JP6471445B2 - Cast-in-place pile design method, design program, storage medium, and cast-in-place pile design system - Google Patents

Description

  The present invention relates to a design method for a cast-in-place pile in which a steel pipe is wound around a pile head, a design program, a storage medium, and a cast-in-place pile design system.

  A cast-in-place pile is formed by drilling a pile hole from the ground surface in the ground, placing a reinforcing member such as a reinforcing bar cage in the pile hole, and then placing concrete. For this reason, it is possible to increase the diameter and length of the pile compared to a ready-made pile that is driven into the ground by a pile manufactured at the factory, and is used when constructing foundations that require a large bearing capacity. . In order to improve the earthquake resistance of cast-in-place piles, steel pipes are wound around the pile heads of cast-in-place piles, and earthquake-resistant cast-in-place piles that ensure the bending and shear strength of piles, that is, pile head cast-in-place concrete cast piles are widely used. It is used. The pile head steel-winding cast-in-place concrete pile has a structure in which the upper part of the pile is a steel pipe concrete part or a steel pipe reinforced concrete part, and the lower part of the pile is a reinforced concrete part.

  The joint near the boundary between the upper part and the lower part of the pile and where the main reinforcement and the steel pipe that make up the pile head cast-in-place concrete pile overlap in the longitudinal direction acts on the upper part of the pile during an earthquake, etc. It is necessary to reliably transmit the axial force, bending moment, and shearing force to the lower part of the pile. For example, Patent Document 1 discloses a cast-in-place in which a plurality of tubular ribs are provided on the inner peripheral surface on the lower end side of a steel pipe to prevent slippage between the steel pipe and the internal concrete, and stress transmission is possible from the upper pile to the lower pile. Pile is disclosed.

  Of the pile head cast steel cast-in-place concrete piles, in the SC type in which the main reinforcement does not penetrate the steel pipe concrete part, the specification of the joint part is particularly important. About the specification of a joint part, the content of the specification including the length of a joint part is disclosed by the nonpatent literature 1. FIG. Furthermore, Non-Patent Document 2 discloses that it is preferable to make the length of the joint part 45 times the main muscle diameter without considering the length and pile diameter of the pile head steel winding cast-in-place concrete pile. Yes.

JP 2006-138095 A

"KCTB cast-in-place steel pipe concrete pile" (Seismic pile association), 14-15 pages, October 1990) "Construction Common Specification 1997 Edition" (Public Building Association, pp. 32-37)

  However, as described above, it is necessary for the joint portion to reliably transmit the bending moment and shear force to the lower portion of the pile in addition to the axial force that acts on the upper portion of the pile during an earthquake or the like. For this reason, when designing cast-in-place concrete piles with pile head steel pipes, the optimal length of the joint should be calculated based on not only the transmission of axial force but also the bending moment, etc., and its specifications should be set. Is required. In Patent Document 1, mention is made regarding enabling stress transmission in the axial direction, but regarding designing an optimum specification of the joint part based on the bending moment and shearing force acting on the joint part, Not mentioned. Non-patent documents 1 and 2 refer to specifications such as the length of the joint, but do not refer to designing an optimal specification of the joint based on the bending moment and shearing force. .

  And since there are various types of length and pile diameter of the pile head steel winding cast-in-place concrete pile, the length of the joint portion is not uniformly set to about 45 times the main muscle diameter, but the pile It is considered preferable to set a desired size as appropriate according to the diameter and the like. That is, if the length of the joint part where the steel pipe concrete part and the upper end part of the main reinforcement of a reinforced concrete part overlap is made larger than necessary, it will become an excessive design which has the stress transmission capability more than necessary, and will become an uneconomic design. On the other hand, if the length of the joint portion is not ensured, the stress from the steel pipe concrete portion to the reinforced concrete portion cannot be sufficiently transmitted, and there is a possibility that problems such as pile breakage may occur.

  The present invention has been made in view of the above-mentioned problems, and is a new and improved cast-in-place pile capable of theoretically designing the optimal joint portion specifications with respect to a bending moment acting by an external force such as an earthquake. It is an object to provide a design method, a design program, a storage medium, and a cast-in-place pile design system.

One aspect of the present invention is a design method of a cast-in-place pile in which a reinforced concrete part and a steel pipe concrete part provided thereabove are integrated, from the reinforced concrete part toward the inside of the steel pipe concrete part. Including a bending moment examination step of examining a bending moment in a joint portion where an internal reinforced concrete portion in the reinforced concrete portion including the upper end portion of the extended reinforcing steel bar and a steel pipe of the steel pipe concrete portion overlaps, and the bending moment examination step includes The inner circumference of the steel pipe in the joint section through the internal reinforced concrete portion of the joint section due to a bending moment generated in the cast-in-place pile when a substantially horizontal load is applied to the upper part of the cast-in-place pile a compressive stress acting between the surface and the outer peripheral surface of the inner concrete portion, the compressed response After calculating a balance relational expression with the tensile stress of the steel pipe acting in the opposite direction, the concentration acting on the inner peripheral surface of the steel pipe in the joint section by the compressive stress, the tensile stress and the bending moment A balance examination step for calculating a relational expression with the load, a stress calculation step for calculating the compressive stress and the tensile stress based on the relational expressions calculated by the balance examination step, and the compression stress, respectively. And an allowable value examining step for examining whether or not each of the tensile stress is within a predetermined allowable value range.

  According to one aspect of the present invention, a bending moment generated in a steel pipe concrete portion due to a horizontal load acting on a pile upper portion of a cast-in-place pile during an earthquake or the like is generated between the steel pipe in the joint section and the internal reinforced concrete portion in the joint section. It is possible to reliably transmit to the reinforced concrete part by the lever action generated in. In order to set the specifications of the joint based on the compressive stress and tensile stress generated by the lever action, it is possible to design an optimum specification for the bending moment.

  At this time, in one aspect of the present invention, after the bending moment examining step, further includes a shearing force examining step of examining a shearing force in the joint portion, and the shearing force examining step acts on the joint portion. A total shearing force calculating step for calculating a total shearing force which is a sum of a shearing force applied by a bending moment and a shearing force acting on the joint by the load in the substantially horizontal direction; The internal reinforced concrete partial shear force examination step for examining whether the internal reinforced concrete portion is within the allowable range of the shear strength, and whether the total shear force is within the allowable range of the steel pipe of the joint And a steel pipe shear force examination step.

  If it does in this way, after considering the shear force of a steel pipe part and an internal reinforced concrete part, a joint part can be designed to a more suitable specification.

  Further, in one aspect of the present invention, the shear force examination step is set in a joint part specification setting step for setting a diameter, a material, and a pitch of a shear reinforcing bar in the joint part, and the joint part specification setting step. A shear strength calculation step of calculating a shear strength of the inner reinforced concrete portion of the joint portion and a shear strength of the steel pipe of the joint portion in the specification, respectively.

  If it does in this way, a joint part can be designed to a more suitable specification also based on the shearing force which acts on a joint part.

  Further, in one aspect of the present invention, among the allowable value examination step, the internal reinforced concrete partial shear force examination step, and the steel pipe shear force examination step, a test ratio indicating a ratio of the calculated value to the allowable value in these steps is The maximum step may further include a test ratio examination step for examining the validity of the test ratio.

  In this way, when the design value of the joint portion is not appropriate, the design can be performed again from a more suitable process, so that the design design of a suitable joint portion can be performed efficiently.

