JP6840457B2 - Reinforcement method for single column structures - Google Patents

Description

The present invention relates to a method for reinforcing a single column structure having a pile foundation in which one column is supported by one pile.

The electricity generated at the power plant of the electric power company is transmitted through the transmission line stretched (supported) by the steel tower built on the ground, and after being substationed at the substation, it is supplied to the customer. Towers that support transmission lines (transmission towers) mainly include square towers composed of four main pillars and steel pipe single-column towers composed of one steel pipe (column) (for example, patents). Document 1).

In a steel pipe single column tower, an anchor bolt and an anchor frame for fixing the anchor bolt generally form a fixing portion. Then, it is designed so that the fixing portion in the foundation formed of concrete, mortar, or the like is fixed at the place where the steel pipe single column steel tower is arranged. In particular, in Patent Document 1, one pillar is supported by one pile placed in the ground as a foundation. Such pile foundations are also called single pile foundations.

Japanese Unexamined Patent Publication No. 2012-87616

Steel pipe single-column towers are superior to square towers in terms of landscape and reduction of the tower site area, but they are subject to a larger bending moment when wind pressure or seismic motion acts than square towers. For this reason, an axial force is generated in the anchor bolt due to the load generated by bending, and shear fracture or split fracture (hereinafter, these are referred to as damage) may occur in the foundation from there.

In order to prevent damage to the foundation of the steel pipe single-column tower (hereinafter referred to as a single-column structure) described above, it is necessary to reinforce the fixing portion so as to reduce the axial force generated in the anchor bolt. As a method of reinforcing the fixed portion, as described above, especially in a single column structure in which the foundation is a pile foundation, the fixed portion is wound and restrained with reinforced concrete, steel material, chemical fiber, etc. (freshly wound). Reinforcement) is common.

When performing the above-mentioned winding reinforcement, it is necessary to excavate the surrounding area because the anchorage part is located in the ground in the single column structure. Therefore, when the single-column structure is located in an urban area, it may be difficult to secure a construction site. In addition, if the foundation is reinforced by winding it up, the width of the foundation will increase, so it will be necessary to secure new land, and there will be a problem that the cost for purchasing additional land will increase.

In view of such a problem, the present invention can eliminate the need for large-scale construction such as excavation, secure the construction site, and purchase additional land, and greatly increase the cost required for the reinforcement work. The purpose is to provide a method for reinforcing a single column structure that can be reduced.

In order to solve the above problems, a typical configuration of the method for reinforcing a single column structure according to the present invention is a pile foundation in which one column is supported by one pile and a pile foundation protruding upward from the pile foundation. A single-column structure that has an anchor bolt fixed to the pillar and a flange-shaped anchor frame provided at the bottom of the column, and the column is fixed to the pile foundation by fastening the anchor bolt to the anchor frame. The reinforcing method is characterized in that the reinforcing reinforcing bars are fixed on the upper part of the pile foundation so as to project upward, and concrete is cast on the pile foundation so as to bury the reinforcing reinforcing bars and the anchor frame.

According to the above configuration, the pile foundation is reinforced by fixing the reinforcing reinforcing bars on the upper part of the pile foundation and placing concrete on the pile foundation. Therefore, since large-scale construction such as excavation around the pile foundation is not required, it is not necessary to secure a construction site. Moreover, since the repair work is carried out only on the upper part of the pile foundation, the width of the pile foundation does not increase and it is not necessary to purchase additional land. Therefore, according to the above configuration, it is possible to greatly reduce the cost required for the reinforcement work of the single column structure while simplifying the work.

The reinforcing bar may be fixed in a hole drilled in the upper part of the pile foundation. According to such a configuration, the reinforcing reinforcing bar can be fixed to the pile foundation by inserting the reinforcing reinforcing bar into the hole formed by drilling the pile foundation with a core drill or the like. Since the drilling is smaller than the construction such as excavation, there is less noise and it is possible to reduce the burden on the neighboring residents during the construction.

The reinforcing bar may be connected to the pile main reinforcing bar exposed by scraping the upper part of the pile foundation. When the fixing portion is on the ground, by connecting the reinforcing bar and the pile main reinforcing bar in this way, it is possible to further increase the reinforcing strength and reduce the reinforcing cost.

The concrete placed on the pile foundation should have the same width as the pile foundation. As a result, there is little change in the appearance of the single column structure near the foundation before and after reinforcement. That is, since the thickness of the foundation of the single column structure does not change, the visual oppressive feeling can be reduced.

