JP2003268787A - Support structure for concrete foundation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support structure for a concrete foundation capable of economically preventing a deterioration in durability due to corrosion of core steel arranged in a junction between the concrete foundation and a pile in regard to a support structure for a concrete foundation supporting the concrete foundation in a mounted state on the pile. <P>SOLUTION: The support structure S for the concrete foundation supporting a footing foundation (the concrete foundation) 20 in the mounted state on the cast-in-place pile 10 is characterized by that a core reinforcement (the core steel) 30 is arranged in the junction between the footing foundation 20 and a pile head part 11 of the cast-in-place pile 1, and rustproofing is applied in a minimum range necessary for preventing corrosion of the core reinforcement 30 in a junction neighborhood in a surface of the core reinforcement 30. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for supporting a concrete foundation with piles. 2. Description of the Related Art Conventionally, as shown in FIG. 3, a supporting structure 50 for supporting a footing foundation 20 '(concrete foundation) by a cast-in-place pile 10' has been used.
In general, a large amount of reinforcing steel 30 'is arranged at the joint of 0' and rigidly joined. On the other hand, with the progress of research in recent years, the analysis of the relationship between the state of the load and the stress acting on the joint between the footing foundation 20 ′ and the cast-in-place pile 10 ′ has been advanced, and the ground condition, the load condition, or the construction target As a result, it is often the case that a portion that does not necessarily need to be rigidly joined at a joint portion is clarified at the design stage. Therefore, as shown in FIG. 2, the applicant attaches the footing foundation 20 to the pile head 11 of the cast-in-place pile 10.
On the support structure S ′ for supporting the two pieces 20 and 10 with the edges thereof cut off, and have reached practical use. The supporting structure S ′ is formed by a core steel material 30 arranged at a joint between the footing foundation 20 and the cast-in-place pile 10.
It is possible to effectively resist the pulling force generated between the footing foundation 20 and the cast-in-place pile 10. [0003] However, in the conventional support structure S ', the footing foundation 20 and the cast-in-place pile 10 are not provided.
Are joined with their edges cut off, so that both 20 and
10 when a pull-out force is generated during 10
A gap is formed at the joint between the zero and the cast-in-place pile 10. At this time, groundwater, rainwater or seawater (hereinafter, referred to as “water”) existing around the support structure S ′ infiltrates from a gap formed in the joint, directly affects the core steel material 30, and By penetrating into the concrete from 40 and affecting the core steel material 30, the core steel material 30 is corroded and the durability of the support structure S 'is reduced. There has been a problem that S 'cannot be adopted. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and a support structure for a concrete foundation supporting a concrete foundation on a pile is provided. It is an object of the present invention to provide a concrete foundation support structure that can economically prevent a decrease in durability due to corrosion of a core steel material arranged at a joint. [0005] In order to solve the above-mentioned problems, a support structure for a concrete foundation of the present invention (hereinafter referred to as a "support structure") is provided.
"Support structure") is a concrete foundation support structure that supports a concrete foundation mounted on a pile. In the support structure, a core steel material is arranged at the joint between the concrete foundation and the pile head. The rust prevention treatment is applied to the minimum area necessary for preventing corrosion of the core steel material in the vicinity of the joint on the surface of the core steel material. Here, in the present invention, the minimum range necessary to prevent the core steel material from being corroded includes a range (for example, an error 10c) which may vary due to a construction error.