  Moreover, in one aspect of the present invention, when it is determined that the calculated value in the tolerance examination step, the internal reinforced concrete partial shear force examination step, and the steel pipe shear force examination step is outside the tolerance range, Alternatively, when the verification ratio is determined to be invalid in the verification ratio examination step, the specification selection cost comparison step of comparing the specification selection of the joint part or the specification selection of the steel pipe winding portion on which the steel pipe is attached May be further included.

  If it does in this way, the design from a more suitable process can be redone after considering the required cost for eliminating the malfunction of the designed joint part.

  Moreover, in one aspect of the present invention, in the tolerance examination step, the steel pipe at the time of final design and the concrete strength filled in the steel pipe as the predetermined tolerance, or the steel pipe at the time of short-term design and the steel Any of the standard strengths of concrete may be used.

  If it does in this way, the suitable specification of the joint part of a cast-in-place pile under a desired use condition can be designed efficiently.

  Moreover, the other aspect of this invention is a design program for making a computer perform the design method of the cast-in-place pile in any one mentioned above.

  According to another aspect of the present invention, the joint portion can be efficiently designed to a specification having a suitable length in accordance with such a design program.

  Another aspect of the present invention is a storage medium in which a computer-readable design program for causing a computer to execute any one of the above-described cast-in-place pile design methods is stored.

  According to another aspect of the present invention, the joint portion can be efficiently designed to have a suitable length according to the design program stored in the storage medium.

Another aspect of the present invention is a design system for a cast-in-place pile in which a reinforced concrete portion and a steel pipe concrete portion provided thereabove are integrated, and at least the ground where the cast-in-place pile is provided A storage unit for storing predetermined data relating to the design of the cast-in-place pile including soil data, specification data relating to the components of the cast-in-place pile, and past design performance data of the cast-in-place pile; Based on the data and the bending moment in the joint part where the internal reinforced concrete part in the reinforced concrete part and the steel pipe of the steel pipe concrete part including the upper end part of the reinforcing steel bar extending from the reinforced concrete part to the steel pipe concrete part are desired. After calculating the design value of the length of the joint, and examining the validity of the design value, the joint A calculation unit that determines a specification of the bending part, a bending moment setting unit that sets a bending moment in the joint part, a shearing force setting part that sets a shearing force in the joint part, and the joint part A bending moment determination unit that examines the validity of the bending moment, a shear force determination unit that examines the validity of the shear force of the steel pipe and the internal reinforced concrete portion in the joint, and at least the bending moment determination unit and A joint part specification determining unit that determines a specification of the joint part based on a determination result of the shearing force determination part, and the bending moment determination part has the length by the bending moment The inner peripheral surface of the steel pipe in the joint section and the internal rebar concrete through the internal reinforced concrete section of the section A balance relation between the compressive stress acting between the outer peripheral surface of the steel pipe part and the tensile stress of the steel pipe acting in the opposite direction to the compressive stress, and then calculating the compressive stress, the tensile stress and the bending After calculating the relational expression with the concentrated load acting on the inner peripheral surface of the steel pipe in the joint section by the moment, the compressive stress and the tensile stress are studied while considering the balance between the compressive stress and the tensile stress. the calculated respectively, the compressive stress and the tensile stress, respectively, wherein Rukoto which have a function to consider whether within a predetermined tolerance.

  According to another aspect of the present invention, the optimal length of the joint portion is set based on the bending moment acting on the joint portion in the calculation portion, and then the appropriate value for the bending moment and shear force of the joint portion at the set value is set. Since the final specification of the joint portion is set after examining the properties, it is possible to efficiently design the joint portion having a suitable specification.

  As described above, according to the present invention, the optimum length of the joint portion can be calculated based on the bending moment acting on the joint portion, and the specification can be set. For this reason, the specification of the joint part which does not become an overspec can be designed efficiently.

It is a longitudinal cross-sectional view explaining the structure of the cast-in-place pile designed by the design method of the cast-in-place pile which concerns on one Embodiment of this invention. It is a block diagram which shows the whole structure of the design system of the cast-in-place pile which concerns on one Embodiment of this invention. It is a flowchart which shows the outline of the design method of the cast-in-place pile which concerns on one Embodiment of this invention. It is a flowchart which shows the detail of the examination process of the bending stress and shearing force of the steel pipe upper part contained in the design method of the cast-in-place pile which concerns on one Embodiment of this invention. (A) thru | or (C) is explanatory drawing which shows the verification result used as the premise of the design method of the cast-in-place pile which concerns on one Embodiment of this invention. (A) thru | or (C) is explanatory drawing which shows the verification result used as the premise of the design method of the cast-in-place pile which concerns on one Embodiment of this invention. It is a flowchart which shows the detail of the bending stress examination process of the joint part contained in the design method of the cast-in-place pile which concerns on one Embodiment of this invention. It is a flowchart which shows the detail of the shear-force examination process included in the design method of the cast-in-place pile which concerns on one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are essential as means for solving the present invention. Not necessarily.

  First, the outline of the structure of a cast-in-place pile designed by the cast-in-place pile design method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view illustrating a configuration of a cast-in-place pile designed by a design method for cast-in-place pile according to an embodiment of the present invention.

  As shown in FIG. 1, the cast-in-place pile 10 according to the present embodiment is an earthquake-resistant cast-in-place pile in which a steel pipe 18 is wound around a pile head 11 a of the pile body 11, that is, a pile-head steel tube-wound cast-in-place concrete pile. is there. In other words, the cast-in-place pile 10 according to the present embodiment is an SC-type pile head steel tube-wound cast-in-place concrete pile in which the upper part of the pile is made of the steel pipe concrete part 12 and the lower part of the pile is the reinforced concrete part 14. Moreover, the cast-in-place pile 10 of this embodiment is a bottom expansion pile in which the bottom part 14b of a substantially truncated cone shape is provided in the lower part side of the reinforced concrete part 14. FIG. An upper end portion 16 a of the main reinforcement 16 of the reinforced concrete portion 14 extends to the lower end side of the steel pipe concrete portion 12. The cast-in-place pile 10 includes an SRC type in which the main reinforcement 16 penetrates the steel pipe concrete portion 12 and an SC type in which the main reinforcement 16 does not penetrate the steel pipe concrete portion 12.

  As shown in FIG. 1, the steel pipe concrete part 12 is mainly comprised by the substantially cylindrical steel pipe 18 and the internal concrete 20 with which the inner space is filled. In the present embodiment, as the steel pipe 18, for example, a flat steel pipe having a diameter of about 700 mm to 2500 mm and a flat inner peripheral surface is used. Thus, by installing the steel pipe 18 on the pile upper side of the cast-in-place pile 10, the shear strength and the bending strength can be improved and a pile body excellent in economic efficiency and procurement power can be obtained.

  In addition, in FIG. 1, although the SC type pile head steel pipe winding cast-in-place concrete pile is shown as the cast-in-place pile 10, when it is set as SRC type, the internal structure part provided in the inner space of the steel pipe 18 is an inside. It becomes reinforced concrete. The “internal structure portion” referred to in the present specification indicates the internal concrete 20 or the internal reinforced concrete provided inside the steel pipe 18.

  During an earthquake, the horizontal force and variable axial force from the superstructure are input to the pile head. As a result, a bending moment or a shearing force acts on the cast-in-place pile 10. In order to counter such bending moment and shearing force, a steel pipe 18 is wound around the pile head 11a of the pile body 11 to increase the bending strength and shear strength of the pile body 11.

