JP6967476B2 - Joining structure, how to build a joining structure - Google Patents

Description

The present invention relates to a bonded structure of a structure and a method for constructing the same.

At the joint between a pile made of general reinforced concrete and the foundation skeleton, the reinforcing bar extending from the pile is buried in the concrete of the foundation skeleton to integrate the pile and the foundation skeleton.

However, when the pile and the foundation skeleton are rigidly joined in this way, an excessive horizontal force is transmitted from the foundation skeleton to the pile head in the event of an earthquake, leading to damage to the pile. Therefore, by cutting the edge between the pile and the foundation frame at the joint and providing a sand-like sliding material (for example, Patent Document 1) or providing a sphere as a rolling bearing (for example, Patent Document 2), the pile head is formed. Measures have been proposed to prevent excessive horizontal force from acting.

Japanese Unexamined Patent Publication No. 2013-224535 Japanese Unexamined Patent Publication No. 2000-220151

At present, there is a demand for a structure having higher slip performance as such a joint. For example, in Patent Document 1, a sand-like body is provided between the pile and the foundation skeleton, but it is desirable to devise a device for further improving the sliding performance.

It is also desirable that the joint has a simple structure. For example, Patent Document 2 aims to reduce the horizontal force due to the rolling of a sphere, but the sphere, the fluid, and an accommodating body for accommodating the sphere and the fluid are required.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a joint structure having high sliding performance and a simple structure.

The first invention for solving the problems described above, a structure for joining the lower structure and its upper structure is pile or pillar, between the lower structure and the upper structure, prior SL upper A sliding layer that slides on the structure or the substructure is provided , and the sliding layer is formed by spraying graphite powder on the concrete and the concrete that is continuously provided with the substructure. It is a joint structure characterized by having a graphite powder layer continuously formed with concrete.

In the present invention, by providing a sliding layer having a reduced friction coefficient by containing graphite having solid lubricity between the upper structure and the lower structure, it is transmitted between the upper structure and the lower structure. The effect of reducing the horizontal force can be obtained. In the present invention, by providing a sliding layer utilizing the lubricity of the graphite material itself, it is possible to realize a bonded structure having a high sliding performance and a simple structure, and the above-mentioned structure including a sphere as a rolling bearing is also possible. It is unnecessary and low cost.

Further, in the present invention , the horizontal force reducing effect can be obtained by applying the self-lubricating concrete containing graphite as the sliding layer.

It is desirable that the concrete is a fine aggregate in which the fine aggregate having a particle size corresponding to the particle size of the graphite powder is replaced with the graphite powder.
As a result, it is possible to realize concrete having a low coefficient of friction while maintaining the strength of the concrete.

It is desirable that the upper structure or the reinforcing bar extending from the lower structure is embedded in the sliding layer, and the rust preventive layer is provided in the portion of the reinforcing bar in the sliding layer.
This makes it possible to enhance the integrity of the upper structure or the lower structure and the sliding layer. At this time, if the graphite of the sliding layer comes into contact with the reinforcing bar, it may rust, so that it is possible to form a rust preventive layer on the reinforcing bar to prevent rusting.

Further, in the present invention, a high horizontal force reducing effect can also be obtained by spraying graphite powder to form a graphite powder layer.

The second invention is a method for constructing a structure for joining the lower structure is pile or pillar and its upper structure, between the lower structure and the upper structure, prior SL upper structure or the lower A sliding layer that slides is provided on the structure, and the sliding layer is continuously provided with the lower structure and is continuously provided with the concrete containing graphite and spraying graphite powder on the concrete. graphite powder layer formed, a method for constructing a joint structure according to claim Rukoto to have a.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a joint structure or the like having high sliding performance and a simple structure.

The figure which shows the joint structure 1. The figure which shows the construction method of the joint structure 1. The figure which shows the construction method of the joint structure 1. The figure which shows the joint structure 1'. The figure which shows the joint structure 1a. The figure which shows the construction method of the joint structure 1a. The figure which shows the construction method of the joint structure 1a. The figure which shows the dynamic two-axis slide apparatus 100. The graph which shows the result of the friction coefficient measurement test.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
(1. Joining structure 1)
FIG. 1 is a diagram showing a joining structure 1 according to an embodiment of the present invention. As shown in the figure, the joint structure 1 of the present embodiment joins the pile 3 which is a lower structure and the foundation skeleton 5 which is an upper structure, and is between the concrete pile 3 and the foundation skeleton 5. A graphite concrete 7 and a graphite powder layer 9 are provided. The graphite concrete 7 and the graphite powder layer 9 form a sliding layer 4.