m). In addition, mounting means that the concrete foundation is merely placed on the bearing portion when the concrete foundation is supported, and that both edges are cut off. A concave is formed at the bottom of the concrete foundation, and the concrete foundation is supported with the pile head inserted into the concave, and the uneven part that transmits horizontal force between the concrete foundation and the pile Is not an obstacle to the supporting type of mounting. The type of the pile is not limited, and a cast-in-place pile, a steel pipe pile formed by filling concrete in a hollow portion of a steel pipe, or the like can be used. [0007] Further, the rust-preventive treatment is to apply a rust-preventive coating (for example, resin coating with epoxy resin, hot-dip galvanized, polymer resin, polymer cement resin, etc.) on the surface of the core steel material, or to perform rust-preventive treatment. Means for arranging a core steel material via the provided joint member. According to the present invention, in the support structure of the concrete foundation, a part of the surface of the core steel is subjected to a rust-preventive treatment to effectively prevent corrosion of the core steel. Therefore, the support structure of the concrete foundation can be adopted even in a place where water or the like is present in the surroundings. Further, the construction can be performed economically as compared with the case where the entire core steel material is subjected to rust prevention treatment. Here, a method of determining a rust prevention treatment range for determining a range in which rust prevention treatment is performed on a core steel material will be described. First,
When the support structure of the concrete foundation has passed a predetermined period, a range inside the concrete neutralized from the joint surface between the concrete foundation and the pile is calculated, and based on the neutralized range. A method for determining the rust-prevention treatment range for determining the range in which the rust-prevention treatment of the core rebar is performed will be described. [0010] Usually, in concrete in which steel materials are arranged, the steel materials are protected from corrosion by the alkalinity contained in the concrete, but the alkalinity of the concrete is lost due to the carbon dioxide gas in the air over time. This phenomenon is the neutralization of concrete, and when water or the like permeates into the neutralized concrete, the steel material is easily corroded. Therefore, it is preferable to calculate the range in advance and perform rust prevention treatment. . It has been found that the range of the interior of the concrete that is neutralized from the surface of the concrete is determined based on the period of use of the concrete, the water-cement ratio, and the neutralization rate. For example, when the water-cement ratio is 60% or more, it is calculated by substituting a predetermined condition into the following equation 1, and when the water-cement ratio is 60% or less, the predetermined condition is added to the following equation 2. Can be calculated by substituting the "
SS5 Reinforced concrete work ”). ## EQU1 ## ## EQU2 ## Incidentally, the neutralization ratio in the formulas 1 and 2 means that the ratio of water cement using ordinary Portland cement is 6%.
It is a ratio of the neutralization depth to the neutralization depth of concrete of 0% and slump of 18 cm, and is a numerical value determined corresponding to various types of concrete materials. According to the method for determining a rust-preventive treatment range, a part of the surface of the core steel is subjected to rust-preventive treatment corresponding to a range of the inside of the concrete neutralized from the joint surface between the concrete foundation and the pile. Therefore, corrosion of the core steel material can be more effectively and economically prevented. Next, when the support structure of the concrete foundation has passed a predetermined period, a range of the inside of the concrete where salt penetrates from the joint surface between the concrete foundation and the pile is calculated. A method for determining a rust-prevention treatment range for determining a range in which rust-prevention treatment of a core steel material is performed based on a permeation range will be described. When the concrete foundation support structure is constructed in the ocean or in the vicinity of the ocean, corrosion tends to progress when seawater having a high salt concentration comes into contact with the core rebar 30. Therefore, this range is calculated in advance to prevent corrosion. It is preferable to perform a rust treatment. The range of the inside of the concrete where the salt penetrates from the surface of the concrete is determined based on the service period of the concrete, the diffusion coefficient of the salt, the salt concentration on the concrete surface, and the critical salt concentration of the concrete. ing. For example, the salt content on the concrete surface is given by the following equation 3.
In order to penetrate into the concrete according to Fick's law shown in the above, by substituting predetermined conditions into the following equation 4, which is the solution of equation 3, it is possible to calculate the depth of the inside of the concrete where the salt penetrates (“ Building construction standard specifications and commentary JASS5 Reinforced concrete construction ”). [Equation 3] [Equation 4] The salt diffusion coefficient in the equation (3) is a coefficient using the water-cement ratio of concrete and temperature as parameters, and is a numerical value appropriately determined according to the concrete material and construction environment. In addition, the critical salt concentration in Equation 4 is defined as a concentration at which, when the salt concentration exceeds the critical salt concentration, corrosion occurs in the steel material inside the concrete, and damage such as cracking occurs in the concrete. It is 1.2 kg / m ³ . According to this method for determining the rust-preventive treatment range, a part of the core steel can be rust-prevented in accordance with the range of the inside of the concrete where salt penetrates from the joint surface between the concrete foundation and the pile. Even when seawater having a high salt concentration exists around the support structure, corrosion of the core steel material can be effectively and economically prevented. The corrosion of the core steel by the chemical substance and the corrosion of the core steel by the potential difference between the core steel and the ground are as follows.