  On the lower end side of the steel pipe concrete portion 12, a joint in which the internal reinforced concrete portion 15 including the upper end portion 16 a of the main reinforcement 16 extending from the reinforced concrete portion 14 toward the inside of the steel pipe concrete portion 12 overlaps with the lower portion 18 b of the steel pipe 18. A portion 13 is provided. That is, in the joint portion 13, the upper end portion 16 a of the main reinforcement 16 of the reinforced concrete portion 14 is embedded in the inner concrete 20 on the lower end side of the steel pipe concrete portion 12.

  When a bending moment acts on the joint portion 13, an insulator action is generated between the lower portion 18 b of the steel pipe 18 in the section of the joint portion 13 of the steel pipe concrete portion 12 and the internal reinforced concrete portion 15 included in the section of the joint portion 13. A compressive stress is generated between the inner surface of the steel pipe 18 and the internal reinforced concrete portion 15 in the section of the joint portion 13. Thereby, a bending moment can be reliably transmitted from the steel pipe concrete part 12 to the internal reinforced concrete part 15 and the reinforced concrete part 14 following the internal reinforced concrete part 15.

  That is, a bending moment is generated in the steel pipe concrete portion 12 by a horizontal load that acts on the upper portion of the cast-in-place pile 10 during an earthquake or the like. And the said bending moment is reliably transmitted to the reinforced concrete part 14 by the lever action which arises between the lower part 18b of the steel pipe 18 in the area of the joint part 13, and the internal reinforced concrete part 15 in the area of the joint part 13. FIG.

  Therefore, in this embodiment, a design method of the cast-in-place pile 10 by the design system 100 (see FIG. 2) described below is performed, and the optimum is more efficiently and reliably based on the bending moment acting on the joint portion 13. The length L of the joint portion 13, in other words, the wrap length L in which the internal concrete 20 of the steel pipe concrete portion 12 wraps the upper end portion 16 a of the main reinforcement 16 is obtained. The design system 100 can efficiently design the joint portion 13 having a specification having the wrap length L as the optimum value. That is, when transmitting the bending moment from the upper part of the pile to the lower part of the pile, the compressive stress generated between the inner surface of the lower part 18b of the steel pipe 18 and the outer peripheral surface of the internal reinforced concrete part 15 by the lever action, and the axis of the lower part 18b of the steel pipe 18 Since the specification of the joint portion 13 is set based on the tensile stress generated in the directional cross section, the optimum specification for the bending moment can be designed.

  In addition, in this embodiment, when designing SC type pile head steel pipe winding cast-in-place concrete pile, the design method and design system which concern on one Embodiment of this invention are applied, However, SRC type pile head Even a steel pipe winding cast-in-place concrete pile can be applied to a cast-in-place pile having a configuration in which a part of the main bar does not penetrate the inner concrete of the steel pipe wound part and a joint is provided at the lower part of the steel pipe.

  Next, the structure of the cast-in-place pile design system according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram illustrating the overall configuration of a cast-in-place pile design system according to an embodiment of the present invention.

  The cast-in-place pile design system 100 according to the present embodiment is used when the cast-in-place pile 10 constructed by integrating the reinforced concrete portion 14 and the steel pipe concrete portion 12 provided thereabove is used. As shown in FIG. 2, the design system 100 includes a computer 101 owned by a user who accesses a database server having a database that stores predetermined data related to the design of the cast-in-place pile 10 and performs search processing. The optimum lap length L of the joint portion 13 with respect to the bending moment from is obtained. And when the design system 100 transmits the bending moment acted on by the external force etc. from the pile upper part to the pile lower part, in order to set the specification of the joint part 13 based on the compressive stress and the tensile stress generated by the lever action. It is used when designing the optimum specification of the joint part 13 with respect to the bending moment.

  In the present specification, the “user” refers to a person who performs the design or construction work of the cast-in-place pile 10. The “computer” refers to an information terminal provided with an arithmetic device capable of various arithmetic processes such as a super computer, a general-purpose computer, an office computer, a control computer, a personal computer, and a portable information terminal.

  In the process of designing the cast-in-place pile 10, the design system 100 of the present embodiment calculates the lap length L that is the optimum value of the joint portion 13 based on the magnitude of the bending moment M acting on the joint portion 13. Used when setting the specifications. The design system 100 calculates an optimal lap length L that enables the stress transmission of the bending moment M acting on the joint portion 13 by the computer 101 based on predetermined data related to the design of the cast-in-place pile 10. Therefore, the validity of the joint portion 13 having the wrap length L is determined by examining its validity. Note that the configuration of the design system 100 is not limited to FIG. 2, and various modifications such as omitting some of the components or adding other components are possible.

  As shown in FIG. 2, the computer 101 includes a storage unit 102, a CPU (Central Processing Unit) 110, an input unit 120, an output unit 122, a communication unit 124, a ROM (Read Only Memory) 108, and a RAM (Random Access Memory) 106. , And a storage medium 104, and these components are electrically connected to each other via a system bus 125. Therefore, the CPU 110 accesses the storage unit 102, ROM 108, RAM 106, and storage medium 104, grasps the operation state of the input unit 120, outputs data to the output unit 122, and transmits / receives various information to / from the Internet 126 via the communication unit 124. Etc.

  The storage unit 102 is a database server having a function of storing at least predetermined data relating to the design of the cast-in-place pile 10. In this embodiment, the memory | storage part 102 is the structure of pile bodies 11 such as the soil soil data, the steel pipe 18 and the internal structure part 20, the main reinforcement 16, SRC, SC at least as the predetermined data. The specification data related to the elements and the past design performance data of the cast-in-place pile 10 are stored in a database.

  Since the joint part 13 can be set to a desired length L based on predetermined data relating to the design of such a cast-in-place pile 10, the specification of the joint part 13 having the length L can be determined efficiently. become. Also, by accumulating these data in the storage unit 102, when the cast-in-place pile 10 is provided at another construction site, the accumulated lap data stored in the storage unit 102 is used to obtain an optimum lap length. The specification of the joint part 13 having L can be obtained with higher accuracy.

  The CPU 110 has a function of controlling the operation of each component included in the design system 100 in accordance with data received via the communication unit 124 and various programs stored in the ROM 108 and the storage medium 104. In addition, the CPU 110 has a function of appropriately storing necessary data and the like in the RAM 106 that temporarily stores these various processes.

  In the present embodiment, the CPU 110 calculates the length of the desired joint portion 13 based on the bending moment M acting on the joint portion 13 by performing arithmetic processing with a computer based on predetermined data related to the design of the cast-in-place pile 10. It functions as a calculation unit that performs various calculation processes necessary for calculating L. That is, the CPU 110 calculates the lap length L of the desired joint portion 13 based on at least the predetermined data, calculates the lap length L of the desired joint portion 13, and acts on the joint portion 13 having the wrap length L. After examining the validity for the moment, it has a function of determining the joint portion 13 having the specification having the length L.

  In the present embodiment, the CPU 110 includes a setting unit 112, a determination unit 114, and a determination unit 116. In the present specification, the “predetermined data” related to the design of the cast-in-place pile 10 is at least soil data of the ground where the cast-in-place pile 10 is provided, the steel pipe 18 and the internal structure portion 20, the main reinforcement 16, SRC, It refers to various data such as specification data relating to the components of the pile body 11 such as SC and past design performance data of the cast-in-place pile 10. That is, “predetermined data” means that, in the process of designing the cast-in-place pile 10, the optimum value of the lap length L of the joint portion 13 is obtained based on the bending moment acting on the joint portion 13, and the specification is It refers to various data necessary to determine and is used to determine the pile type.