The reinforcing bar may protrude above the anchor frame. When a column receives a bending moment, the anchor frame and anchor bolt (hereinafter referred to as the anchoring part when both of them are included), which are the bases of the column, are subjected to compressive stress on one side and tensile stress on the other side. It takes. At this time, the anchor frame tends to move upward on the side where the tensile stress is applied. Therefore, by projecting the reinforcing bar above the anchor frame, the tensile stress can be effectively received by the reinforcing bar. It is preferable that the reinforcing reinforcing bar extends from the end of the anchor frame to an extension line of 45 degrees.

According to the present invention, it is possible to eliminate the need for large-scale construction such as excavation, secure the construction site, and purchase additional land, and it is possible to significantly reduce the cost required for the reinforcement work. It becomes possible to provide a method for reinforcing a single column structure.

It is a figure which illustrates the single column structure to be reinforced by the reinforcement method of this embodiment. It is a figure explaining the reinforcement method of the single column structure of this embodiment. It is a figure explaining another example of the reinforcement method of the single column structure of this embodiment. It is a figure explaining the load applied to a single column structure. It is a figure explaining the effect by the reinforcement method of the single column structure of this embodiment.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in such an embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are not shown. To do.

FIG. 1 is a diagram illustrating a single column structure 100 to be reinforced by the reinforcing method of the present embodiment. As illustrated in FIG. 1, the single-pillar structure 100 to be reinforced by the reinforcing method of the present embodiment includes one pillar 110 on which a power transmission line (not shown) is stretched and one such pillar 110. It has a pile foundation 120 supported by a book pile. Anchor bolts 132a and 132b are fixed to the pile foundation 120 so as to project upward from the foundation 120. On the other hand, a flange-shaped anchor frame 134 is provided below the pillar 110. Then, by fastening the anchor bolts 132a and 132b to the anchor frame 134, the pillar 110 is supported by the pile foundation 120.

FIG. 2 is a diagram illustrating a method of reinforcing the single column structure 100 of the present embodiment. In the reinforcement method of the present embodiment, first, holes 122a and 122b are drilled in the single column structure 100 shown in FIG. 1 at the upper part of the pile foundation 120 as shown in FIG. 2A. Then, as shown in FIG. 2B, the reinforcing bars 140a and 140b are inserted into the holes 122a and 122b drilled in the upper part of the pile foundation 120. As a result, the reinforcing bars 140a and 140b are fixed to the upper part of the pile foundation 120 so as to project upward. The reinforcing bars 140a and 140b can be fixed to the pile foundation 120 by using mortar, chemical anchors, or the like.

When drilling holes 122a and 122b in the upper part of the pile foundation 120, for example, a core drill or the like can be used. Since the drilling is smaller than the construction such as excavation, there is less noise and it is possible to reduce the burden on the neighboring residents during the construction.

After fixing the reinforcing bars 140a and 140b as shown in FIG. 2B, the hoop reinforcing bars 142 are arranged around the reinforcing bars 140a and 140b. Then, as shown in FIG. 2C, concrete 150 is placed on the pile foundation 120 so as to bury the reinforcing bars 140a and 140b and the anchor frame 134. As a result, the fixing portions (anchor frame 134 and anchor bolts 132a and 132b) of the single column structure 100 are reinforced. At this time, the concrete 150 to be cast on the pile foundation 120 may have the same width as the pile foundation 120. As a result, the thickness of the foundation of the single column structure 100 does not change before and after reinforcement. Therefore, the visual feeling of oppression can be reduced.

As described above, in the method of reinforcing the single column structure 100 of the present embodiment, the reinforcing bars 140a and 140b are fixed on the upper part of the pile foundation 120, and the concrete 150 is placed on the pile foundation 120 to fix the reinforcing bars. The part and the pile foundation 120 are reinforced. Since it is possible to reinforce the pile foundation 120 without excavating the periphery of the pile foundation 120 on a large scale, it is not necessary to secure a construction site.

Further, in the present embodiment, since the repair work is performed only on the upper part of the pile foundation 120, the width of the pile foundation 120 does not increase. Therefore, it is not necessary to purchase additional land around the single column structure 100. Therefore, according to the method for reinforcing the single-column structure 100 of the present embodiment, it is possible to greatly reduce the cost required for the reinforcement work of the single-column structure 100 while simplifying the reinforcement work.

FIG. 3 is a diagram illustrating another example of the method for reinforcing the single column structure 100 of the present embodiment. It should be noted that the description of the structure and the process overlapping with the reinforcing method described with reference to the single column structure 100 of FIG. 1 and FIG. 2 will be omitted.