Graphite concrete 7 is concrete containing graphite and is a solid layer having self-lubricating property. The graphite concrete 7 is placed on the pile head 3a and provided integrally with the pile 3. The pile head 3a may be roughened to form irregularities to enhance the integrity of the pile 3 and the graphite concrete 7.

Graphite concrete 7 may be used, for example, in the preparation stage of ordinary concrete using ordinary aggregate, in which a part or all of the fine aggregate is replaced with graphite powder, or graphite powder is simply added to the preparation of ordinary concrete (with fine aggregate). It can be manufactured by adding (without replacement), then injecting water and kneading with cement, admixture, etc. Alternatively, after the production of ordinary concrete (ready-mixed concrete), graphite powder may be added to the ordinary concrete later and kneaded. At that time, graphite powder may be added together with an admixture or the like.

When replacing the fine aggregate with graphite powder, the fine aggregate is sifted to remove the fine aggregate having a particle size corresponding to the particle size of the graphite powder, and this is replaced with the graphite powder. By leaving the aggregate as it is without replacing it, it is possible to add self-lubricating property to the concrete while maintaining the strength of the concrete. At this time, the concrete (graphite concrete) does not have a fine aggregate having a particle size corresponding to the particle size of the graphite powder, and a fine aggregate having another particle size exists.

The graphite powder layer 9 is a layer made of a single graphite powder. For example, immediately after placing the graphite concrete 7, the graphite powder is sprayed on the graphite concrete 7, and the graphite powder is pressed with a trowel to be integrated with the graphite concrete 7. Is formed in. Since the graphite powder is integrated with the graphite concrete 7, it does not roll like a sphere, and the sliding layer 4 slides with respect to the foundation skeleton 5.

Reinforcing bars 11 can be provided between the pile 3 and the foundation skeleton 5. The lower end of the reinforcing bar 11 is embedded in the pile head 3a, and the portion above the lower end of the reinforcing bar 11 extends from the pile head 3a and is embedded and fixed in the graphite concrete 7 of the sliding layer 4. One or a plurality of reinforcing bars 11 are arranged.

When the graphite of the sliding layer 4 comes into contact with the reinforcing bar 11, the reinforcing bar 11 may rust. However, in the present embodiment, the rust preventive layer 13 is formed around the portion inside the sliding layer 4 of the reinforcing bar 11. Therefore, the reinforcing bar 11 can be prevented from rusting. As a method for forming the rust preventive layer 13, it is conceivable to wrap a tape or a rubber sheet around the reinforcing bar 11, apply a rust preventive material, an epoxy resin, or gypsum to the reinforcing bar 11, or perform hot-dip galvanizing the reinforcing bar 11. However, the method of forming the rust preventive layer 13 is not limited to this.

31 and 33 in FIG. 1 are the reinforcing bars of the pile 3, and are the main bar and the band bar of the pile 3, respectively. In the present embodiment, the same rust preventive layer 15 as the rust preventive layer 13 is provided on the top of the main bar 31 exposed on the pile head 3a.

(2. Construction method of joint structure 1)
2 and 3 are diagrams showing a method of constructing the joint structure 1. In this embodiment, an example of joining the pile 3 (existing pile) of the existing skeleton to the new foundation skeleton 5 after dismantling the existing skeleton will be described.

That is, in the present embodiment, first, as shown in FIG. 2A, the existing skeleton above the pile 3 is disassembled. The upper view of FIG. 2A is a view of the pile 3 from above, and the lower figure is a view of a vertical cross section of the pile 3. The same applies to FIGS. 2 (b) and 2 (c) thereafter.

The dotted line portion in FIG. 2A shows the disassembled existing skeleton. In the present embodiment, the main bar 31 of the pile 3 buried in the existing skeleton is also cut, and the top of the main bar 31 is exposed to the pile head 3a.

After dismantling the existing skeleton in this way, the lower end portion of the reinforcing bar 11 is embedded in the concrete of the pile head 3a as shown in FIG. 2 (b). At this time, for example, an insert (not shown) is embedded in the pile head 3a, and the lower end portion of the reinforcing bar 11 is attached to the insert.

Then, as shown in FIG. 2C, a rust preventive layer 13 is formed around the reinforcing bar 11 to perform a rust preventive treatment. In the present embodiment, the same rust preventive layer 15 as the rust preventive layer 13 is formed on the top of the main bar 31 exposed on the pile head 3a. It is also possible to omit the reinforcing bar 11, and in this case, it is only necessary to form the rust preventive layer 15 on the top of the main reinforcing bar 31.