  In the process of designing the cast-in-place pile 10 with the design system 100, the setting unit 112 is configured to obtain an optimum value of the length L of the joint portion 13 based on predetermined data related to the design of the cast-in-place pile 10. It has a function of setting a bending moment or the like to be applied to the portion 13. In the present embodiment, the setting unit 112 has a function as a bending moment setting unit that sets a bending moment in the joint part 13 and a function as a shearing force setting part that sets a shearing force in the joint part 13.

  In this embodiment, the setting part 112 is the bending moment setting part, and the inner peripheral surface of the steel pipe 18 and the internal reinforced concrete part in the section of the joint part 13 by a bending moment generated by a horizontal load acting on the pile upper part of the cast-in-place pile 10. 15 has a function of calculating a balanced relational expression between the compressive stress generated between the steel pipe 18 and the tensile stress of the steel pipe 18 acting in the opposite direction to the compressive stress. The setting unit 112 functions as a bending moment setting unit to calculate a relational expression between a compressive stress and a tensile stress and a concentrated load acting on the inner peripheral surface of the steel pipe 18 in the joint section by the bending moment, And a function of calculating compressive stress and tensile stress based on the calculated relational expression.

  Further, in the present embodiment, the setting unit 112 is a total shearing force setting unit that is a total of a shearing force acting on the joint part 13 due to a bending moment and a shearing force acting on the joint part 13 due to a load in a substantially horizontal direction. Has the function of calculating the shear force. The setting unit 112 functions as a shear force setting unit to set the specifications of the joint part 13 including at least the diameter, material, and pitch of the shear reinforcement, and the shear strength of the internal reinforced concrete portion 15 of the joint part 13 in such specifications. And the function of calculating the shear strength of the steel pipe 18 of the joint portion 13.

  The determination unit 114 has a function of determining validity of various data set based on predetermined data related to the design of the cast-in-place pile 10 in the process of designing the cast-in-place pile 10 with the design system 100. In the present embodiment, the determination unit 114 has a function as a bending moment determination unit that examines the validity of the design value of the joint portion 13 with respect to at least the bending moment set by the setting unit 112. Specifically, as the bending moment determination unit, the determination unit 114 has a predetermined compressive stress acting on the inner surface of the steel pipe of the joint portion 13 due to the bending moment and a tensile stress of the steel pipe 18 acting in a direction opposite to the compressive stress. Consider whether it is within the allowable range.

  Further, the determination unit 114 has a function as a shear force determination unit that examines the validity of the design value of the joint unit 13 with respect to the shear force of the steel pipe portion 12 and the internal reinforced concrete portion 15 in the joint portion 13. Specifically, the determination unit 114 functions as a shear force determination unit to examine whether or not the total shear force is within the allowable range of the shear strength of the internal reinforced concrete portion 15 of the joint portion 13, and the total shear force is the joint portion. It has a function of examining whether or not the 13 steel pipes 18 are within the allowable range of the shear strength.

  The determination unit 116 has a function of determining optimum values of various data set based on predetermined data relating to the design of the cast-in-place pile 10. In the present embodiment, the determination unit 116 has a function of determining the specification of the joint unit 13 based on the determination result of the determination unit 114. Specifically, when the bending stress is applied to the joint portion 13 for which the specification such as the lap length L is selected in the simulation, the determining unit 116 determines that the generated lap is within the allowable range. The specification of the joint portion 13 having the length L is determined.

  The input unit 120 has a function of inputting various data such as predetermined data related to the design of the cast-in-place pile 10, and for example, a mouse, a keyboard, a touch panel, or the like is used. In the present embodiment, the input unit 120 inputs characters and various data when operating the setting unit 112, the determination unit 114, and the determination unit 116, for example.

  Moreover, in this embodiment, the input part 120 inputs the bending moment, the shear force, etc. which act on the joint part 13 by simulation based on the predetermined data concerning the design of the cast-in-place pile 10, and assumes the specification. It is also used when inputting necessary data or the like when determining the validity of the designed value of the joint portion 13. That is, the input unit 120 is used when inputting various data stored in the storage unit 102 or when inputting various data for determining specifications such as the lap length L of the joint unit 13.

  The output unit 122 has a function of outputting a calculation result by the CPU 110, information on the storage unit 102 serving as a database, and the like. For example, a display monitor or the like is used as the output unit 122. In the present embodiment, the output unit 122 performs screen display when the setting unit 112, the determination unit 114, and the determination unit 116 are operated, for example.

  The storage medium 104 is a medium readable by the computer 101 and has a function of storing programs, data, and the like. The function of the storage medium 104 can be realized by various memories such as an optical disk (CD, DVD), HDD, or USB memory. The storage medium 104 stores a design program for realizing the function of each component of the design system 100 of the present embodiment so that the computer 101 can read it.

  For this reason, each process in the design method of the cast-in-place pile 10 which concerns on this embodiment by the said design program comes to be performed by implement | achieving the function of each component of the said design system 100. FIG. In addition, the detail of the design method of the cast-in-place pile 10 based on this embodiment performed by the said design program is mentioned later.

  As described above, according to the design system 100 of the present embodiment, after setting design values such as the lap length L of the joint portion 13 based on predetermined data relating to the design of the cast-in-place pile 10, the setting is performed. The final joint part 13 can be determined as the design value by examining and determining the appropriateness of the joint part 13 with respect to the bending moment and the shearing force. For this reason, the specification of the joint part 13 having a suitable wrap length L can be efficiently designed based on predetermined condition data on which the cast-in-place pile 10 such as the pile condition and the construction condition is constructed.

  For this reason, when the joint part 13 is designed, the joint part 13 that secures the lap length L so as not to be over-specific can be reliably designed. In addition to the specification setting of the steel pipe 18 and the specification setting of the internal structure part 20 of the steel pipe 18 according to the bending moment required by the steel pipe winding part, the wrap length L of the steel pipe 18 can be set to an appropriate value. A more economical pile head steel tube winding cast-in-place pile 10 can be designed.

  Next, a method for designing a cast-in-place pile according to an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a flowchart showing an outline of a method for designing a cast-in-place pile according to an embodiment of the present invention.

  In the design method of the cast-in-place pile 10 according to the present embodiment, the validity of the design value such as the lap length L of the joint portion 13 is determined. The focus is on determining the design value specifications.

In the present embodiment, first, a design external force is calculated using predetermined data relating to the design method of the cast-in-place pile 10 (step S101). Specifically, the design horizontal force, normal axial force N _L , fluctuating axial force N _E , earthquake axial force minimum value N _L−E , and earthquake axial force maximum value N _{L + E} are included as the design external force. calculate. Note that the minimum value N _L-E Seismic axial force is the difference always the axial force N _L and variable axial force _{N E (N L -N E)} , the maximum value N _{L + E} Seismic axial force Is the sum (N _L + N _E ) of the constant axial force N _L and the variable axial force N _E.

  Next, ground information such as geological data at the construction site of the cast-in-place pile 10 to be designed is input (step S102). In the flowchart shown in FIG. 3, the present step S102 is performed after the step S101. However, these steps S101 and S102 may be performed simultaneously or the step S102 may be performed before the step S101.

  When the calculation of the design external force and the input of ground information are completed, the initial design conditions for designing the cast-in-place pile 10 such as the construction method, the tip pile diameter, and the pile length are selected (step S103). Specifically, the conditions are selected by calculating the supporting force and the pulling resistance determined from the ground on which the cast-in-place pile 10 is constructed.