The scope of the rust prevention treatment of the core steel material is determined by investigation, experiment, etc. Embodiments of the present invention will now be described.
The support structure for supporting the footing foundation with the cast-in-place pile will be described as an example with reference to the drawings. FIG. 1 is a view showing a support structure for a concrete foundation according to the present invention. FIG. 1 (a) is a side sectional view, and FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a). An embodiment of the support structure S of the present invention will be described. As shown in FIG. 1, the cast-in-place pile 10 is
And the lower end reaches the support layer (not shown) of the ground G. On the other hand, a pile head 11 of the cast-in-place pile 10 is in contact with the bottom of the footing foundation 20, and a support structure S that supports the footing foundation 20 in a state of being placed on the cast-in-place pile 10 is formed. . In the support structure S, even when a horizontal force acts on the footing foundation 20 and the cast-in-place pile 10, the two members 20 and 10 are not restrained from moving vertically and horizontally and rotating from each other. Because footing basics 20
In addition, it is possible to prevent an excessive sectional force from being generated in the cast-in-place pile 10, and rationality of design and easiness of construction are secured. The footing foundation 20 and the cast-in-place pile 1
At the joint with zero, a plurality of core reinforcing bars 30 (core steel) fixed near the center of the cross section of the pile head 11 are provided.
By arranging the core reinforcing bar 30, the pull-out force generated between the footing foundation 20 and the cast-in-place pile 10 can be effectively resisted, and the core reinforcing bar 30 is located near the center of the cross section of the pile head 11. Since it is fixed, transmission of the bending moment by the core reinforcing bar 30 can be reduced. Further, the surface of the core reinforcing bar 30 near the joint surface 40 between the footing foundation 20 and the cast-in-place pile 10 is calculated by the following method for determining a rust preventive processing range in order to prevent the core reinforcing bar 30 from corroding. An anticorrosion treatment for applying an anticorrosion paint 31 containing an epoxy resin or the like is applied to the predetermined area. Next, a method of determining a rust prevention treatment range for determining a range in which the rust prevention treatment of the core reinforcing bar 30 is performed will be described. Here, corrosion of the core reinforcing bar 30 is likely to occur near the joint surface 40 between the footing foundation 20 and the cast-in-place pile 10. this is,
A gap is formed at the joint between the footing foundation 20 and the cast-in-place pile 10 due to the pulling force generated between the two, and the water or the like penetrating into the gap directly affects the core rebar 30 and the joint surface. By penetrating into the concrete from 40 and affecting the core rebar 30, the core rebar 3
0 is corroded. Normally, the core rebar 30 is protected from corrosion by the alkalinity contained in the concrete, and is not corroded by water or the like that has penetrated into the concrete. In the case of penetration of the like, the core rebar 30 is easily corroded. Therefore, it is necessary to perform rust prevention treatment on the surface of the core rebar 30 corresponding to the range of the inside of the concrete neutralized from the joint surface 40. Further, when seawater or the like having a high salt concentration exists around the support structure S, it is necessary to perform rust prevention treatment on the surface of the core reinforcing bar 30 corresponding to the range of the inside of the concrete where the salt penetrates from the joint surface 40. . Usually, rust prevention treatment is performed on the surface of the core reinforcing bar 30 in the vicinity of the joint surface 40. However, a range in which the neutralization inside the concrete or the effect of salt penetrating into the concrete on the core reinforcing bar 30 is concerned. When the area is large, it is necessary to accurately determine the range in which the rust prevention treatment is performed as follows. First, a method of determining the rust-prevention processing range of the core reinforcing bar 30 based on the range of the inside of the concrete neutralized from the joint surface 40 will be described. The use period of the support structure S is determined in advance, and when the use period elapses, the joining surface 40
The depth inside the concrete neutralized from the following equation 5
Alternatively, the surface of the core rebar 30 corresponding to the above-mentioned depth from the joint surface 40 is set as the rust-prevention processing range by calculation using Expression 6. The depth inside the concrete to be neutralized is calculated by the following equation 5 when the water-cement ratio is 60% or more, and is calculated by the following equation 6 when the water-cement ratio is 60% or less. ("Building Construction Standard Specifications and Commentary JASS
5 Reinforced concrete work ”). [Equation 5] (Equation 6) Next, a method for determining the rust-prevention treatment range of the core reinforcing bar 30 based on the range of the inside of the concrete where the salt penetrates from the joint surface 40 will be described. When the same use period as when calculating the neutralized range has elapsed,
The depth of the inside of the concrete where the salt permeates from the joint surface 40 is calculated, and the core reinforcing bar 3 corresponding to the depth from the joint surface 40 is calculated.