Next, as shown in FIG. 3A, the formwork 20 is arranged and the graphite concrete 7 is placed on the pile head 3a. Then, as shown in FIG. 3B, immediately after the graphite concrete 7 is placed, the graphite powder is sprayed on the graphite concrete 7 and suppressed by a trowel to provide the graphite powder layer 9 integrated with the graphite concrete 7.

After that, the formwork 20 is disassembled, and the upper foundation skeleton 5 is newly constructed as shown in FIG. 3C to construct the joint structure 1.

As described above, in the present embodiment, the foundation skeleton is provided between the lower pile 3 and the upper foundation skeleton 5 by providing a sliding layer 4 having a reduced friction coefficient by containing graphite having solid lubricity. The effect of reducing the horizontal force transmitted between the pile 5 and the pile 3 can be obtained. In the present embodiment, by providing the sliding layer 4 utilizing the lubricity of the graphite material itself, a bonding structure 1 having a high sliding performance and a simple structure can be realized, and the above-mentioned sphere as a rolling bearing is included. The cost is low because no configuration is required.

In particular, in the present embodiment, the horizontal force reducing effect can be obtained by applying graphite concrete 7 containing graphite and having self-lubricating property as the sliding layer 4. Further, graphite concrete 7 can replace the mortar placing (leveling concrete) in the pile head treatment.

Further, in the present embodiment, by further providing the graphite powder layer 9 on the surface of the graphite concrete 7, a higher horizontal force reducing effect can be obtained.

In the graphite concrete 7, among the fine aggregates, the fine aggregate having a particle size corresponding to the particle size of the graphite powder is replaced with the graphite powder, and the fine aggregates having other particle sizes are left as they are, so that the strength of the concrete, etc. It is possible to impart self-lubricating property to concrete while maintaining the above.

Further, in the present embodiment, the reinforcing bar 11 can enhance the integrity of the sliding layer 4 and the foundation skeleton 5. Rust may occur when the graphite of the sliding layer 4 comes into contact with the reinforcing bar 11, but in the present embodiment, rusting can be prevented by forming the rust preventive layer 13 on the reinforcing bar 11. As shown in the joint structure 1'in FIG. 4, the reinforcing bars 11 may be arranged so as to penetrate the sliding layer 4 and the upper end thereof may be embedded in the foundation skeleton 5, and between the pile 3 and the foundation skeleton 5. The tensile force can be borne by the reinforcing bar 11 of the above. When the reinforcing bar 11 is buried, the total shear yield stress of the reinforcing bar 11 is set to be less than or equal to the frictional force (particularly dynamic frictional force) generated between the sliding layer 4 and the foundation frame 5, and the sliding performance of the sliding layer 4 is not hindered. To do so.

However, the present invention is not limited to this. For example, it is possible to omit the graphite powder layer 9 and form the sliding layer only with the graphite concrete 7.

On the other hand, it is also possible to use ordinary concrete instead of graphite concrete 7 and form a sliding layer only with the graphite powder layer 9, which also makes it possible to obtain a bonded structure having high sliding performance and a simple structure. .. However, a vertical force is always acting between the pile 3 and the foundation skeleton 5, and a horizontal force may be exerted by vibration, so that the graphite powder may be worn. In this respect, the graphite concrete 7 is more preferable. ..

Further, instead of the graphite powder layer 9, a liquid layer containing graphite powder or graphite molded into a sheet can be used, and it can be installed in the same manner as the graphite powder layer 9. Further, the pile 3 is not limited to the concrete one, but may be made of wood.

The joint structure 1 of the present embodiment is a joint of the pile 3 which is a lower structure and the foundation skeleton 5 which is an upper structure, and it is possible to reduce the horizontal force applied to the pile 3, but the lower structure. Is not limited to the pile 3, but may be a pillar, and the superstructure may be a beam or the like. In this case, by providing the same sliding layer as described above, the effect as a seismic isolation member can be obtained, and the horizontal force applied to the column can be reduced.

Further, it is also possible to provide a sliding layer 4 made of graphite concrete 7 or the like on the lower surface of an upper structure such as a foundation frame 5 or a beam. In this case, the sliding layer 4 is provided for a lower structure such as a pile 3 or a column. Glide. Further, the reinforcing bar 11 may be provided so as to extend from the superstructure and may be embedded in the graphite concrete 7 of the sliding layer 4.

Hereinafter, another example of the present invention will be described as a second embodiment. The second embodiment will be described with respect to the differences from the first embodiment, and the same points will be omitted by the same reference numerals in the drawings and the like.