  When the selection of design initial conditions is completed, specifications such as pile diameter, reinforcing bar diameter, number of reinforcing bars, reinforcing bar arrangement diameter, reinforcing bar material, and concrete strength of the reinforced concrete portion 14 are then selected (step S104). Specifically, the specification is selected by calculating the compression strength and tensile strength determined from the pile body 11.

  If the specification of the reinforced concrete part 14 is selected, next, the specification of the steel pipe concrete part 12 will be selected (process S105). Specifically, the selection of the steel tube winding part to be SRC type or SC type, pile diameter, steel pipe material, steel pipe length, steel pipe plate thickness, concrete strength, reinforcing bar diameter, number of reinforcing bars, reinforcing bar arrangement Select specifications such as diameter and rebar material.

  And if the specification of a steel pipe winding part is selected, the number of piles and pile arrangement | positioning in the construction place of the cast-in-place pile 10 will be set next (process S106).

  Next, a simulation is performed using the horizontal force for design calculated in step S101 and the ground information input in step S102, and the bending moment and shear force generated in the steel pipe concrete portion 12 of the pile body 11 are examined (step S107). ). Specifically, the validity of the bending moment and the shearing force generated in the upper part of the steel pipe concrete part 12 by the horizontal force for design is checked. A detailed description of the step S107 for examining the bending moment and the shearing force will be described later.

  If the bending moment and the shearing force of the steel pipe concrete part 12 are examined, next, the lower part of the steel pipe concrete part 12, that is, the bending moment of the joint part 13 is examined (step S108). Specifically, it is checked whether or not the design value such as the lap length L of the joint portion 13 is an appropriate value for the bending moment generated by the simulation. In addition, detailed description of process S108 which considers the bending moment of the joint part 13 is mentioned later.

  If the bending moment of the joint part 13 is examined, next, the shearing force of the joint part 13 is examined (step S109). Specifically, it is checked whether or not the design value of the joint portion 13 is an appropriate value for the shearing force generated by the simulation. In addition, detailed description of process S109 which considers the shearing force of the joint part 13 is mentioned later.

  Next, the validity of the test ratio indicating the ratio of the generated value to the allowable value of the bending moment and the shearing force with respect to the design value of the joint portion 13 is examined (step S110). Specifically, an allowable value examination step S108-8 (see FIG. 7) included in the bending moment examination step S108, an internal reinforced concrete partial shear force examination step S109-4 (see FIG. 8) included in the shear force examination step S109, and Of the steel pipe shearing force examination step S109-5 (see FIG. 8), the step where the test ratio indicating the ratio of the calculated value to the allowable value in these steps is maximized is detected, and the validity of the test ratio in this step is examined. To do.

  In the test ratio examination step S110, when it is determined that the test ratio in the allowable value examination step S108-8 is the maximum and the test ratio is not appropriate, the process returns to step S108-2 and the joint portion 13 The process starts again from the selection of the specification of the wrap length L, or returns to step S105 and starts again from the selection of the specification of the steel pipe concrete portion 12.

  If the verification ratio in the internal reinforced concrete partial shear force examination step S109-4 is the maximum and it is determined that the verification ratio is not appropriate, the process returns to step S109-2 to return the internal reinforced concrete portion of the joint 13 From the selection of specifications such as the diameter, material, and pitch of the 15 shear reinforcement bars, the process returns to step S108-2 (see FIG. 7) included in the bending moment examination step S108, and the lap length L of the joint portion 13 is set. The process starts again from the specification selection, or returns to step S105 and restarts from the selection of the specifications of the steel pipe winding portion.

  Furthermore, when the test ratio in the steel pipe shear force examination step S109-5 is the maximum and it is determined that the test ratio is not appropriate, the process returns to step S108-2 and the lap length L of the joint portion 13 is determined. Or restart from the selection of the specifications for the steel pipe winding part. As described above, the design of the cast-in-place pile 10 can be efficiently performed because the design of the joint portion 13 can be redone from a more suitable process in consideration of the validity of each data used for the design of the joint portion 13. .

  After the examination of the examination ratio is completed, the examination for subsidence is performed (step S111). Specifically, the settlement condition of the pile body 11 at the construction site of the cast-in-place pile 10 is performed by simulation or the like. If it is determined in this step S111 that the subsidence conditions are not appropriate, as shown in FIG. 3, the process returns to step S103 and starts again from the selection of the design initial conditions in order to secure a more preferable subsidence condition.

  After the examination for settlement, the pile head joints, pile caps, and foundation beams related to the pile head are finally examined (step S112), and then the pile conditions such as the number of piles, pile arrangement, pile specifications, etc. A final decision is made (step S113). And the design by the design method of the cast-in-place pile 10 which concerns on this embodiment is completed.

  Thus, in the design method of the present embodiment, the design value of the lap length L of the joint portion 13 is calculated based on the predetermined data related to the design of the cast-in-place pile 10, and then the design value is calculated. The validity of bending moment and shear force is examined by simulation. And if the validity of the design value of the lap length L of the joint part 13 is confirmed with respect to the bending moment and the shearing force, the wrap length L is determined as the design value, and the wrap length L It is possible to efficiently design the joint portion 13 having

  For this reason, the excessive design in which the lap length L of the joint part 13 is unnecessarily large can be prevented in advance, and the labor and cost of construction can be reduced. Moreover, since the lap length L of the joint part 13 can be set to an optimum value with respect to the type, pile diameter, pile length, etc. of the pile to be changed according to the ground strength, the optimum and economical design of the cast-in-place pile 10 And can be constructed.

  Next, the detail of the process which examines the bending moment and shearing force of the steel pipe concrete part 12 contained in the design method of the cast-in-place pile concerning one Embodiment of this invention is demonstrated, using drawing. FIG. 4 is a flowchart showing details of step S107 for examining the bending moment and shearing force of the steel pipe concrete portion 12.

  First, as shown in FIG. 4, the bending moment generated in the steel pipe concrete part 12 is calculated using the design horizontal force calculated in step S101 (step S107-1). Next, the bending strength of the steel pipe concrete portion 12 is calculated (step S107-2).

  In this embodiment, the bending strength calculation step S107-2 is performed after the bending stress calculation step S107-1. However, even if these steps S107-1 and S107-2 are performed simultaneously, the step S107-2 is performed. May be performed prior to step S107-1.

  Next, the bending moment calculated in step S107-1 is examined (step S107-3). Specifically, in step S107-3, the validity of the bending moment with respect to the bending strength calculated in step S107-2 is examined. If it is determined in this step S107-3 that the bending moment is not an appropriate magnitude with respect to the bending strength, the process returns to step S105 as shown in FIG. 4 in order to secure a more favorable bending strength. Redo from selection of specifications for steel pipe winding part.

  If it is determined in Step 107-3 that the bending moment is appropriate for the bending strength, then the shear force generated in the steel pipe concrete portion 12 by the horizontal force for design is calculated (Step S107-4). The shear strength of the steel pipe concrete part 12 is calculated (step 107-5). These shear force and shear strength may be calculated sequentially or simultaneously.

  And if the shear force and shear strength in the steel pipe concrete part 12 are calculated, next, examination with respect to a shear force will be performed (process S107-6). Specifically, it is examined whether the shear force is an appropriate magnitude with respect to the shear strength. If it is determined in this step S107-6 that the shear force is not an appropriate magnitude with respect to the shear strength, the process returns to step S105 as shown in FIG. 4 in order to secure a more suitable shear strength. Redo from selection of specifications for steel pipe winding part. By passing through such a flow, the cast-in-place pile 10 can be efficiently designed while checking the validity of the bending moment and shearing force of the steel pipe concrete part 12.