The surface of 0 is the rust prevention treatment range. Since the salt on the concrete surface penetrates into the concrete according to Fick's law shown in the following equation 7, the depth of the concrete in which the salt penetrates is calculated by the following equation 8 which is a solution of the equation 7 (“ Architectural standard specifications and commentary JASS5
Reinforced concrete work ”). [Mathematical formula-see original document] [Equation 8] Then, on the surface of the core rebar 30, the range of the rust prevention treatment based on the neutralization inside the concrete and the range of the rust prevention treatment based on the permeation of the salt into the concrete are determined to be larger. The rust prevention treatment is performed by applying the rust prevention paint 31 within the range. The predetermined range is expanded or reduced (error 10) from the calculated range due to construction errors.
cm). Thereby, corrosion of the core rebar 30 is effectively prevented, and lowering of the durability of the support structure S is economically prevented. As described above, an example of a preferred embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and the design of each of the above-described components can be appropriately changed without departing from the spirit of the present invention. In particular,
It goes without saying that the dimensions, materials, arrangement, etc. of each element are appropriately determined according to the construction object. For example, the pile for mounting the footing foundation 20 is not limited to the cast-in-place pile 10, and other types of piles such as a steel pipe pile formed by filling concrete in a hollow portion of a steel pipe are used. Is also good. According to the support structure for a concrete foundation of the present invention, in a support structure for a concrete foundation supporting a concrete foundation in a state of being mounted on a pile, a part of a core steel material is rustproofed. By performing the treatment, to effectively prevent corrosion of the core steel material, the durability of the support structure is economically prevented from lowering, and even in a place where water or the like is present in the surrounding area,
The support structure of the concrete foundation can be adopted. In addition, the range of rust prevention treatment may be determined in response to the neutralization of the inside of the concrete and the penetration of salt into the inside of the concrete. By performing the treatment in the minimum range necessary to prevent the rust, the rust prevention treatment of the core steel material can be performed more effectively and economically. The minimum range includes a range that may change due to a construction error.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a support structure for a concrete foundation of the present invention, wherein (a) is a side sectional view, and (b) is A in FIG. 1 (a).
It is -A sectional drawing. 2A and 2B are side sectional views showing a conventional concrete foundation support structure, wherein FIG. 2A is a side sectional view, and FIG.
It is BB sectional drawing of. 3A and 3B are side sectional views showing a conventional concrete foundation support structure, wherein FIG. 3A is a side sectional view, and FIG.
It is CC sectional drawing of. [Description of Signs] S Supporting structure (supporting structure for concrete foundation) 10 Cast-in-place pile 11 Pile head 20 Footing foundation 30 Core rebar (core steel material) 31 Rust prevention paint 40 Joint surface

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Shinichiro Kawamoto             1-25-1, Nishi Shinjuku, Shinjuku-ku, Tokyo Taisei             Construction Co., Ltd. (72) Inventor Toshiyuki Hayashi             1-25-1, Nishi Shinjuku, Shinjuku-ku, Tokyo Taisei             Construction Co., Ltd. F term (reference) 2D041 AA01 AA02 BA37 DA03 DB02                 2D046 CA04

Claims (1)

Claims: 1. A concrete foundation supporting structure for supporting a concrete foundation mounted on a pile, wherein a core steel material is provided at a joint between the concrete foundation and a pile head. Concrete, characterized in that rust prevention treatment is applied to a minimum area required to prevent corrosion of the core steel material in the vicinity of the joint on the surface of the core steel material. Built-in support structure.