[Second Embodiment]
(1. Joining structure 1a)
FIG. 5 is a diagram showing a joint structure 1a according to a second embodiment of the present invention. The joining structure 1a of the present embodiment also joins the pile 3 which is a lower structure and the foundation skeleton 5 which is an upper structure, and slides between the pile 3 and the foundation skeleton 5 by the graphite concrete 7 and the graphite powder layer 9. The layer 4 is provided, but the main difference is that the reinforcing bar 11 is not provided.

(2. Construction method of joint structure 1a)
6 and 7 are diagrams showing a method of constructing the joint structure 1a. This embodiment is an example of constructing a joint structure 1a between the pile 3 and the foundation skeleton 5 after constructing a new pile 3.

That is, in the present embodiment, first, as shown in FIG. 6A, a pile 3 made of cast-in-place concrete is constructed. FIG. 6A is a view of the vertical cross section of the pile 3. The same applies to the subsequent FIGS. 6 (b) (c) and 7 (a) (b).

Next, as shown in FIG. 6B, pile head treatment is performed to remove excess concrete. Then, as shown in FIG. 6 (c), the formwork 20 is arranged, the graphite concrete 7 is placed on the pile head 3a, and the graphite powder layer 9 is placed on the graphite concrete 7 as shown in FIG. 7 (a). prepare. The graphite concrete 7 is integrated with the pile 3 due to the unevenness of the concrete surface of the pile head 3a after removing the surplus concrete. Before placing the graphite concrete 7, a step of forming irregularities on the pile head 3a may be separately performed.

After that, the formwork 20 is disassembled, and the upper foundation skeleton 5 is constructed as shown in FIG. 7B to construct the joint structure 1a.

Also in this embodiment, a joining structure 1a having high sliding performance and a simple structure can be obtained, and the same effect as that of the first embodiment can be obtained. In this embodiment as well, it is possible to provide the reinforcing bar 11 as in the examples of FIGS. 1 and 4 of the first embodiment, and in this case as well, the reinforcing bar 11 is provided with the same rust preventive layer as in the first embodiment. Form around.

Hereinafter, the results of conducting a friction coefficient measurement test and examining the horizontal force reducing effect of graphite will be described as an example. The present invention is not limited to this.

<Graphite powder>
The graphite powder was added to concrete as shown in Examples 1 to 4 described later. In addition, as a comparative example, we also examined ordinary concrete that does not use graphite powder.

<Example 1>
In Example 1, in the compounding stage before water injection of ordinary concrete, graphite powder in a surface dry state is used instead of a part of the fine aggregate, and the graphite concrete produced by this is poured into a mold and cured. A test piece for the material test and a test piece for the friction coefficient measurement test, which will be described later, were prepared in. The specimen is a cylinder with a diameter of 100 mm and a height of 200 mm, and the specimen is a cylinder with a diameter of 100 mm and a height of 100 mm.

The fine aggregate replaced with the graphite powder was a fine aggregate having a particle size in the same range as the particle size of the graphite powder, and the fine aggregates having other particle sizes were used as they were.

<Example 2>
In Example 2, in the compounding stage before water injection of ordinary concrete, graphite powder in a surface dry state was used instead of all the fine aggregates, and the graphite concrete produced thereby was used to test specimens and test specimens in the same manner as described above. Was produced.

<Example 3>
In Example 3, after the production of ordinary concrete (ready-mixed concrete), the specimen and the test piece were prepared in the same manner as above by the graphite concrete produced by adding the graphite powder in an air-dried state afterwards and kneading it by hand. ..

<Example 4>
In Example 4, ordinary concrete (ready-mixed concrete) was produced, and immediately after the concrete was placed in a mold, an air-dried graphite powder was sprayed on the top surface thereof to prepare a test piece and a test piece.

<Comparison example>
As a comparative example, a test piece and a test piece were prepared from ordinary concrete in the same manner as described above. The formulation of ordinary concrete of Examples 1 to 4 (for Examples 1 and 2 the formulation of ordinary concrete when the fine aggregate is not replaced with graphite powder) is also a comparative example except for the amount and type of admixture used. It is almost the same as ordinary concrete, and for example, the water-cement ratio is the same between Examples 1 to 4 and Comparative Example. The same applies to environmental conditions such as kneading temperature and curing method.

<Physical characteristics of each concrete>
Material tests were performed on concrete specimens of 1 day, 7 days, and 28 days of age prepared in Examples 1 to 4 and Comparative Examples, and the compressive strength, electrostatic modulus, and Poisson's ratio were measured.