  Next, details of the design method of the cast-in-place pile according to one embodiment of the present invention will be described using the drawings. 5A shows a schematic diagram in which the vicinity of the joint portion 13 is enlarged, FIG. 5B shows a bending moment diagram in the schematic diagram, and FIG. 5C shows a shear force in the schematic diagram. The figure is shown. 6A shows a cross-sectional view in the direction perpendicular to the pile axis of the part A and B in FIG. 5A, and FIG. 6B shows the A part in FIG. 6A. A cross-sectional view showing only the upper half of the steel pipe is shown, and FIG. 6C is an explanatory diagram for obtaining a relational expression between the compressive stress and the tensile stress.

  As a result of intensive studies in order to achieve the above-described object of the present invention, the present inventor, when a bending moment acts on the joint portion 13, the lower portion 18 b of the steel pipe 18 in the section of the joint portion 13 and the section of the joint portion 13. In view of the fact that a lever action occurs between the inner reinforced concrete portion 15 and the stress is transmitted from the steel pipe concrete portion 12 to the reinforced concrete portion 14 due to the compressive stress acting on the inner surface of the lower portion 18b of the steel pipe 18. The design method of the joint part 13 which has the specification of the lap length L used as a value was discovered.

  That is, based on the verification results shown in FIGS. 5 (A) to (C) and FIGS. 6 (A) to (C), the detailed flow of the bending moment examination step S108 of the joint portion 13 shown in FIG. The detailed flow of the shearing force examination process S109 of the joint part 13 to be shown was found. Below, the detailed flow of the bending moment examination process S108 of the joint part 13 is demonstrated first, and the detailed flow of the shearing force examination process S109 of the joint part 13 is demonstrated next.

  In the design method of the cast-in-place pile according to this embodiment, in the bending moment examination step S108, the steps S108-1 to S108-9 shown in FIG. It is characterized by examining the validity of design values such as length L.

  First, the bending moment M generated in the pile body 11 by the horizontal force for design is calculated (step S108-1). Specifically, the bending moment M generated in the joint portion 13 is calculated with respect to the design horizontal force generated by the simulation.

  After the calculation of the bending moment M generated in the joint portion 13 is completed, the specification of the joint portion 13 is then selected (step S108-2). Specifically, in step S108-2, as the specification of the joint portion 13, the length of the joint portion 13, that is, the wrap length L of the lower portion 18b of the steel pipe 18 and the upper end portion 16a of the main reinforcement 16 is set to a desired size. Temporarily decide on the value.

  If the lap length L of the joint part 13 is tentatively determined, the case where the bending moments Ms and Mr act on the members composed of the S part and the RC part will be examined based on the stress transmission due to the lever action. At this time, as shown in FIG. 5A, it is assumed that the distribution shape in the pile axial direction of the compressive stress that the inner surface of the lower portion 18b of the steel pipe 18 receives from the internal reinforced concrete portion 15 in the joint portion 13 by lever action (process) S108-3). In this embodiment, the compression stress distribution shape is assumed to be a triangle in step 108-3. However, the compression stress distribution shape is assumed to be another shape such as a quadrangle or a trapezoid, and the subsequent steps are considered. May be.

  Once the distribution shape of the compressive stress is tentatively determined, the lap length of the lower portion 18b of the steel pipe 8 and the upper end portion 16a of the main reinforcing bar 16 is set to L, and the compressive stress σc is the center of gravity of the compressive stress distribution. It replaces with concentrated load Q which acts on (step S108-4). In this embodiment, by replacing the compressive stress σc with the concentrated load Q acting on the center of gravity of the compressive stress distribution, the stress center distance of the lever action becomes 2L / 3 as shown in FIG.

  After obtaining the concentrated load Q, next, the relationship between the bending moment M and the concentrated load Q is examined (step S108-5). At this time, the relationship between the concentrated load Q and the bending moment M is expressed by the following equation (1), and from the equation (1), the concentrated load Qs acting on the S portion and the concentrated load Qr acting on the RC portion are: Is represented by the following formula (2).

  Also, the bending moment diagram and the shear force diagram are as shown in FIGS. 5B and 5C, respectively. As shown in FIG. 5 (B), the bending moment M acting on the pile body 11 is constant in the pile axis direction when viewed as the whole pile body 11, but in the section of the joint portion 13, the S portion There is a bending moment gradient in the pile axis direction in each of the bending bending moment Ms and the bending bending moment Mr of the RC portion. For this reason, as shown in FIG. 5C, in the section of the joint portion 13, shear forces Qs and Qr are generated in the lower portion 18 b of the steel pipe 18 and the internal reinforced concrete portion 15, respectively.

  And the compressive stress which acts on the inner surface of the lower part 18b of the steel pipe 18 is examined. As shown in FIG. 6 (A), the upper half of the inner surface of the portion A of the lower portion 18b of the steel pipe 18 has a compressive stress acting upward as indicated by an upward arrow. As shown by the downward arrow, a compressive stress acts downward on the lower half of the inner surface of part B. Next, as shown in FIG. 6B, a balance between the compressive stress σc acting on the inner surface of the lower portion 18b of the steel pipe 18 and the tensile stress σt generated in the circumferential direction of the lower portion 18b of the steel pipe 18 will be considered. At that time, in order to obtain the compressive stress σc, as shown in FIG. 6C, if the inner radius of the steel pipe 18 is r, the plate thickness of the steel pipe 18 is t, and the central angle of the minute hatched portion is dφ, The force applied to the shaded portion shown in FIG. 6C is σc · rdφ. By summing up the circumferential component of this force and examining the balance between the compressive stress σc and the tensile stress σt (balance examination step S108-6), the following relational expression (3) is obtained.

  Multiplying the above formula (3) by the length L / 2 of the part A in the pile axis direction and a factor 1/2 for compressive stress having a triangular distribution, as shown in the following formula (4), the concentrated load Q is obtained.

From this formula (4), the following relational expression (4) ′ is obtained between the compressive stress σc and the tensile stress σt and the concentrated load Q. Therefore, the compressive stress σc and the tensile stress σt are obtained from the relational expression. Are respectively calculated (stress calculation step S108-7).
σc = 2Q / rL, σt = 2Q / tL (4) ′

  As described above, in the balancing examination step S108-6, the relational expression between the compressive stress σc and the tensile stress σt, the relational expression between the compressive stress σc and the concentrated load Q, and the relational expression between the tensile stress σt and the concentrated load Q are calculated. The balance between the compressive stress σc generated between the inner surface of the lower portion 18b of the steel pipe 18 and the internal reinforced concrete portion 15 and the tensile stress σt generated in the circumferential direction of the steel pipe 18 when a bending moment acts on the joint portion 13 is examined. To do.

  In the stress calculation step S108-7, a compressive stress σc, which is the magnitude of the compressive stress generated by the bending moment, and a tensile stress σt, which is the magnitude of the tensile stress, are respectively calculated. In the present embodiment, the compressive stress σc and the tensile stress σt are calculated based on the expressions (4) and (4) ′, which are relational expressions calculated in the balance examination step S108-6.

