a rotationally free joint or a rotationally semi-rigid joint, and performing the following steps: A calculation program that ensures the degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. Here, c, d, and e are constants. In the case of the pile head free condition where there is no constraint on the rotation of the pile head, the degree of fixedness of the pile head f is f = 0, and the closer f approaches 1, the greater the constraint on rotation. [Number 9]

21. A computer program for performing the seismic performance evaluation method for steel pipe piles described in claim 1, The characteristic value of the pile β (upper bar), the outer diameter D of the steel pipe pile, the plate thickness t, and the yield point σ. ｙ Young's modulus E ｐ A step of calculating the index (1) using, Using the formula (6) which employs the aforementioned index (1), the energy absorption share ratio E of the steel pipe pile up to its ultimate state is used. ｐｉｌｅ A calculation program that performs the steps of evaluating the seismic performance of a steel pipe pile up to its ultimate state, where the pile head of the steel pipe pile is rotatably free-connected or rotatably semi-rigid-connected. Here, c, d, and e are constants. [Number 10]

22. In the above formula (6), The constant a satisfies the range -3 ≤ a ≤ 1. The arithmetic program according to claim 20 or 21, wherein the constant b satisfies the range 0.5 ≤ b ≤ 3.

5.

23. The degree of rotational restraint of the pile head of the steel pipe pile, indicated by the degree of pile head fixation f, satisfies the range of 0 ≤ f < 1. In the above formula (6), The constant c satisfies the range 37.97 - 8.50f ≤ c ≤ 44.89 - 10.16f. The constant d satisfies the range -0.09 - 0.01f ≤ d ≤ -0.05 - 0.01f. The arithmetic program according to claim 22, wherein the constant e satisfies the range -6.0 + 1.5f ≤ e ≤ 6.0 - 1.5f. Here, at the degree of pile head fixation f, In the case of the pile head free condition, where there is no constraint on the rotation of the pile head, f = 0, and the closer f approaches 1, the greater the constraint on rotation.

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