In Examples 1 and 2, it was difficult to remove the mold at the age of 1 day. Therefore, in Example 1, the specimen at the age of 2 days was used instead of the specimen at the age of 1 day. In Example 2, the measurement with the specimen of the material age of 1 day was omitted. Further, for each of Examples 1 to 4 and Comparative Example, the number of specimens of each material age was set to 3, and the average values of the compressive strength, the static elastic modulus, and the Poisson's ratio were calculated among the specimens.

As a result, the specimens of Examples 1 to 4 tended to have lower compressive strength than the specimens of Comparative Example. However, it was found that the compressive strength of the specimens of Examples 1, 3 and 4 in which the amount of graphite powder was relatively small was about 80% of that of the specimens of Comparative Example, and the strength was maintained. Similar trends were seen for Poisson's ratio and static elastic modulus.

<Friction coefficient measurement test>
Next, a friction coefficient measurement test was conducted using the concrete test pieces prepared in Examples 1 to 4 and Comparative Example. In Examples 1, 3, 4 and Comparative Example, three test pieces were prepared, and the friction coefficient described later is the average value thereof. Further, in each test piece of Example 4, the amount of graphite powder sprayed is changed.

(Dynamic 2-axis slide device)
The dynamic 2-axis slide device 100 shown in FIG. 8 was used for the friction coefficient measurement test. In this dynamic two-axis slide device 100, the frame 101 is provided with a vertical moving portion 103 that moves in the vertical direction along the rail 102 and a horizontal moving portion 105 that moves horizontally along the rail 104.

In the friction coefficient measurement test, the test piece 200 was placed on the stage 106 provided in the horizontal moving part 105, and the steel plate 108 was placed between the pressing part 107 provided in the vertical moving part 103 and the test piece 200. While applying a constant axial force to the test piece 200 by the pressing portion 107, the horizontal moving portion 105 is gradually moved in the horizontal direction, and when the horizontal load does not increase (horizontal rigidity (= horizontal load ÷ horizontal displacement)). The horizontal load (sliding load) at (when it became 0) was measured. The above axial force was constant for all test specimens. The coefficient of friction can be obtained by dividing the sliding load by the above axial force.

(Experimental result)
FIG. 9 is a graph showing the relationship between the horizontal load and the horizontal displacement of the test pieces of Examples 1 to 4 and Comparative Example. In this graph, the vertical axis is the friction coefficient conversion value obtained by dividing the horizontal load by the axial force, and the horizontal axis is the amount of horizontal displacement.

As shown in FIG. 9, the friction coefficient of the test piece of the comparative example (the value converted into the friction coefficient of the horizontal load when the horizontal rigidity becomes approximately 0) was about 0.5, whereas the friction coefficient of Examples 1 to 4 was about 0.5. It was found that the coefficient of friction of the test piece was low and that it had the effect of reducing the horizontal force as a sliding layer.

In particular, the test pieces of Examples 1 and 2 have a friction coefficient of about 0.2 to 0.25, and the test piece of Example 4 has a friction coefficient of about 0.15, and Example 3 (friction coefficient is about 0.4) after addition of graphite powder. ), The frictional force was greatly reduced. In the test piece of Example 4, no difference in the coefficient of friction was observed depending on the amount of graphite powder sprayed.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

1, 1', 1a: Joint structure 3: Pile 3a: Pile head 5: Foundation frame 7: Graphite concrete 9: Graphite powder layer 11: Reinforcing bar 13, 15: Rust prevention layer 20: Formwork 31: Main bar 33: Band bar 100: Dynamic 2-axis slide device 200: Specimen

Claims (3)

It is a joint structure of a substructure that is a pile or a column and its superstructure.
Between the lower structure and the upper structure, the sliding layer to slide provided for before Symbol superstructure or the lower structure,
The sliding layer has a concrete containing graphite, which is continuously provided with the substructure, and a graphite powder layer formed continuously with the concrete by spraying graphite powder on the concrete. Characterized joint structure. Junction structure of claim 1, rebar extending from the upper structure or the lower structure is embedded in the sliding layer, characterized in that the anticorrosive layer is provided on portions of the sliding layer of the reinforcing bar .. It is a method of constructing a joint structure between a substructure that is a pile or a column and its superstructure.
Between the lower structure and the upper structure, the sliding layer to slide provided for before Symbol superstructure or the lower structure,
The sliding layer, the provided continuously with the lower structure, that Yusuke and concrete containing graphite, and a graphite powder layer is continuously formed with the concrete by dispersing graphite powder on said concrete A method for constructing a bonded structure, which is characterized by the fact that.

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