  Next, as the bending moment acting on the joint portion 13, the burden bending moment Ms on the S portion side and the burden bending moment Mr on the RC portion side are given, and the compressive stress σc and the tensile stress σt as the generated stress are expressed by the following formula ( It is confirmed that the relational expressions 5) and (6) are satisfied (allowable value examination step S108-8). Equation (5) shows the equation used for final design assuming the occurrence of rarely occurring large earthquakes, and Equation (6) is for short-term design assuming the occurrence of minor earthquakes that occur on a daily basis. The formula used is shown. Moreover, in Formula (5) and Formula (6), Fs shows the reference | standard intensity | strength of a steel pipe and Fc shows the design reference | standard intensity | strength of concrete.

  In the allowable value examination step S108-8, it is examined whether or not the compressive stress σc and the tensile stress σt are within a predetermined allowable range. Specifically, at the time of final design, it is examined whether the compressive stress σc and the tensile stress σt are within the allowable range based on the conditional expression (5) described above. On the other hand, at the time of short-term design, whether or not the compressive stress σc and the tensile stress σt are within the allowable range is examined based on the conditional expression (6) described above.

  If it is determined in step S108-8 that the compressive stress σc and the tensile stress σt are out of the allowable range, the cost required to start over from the specification selection of the joint portion 13 and the specification selection of the steel pipe concrete portion 12 are determined. The cost required when starting over is compared (specification selection cost comparison step S108-9). Then, if it is determined in the specification selection cost comparison step S108-9 that it is cheaper to redo the specification selection of the joint portion 13, the process returns to step S108-2 to return the lap length of the joint portion 13 as shown in FIG. Start over from L specification selection. On the other hand, if it is determined that it is cheaper to redo the specification selection of the steel pipe concrete part 12 in the specification selection cost comparison step S108-9, the process returns to the step S105 and redoes from the specification selection of the steel pipe concrete part 12. Thus, after examining the necessary cost for eliminating the malfunction of the joint part 13, it is possible to redo the design from a more suitable process, so the total cost in the pile design can be reduced.

  Moreover, the design method of the cast-in-place pile of this embodiment is the joint part 13 by the bending moment generated by simulation by performing each process S109-1 thru | or S109-6 shown in FIG. The validity of design values such as the lap length L of the joint portion 13 is examined with respect to the shearing force acting on the lower portion 18b of the steel pipe 18 and the internal reinforced concrete portion 15.

  As shown in FIG. 5C, a shearing force acts between the lower portion 18 b of the steel pipe 18 of the joint portion 13 and the internal reinforced concrete portion 15 as the bending moment M is transmitted. Therefore, in the shear force examination step S109, the total of the shear force applied by the bending moment M acting on the joint portion 13 and the shear force due to the seismic force is the ultimate shear strength of the lower portion 18b of the steel pipe 18 and the internal reinforced concrete portion 15. Or confirm that the short-term allowable shear strength is not exceeded.

  When the bending moment M with respect to the design value of the lap length L of the joint portion 13 is within the allowable range in the bending stress examination step S108, next, in the shear force examination step S109, the lap length of the joint portion 13 is determined. Examine the shear force against the design value of L. At that time, first, the total shear force that is the sum of the shear force Qr applied to the RC portion by the lever action and the shear force Qs applied to the S portion and the shear force Qe applied to the joint portion 13 by the seismic force. Qall is calculated (total shear force calculation step S109-1). That is, in the total shearing force calculation step S109-1, the total shearing force which is the sum of the shearing force applied by the bending moment acting on the joint part 13 and the shearing force acting on the joint part 13 by the load in the substantially horizontal direction is calculated. Calculate.

  After calculating the total shearing force Qall, next, the specification of the joint part 13 is selected (joint part specification selecting step S109-2). In this step S109-2, specifications such as the diameter, material, and pitch of the shear reinforcement are mainly selected as the specifications of the joint portion 13. That is, in the above-described step S108-2, the specification of the lap length L is selected as the specification of the joint portion 13, but in this step S109-2, the diameter of the shear reinforcement that becomes the fluctuation factor of the shearing force Select materials, pitch, and other specifications.

  When the specification selection of the joint portion 13 is completed, the shear strength of the internal reinforced concrete portion 15 in the joint portion 13, that is, the internal RC portion, and the shear strength of the steel pipe 18 are calculated (shear strength calculation step S109-3). Specifically, the ultimate shear strength Qus and the short-term allowable shear strength Qas of the steel pipe 18 and the ultimate shear strength Qur and the short-term allowable shear strength Qar of the RC portion are calculated to appropriate values with reference to academic standards and the like. In the flow chart shown in FIG. 9, steps S109-2 and S109-3 are performed after step S109-1 for calculating the total shear force. However, steps S109-1, S109-2 and S109-3 are performed. May be performed simultaneously. That is, the total shear force Qall, the shear strength of the internal RC portion in the joint portion 13 and the shear strength of the steel pipe 18 may be calculated simultaneously.

  After calculating the total shear force Qall, the shear strength of the internal RC portion, and the shear strength of the steel pipe 18, it is next examined whether the total shear force Qall is within the allowable range of the shear strength of the internal RC portion (internal Reinforced concrete partial shear force examination step S109-4). Specifically, whether or not the total shearing force Qall is smaller than the ultimate shearing strength Qur of the RC part at the final time is examined, and whether or not the total shearing force Qall is smaller than the short-term allowable shearing capacity Qar of the RC part at the shortest time. Consider whether or not.

  If it is determined in step S109-4 that the total shear force Qall is within the range of the ultimate shear strength Qur of the internal RC portion or the short-term allowable shear strength Qar, then the shear of the steel pipe portion where the total shear force Qall is an allowable value. It is examined whether it is within the range of proof stress (steel pipe shearing force examination step S109-5). Specifically, it is examined whether the total shearing force Qall is smaller than the ultimate shear strength Qus of the steel pipe 18 at the final time, and whether the total shearing force Qall is smaller than the short-term allowable shear strength Qas of the steel pipe 18 at a short time. Consider whether or not.

  Thus, in this embodiment, since the shear force of the steel pipe part and internal RC part in the design value of the joint part 13 determined temporarily is also examined, it is reconfirmed whether the said design value is an optimal value. Can be designed to a more suitable specification.

  In this embodiment, when it is determined in steps S109-4 and S109-5 that the calculated value is outside the range of the allowable value, when the specification is selected from the joint portion, Compare the cost of redoing specification selection.

  Specifically, when it is determined in step S109-4 that it is not within the range of the shear strength of the internal RC portion that is an allowable value, the specification of the component that becomes the variation factor of the shear force of the joint portion 13 is selected. A cost is compared between the case of redoing and the case of redoing from the specification selection of the lap length L of the joint part 13 (step S109-6). Then, if it is determined that the cost has been reduced from the specification selection of the constituent elements that will be the variation factor of the shear force of the joint portion 13, the process returns to step S109-2 and the variation factor of the shear force of the joint portion 13 is determined again. Redo the process from selecting the component specifications.

  On the other hand, if it is determined that the cost of re-starting from the specification selection of the lap length L of the joint portion 13 in step S109-6 is lower, then the specification selection of the lap length L of the joint portion 13 is restarted. The cost of the case and the case of starting over from the specification selection of the steel pipe winding part is compared. And it returns to the process (process 105 or process S108-2) which redoes the direction determined to be low.

  Moreover, when it determines with it not being in the range of the shear strength of the steel pipe part used as an allowable value in process S109-5, when it re-dos from specification selection of the lap length L of the joint part 13, and a steel pipe winding part Compare the costs when restarting from specification selection. And it returns to the process (process 105 or process S108-2) which redoes the direction determined to be low.

  Thus, in this embodiment, after examining the necessary cost for eliminating the defect of the designed joint part 13, the design can be re-designed from a more suitable process. For this reason, the validity of the design value of the joint portion 13 is examined, and when it is determined that the design value is not valid, the design can be started again from a more suitable process. The value can be designed more efficiently.

  Although each embodiment of the present invention has been described in detail as described above, it is easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. It will be possible. Therefore, all such modifications are included in the scope of the present invention.

  For example, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. Also, the configuration of the cast-in-place pile design system and the operation of the cast-in-place pile design method are not limited to those described in the embodiments of the present invention, and various modifications can be made.

DESCRIPTION OF SYMBOLS 10 Pile head steel pipe winding cast-in-place concrete pile (place cast pile), 11 Pile body, 11a Pile head, 12 Steel pipe concrete part, 13 Joint part, 14 Reinforced concrete part, 15 Internal reinforced concrete part, 16 Main reinforcement, 16a Upper end part, 18 steel pipe, 18b lower part, 20 internal concrete (internal structure part), 100 (placed pile) design system, 101 computer, 102 storage unit, 104 storage medium, 106 RAM, 108 ROM, 110 CPU (calculation unit), 112 Setting unit (bending stress setting unit, shear force setting unit), 114 determination unit (bending stress determination unit, shear force determination unit), 116 determination unit (joint part specification determination unit), 120 input unit, 122 output unit, 124 communication Part, 125 system bus, 126 Internet, S108 bending moment Discussion process, S108-6 balance examination process, S108-7 stress calculation process, S108-8 tolerance examination process, S108-9 specification selection cost comparison process, S109 shear force examination process, S109-1 total shear force calculation process, S109-2 Joint part specification selection process, S109-3 Shear strength calculation process, S109-4 Internal reinforced concrete partial shear force examination process, S109-5 Steel pipe shear force examination process, S109-6 Specification selection cost comparison process, S110 Test ratio examination Process

Claims (9)

It is a design method of a cast-in-place pile in which a reinforced concrete part and a steel pipe concrete part provided thereabove are integrated,
Examining the bending moment in the joint part where the internal reinforced concrete part in the reinforced concrete part including the upper end part of the reinforcing bar extending from the reinforced concrete part toward the inside of the steel pipe concrete part overlaps the steel pipe of the steel pipe concrete part Including the bending moment examination process,
The bending moment examination step
The inner peripheral surface of the steel pipe of the joint section through the internal reinforced concrete portion of the joint section due to a bending moment generated in the cast-in-place pile when a load in a substantially horizontal direction acts on the upper part of the cast-in-place pile. And calculating the balance relation between the compressive stress acting between the outer peripheral surface of the inner reinforced concrete portion and the tensile stress of the steel pipe acting in the opposite direction to the compressive stress, and then compressing the compressive stress and the tensile stress. And a balance examination step for calculating a relational expression between the concentrated load acting on the inner peripheral surface of the steel pipe in the joint section by the bending moment,
A stress calculating step for calculating the compressive stress and the tensile stress, respectively, based on the relational expressions calculated by the balancing examination step;
A cast-in-place pile design method comprising: a tolerance examination step for examining whether or not each of the compressive stress and the tensile stress is within a predetermined tolerance range. After the bending moment examination step, further includes a shear force examination step for examining the shear force in the joint part,
The shear force examination step
A total shearing force calculating step for calculating a total shearing force which is a sum of a shearing force applied by the bending moment acting on the joint part and a shearing force acting on the joint part by the load in the substantially horizontal direction;
An internal reinforced concrete partial shear force examination step for examining whether or not the total shear force is within an allowable range of shear strength of the internal reinforced concrete portion of the joint portion;
The cast-in-place pile design method according to claim 1, further comprising: a steel pipe shear force examination step for examining whether or not the total shear force is within an allowable range of the shear strength of the steel pipe of the joint portion. . The shear force examination step
Joint part specification setting process for setting the diameter, material, and pitch of the shear reinforcement in the joint part,
A shear strength calculation step for calculating a shear strength of the inner reinforced concrete portion of the joint portion and a shear strength of the steel pipe of the joint portion in the specification set in the joint portion specification setting step, respectively. The cast-in-place pile design method according to claim 2.   Among the allowable value examination step, the internal reinforced concrete partial shear force examination step, and the steel pipe shear force examination step, in the step where the verification ratio indicating the ratio of the calculated value to the allowable value in these steps is maximized, the verification ratio The cast-in-place pile design method according to claim 2, further comprising a verification ratio examination step for examining the validity of the cast pile.   When it is determined that the calculated value in the tolerance examination step, the internal reinforced concrete partial shear force examination step, and the steel pipe shear force examination step is outside the range of the tolerance, or in the examination ratio examination step The method further comprises a specification selection cost comparison step of comparing the specification selection of the joint portion or the specification selection cost of the steel pipe winding portion on which the steel pipe is attached when it is determined that the ratio is not appropriate. Item 5. A method for designing a cast-in-place pile according to item 4.   In the allowable value examination step, as the predetermined allowable value, either the standard strength of the steel pipe and the concrete filled in the steel pipe at the final design or the standard strength of the steel pipe and the concrete at the short-term design is used. The cast-in-place pile design method according to any one of claims 1 to 5, characterized in that   A design program for causing a computer to execute the cast-in-place pile design method according to any one of claims 1 to 6.   A storage medium that stores a computer-readable design program for causing a computer to execute the cast-in-place pile design method according to any one of claims 1 to 6. A cast-in-place pile design system in which a reinforced concrete part and a steel pipe concrete part provided thereabove are integrated,
Predetermined data related to the design of the cast-in-place pile including at least soil soil data on which the cast-in-place pile is provided, specification data relating to components of the cast-in-place pile, and past design performance data of the cast-in-place pile A storage unit for storing;
Based on at least the predetermined data and the bending moment in the joint portion where the internal reinforced concrete portion in the reinforced concrete portion and the steel pipe of the steel pipe concrete portion overlap, including the upper end portion of the rebar extending from the reinforced concrete portion to the steel pipe concrete portion. Calculating a desired design value of the length of the joint, and considering the validity of the design value, and determining a specification of the joint,
The computing unit is
A bending moment setting part for setting a bending moment in the joint part;
A shear force setting part for setting a shear force in the joint part;
A bending moment determination unit that examines the validity of the bending moment in the joint portion;
A shear force determination unit that examines the validity of the shear force of the steel pipe and the internal reinforced concrete portion in the joint portion;
Based on at least the determination results of the bending moment determination unit and the shear force determination unit, a joint unit specification determination unit that determines the specifications of the joint unit , and
The bending moment determination unit is configured to cause an inner peripheral surface of the steel pipe in the joint section and an outer peripheral surface of the internal reinforced concrete portion through the inner reinforced concrete portion of the joint section having the length by the bending moment. After calculating a balanced relational expression between the compressive stress acting in between and the tensile stress of the steel pipe acting in the opposite direction to the compressive stress, the compressive stress, the tensile stress, and the bending moment of the joint section are calculated. After calculating a relational expression with the concentrated load acting on the inner peripheral surface of the steel pipe, calculating the compressive stress and the tensile stress while examining the balance between the compressive stress and the tensile stress, setting the place pile compressive stress and the tensile stress, respectively, wherein Rukoto which have a function to consider whether within a predetermined tolerance System.