In the reinforcement method illustrated in FIG. 3, first, as shown in FIG. 3A, the upper part of the pile foundation 120 is scraped to expose the pile main reinforcing bars 136a and 136b inside the pile foundation 120. Then, as shown in FIG. 3B, the reinforcing reinforcing bars 140a and 140b are connected to the exposed pile main reinforcing bars 136a and 136b. As a result, the reinforcing bars 140a and 140b are fixed on the upper part of the pile foundation 120. Hoop reinforcing bars 142 are arranged around the reinforcing reinforcing bars 140a and 140b. After that, as shown in FIG. 3C, concrete 150 is placed on the pile foundation 120 so as to bury the reinforcing bars 140a and 140b and the anchor frame 134.

According to the above configuration, it is possible to further increase the reinforcing strength by connecting the reinforcing bars 140a and 140b to the pile main reinforcing bars 136a and 136b while obtaining the same effect as the reinforcing method shown in FIG.

FIG. 4 is a diagram illustrating a load applied to the single column structure 100. In the reinforcing method of the present embodiment, concrete 150 is placed on the pile foundation 120 as shown in FIGS. 2 (b) and 3 (b). When a force is applied to the column 110 due to wind pressure or an earthquake, the anchoring portions (anchor frame 134 and anchor bolts 132a and 132b) at the base of the column 110 receive a bending moment A as shown in FIG. Then, compressive stress B is applied to one side (anchor bolt 132b side in FIG. 4) and tensile stress C is applied to the other side (anchor bolt 132a side in FIG. 4) of the fixing portion.

With respect to the compressive stress B, the concrete of the pile foundation 120 receives a load. On the side where the tensile stress is applied, the anchor frame 134 tends to move upward, but the anchor bolts 132a and the reinforcing bars 140a can be dispersed and receive the load. As a result, the tensile stress applied to the anchor bolt 132a can be reduced, and the splitting of the pile foundation 120 can be effectively suppressed.

It is preferable that the upper ends of the reinforcing bars 140a and 140b project above the anchor frame 134. When the anchor frame 134 has a plurality of flanges as shown in FIG. 4, it is preferable to project the anchor frame 134 above the upper flange. Further, it is preferable that the upper ends of the reinforcing bars 140a and 140b extend above the extension line L of 45 degrees from the end of the anchor frame 134. As a result, the tensile stress applied from the anchor frame 134 to the concrete 150 can be effectively received by the reinforcing reinforcing bar 140a.

FIG. 5 is a diagram illustrating the effect of the method of reinforcing the single column structure 100 of the present embodiment. In FIG. 5, Example 1 uses a reinforcing bar having a diameter of 19 mm to reinforce the single column structure 100, and Example 2 uses a reinforcing bar having a diameter of 22 mm to reinforce the single column structure 100. This is an example. Comparative Example 1 is the state in which the single column structure 100 is not reinforced, that is, the state shown in FIG. 1, and Comparative Example 2 is an example in which the pile foundation of the single column structure 100 is reinforced by conventional winding. .. The moment M on the vertical axis is the moment applied to the column 110 of the single column structure 100, and the rotation angle θ on the horizontal axis indicates the rotation angle (deformation amount) of the column 110 with respect to the pile foundation 120.

As shown in FIG. 5, in Comparative Example 1 in which the reinforcement is not performed, the single column structure 100 is gradually deformed as the stress is applied, and the yield point is the time when the stress of less than 1400 kN · m is applied. In Comparative Example 2 in which the conventional winding reinforcement is performed, the yield point when the stress is applied is the time when the stress is less than 1800 kN · m. From this, it can be understood that even the conventional winding reinforcement is effective against the deformation of the single column structure 100.

On the other hand, when the method for reinforcing the single column structure 100 of the present embodiment is applied, in Example 1 using the reinforcing bar having a diameter of 19 mm, the yield point is at the time of stress of about 2500 kN · m and the diameter is 22 mm. The yield point in Example 2 using the reinforcing reinforcing bars of the above is the time point of stress of 3000 kN · m. That is, while Comparative Example 1 can withstand a stress of less than 1400 kN ・ m and Comparative Example 2 can withstand a stress of less than 1800 kN ・ m, in Examples 1 and 2 in which the reinforcing method of the present embodiment is applied, those 1. It is possible to withstand 8 to 2.0 times the stress. From this, it can be understood that damage to the single column structure 100, particularly the pile foundation 120 thereof, can be suitably suppressed by applying the reinforcing method of the present embodiment.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood.

The present invention can be used as a method for reinforcing a single column structure having a pile foundation in which one column is supported by one pile.

100 ... Single column structure, 110 ... Column, 120 ... Pile foundation, 122a ... Hole, 122b ... Hole, 132a ... Anchor bolt, 132b ... Anchor bolt, 134 ... Anchor frame, 136a ... Pile main reinforcing bar 136b ... Pile main reinforcing bar , 140a ... Reinforcing bar, 140b ... Reinforcing bar, 142 ... Hoop reinforcing bar, 150 ... Concrete

Claims (4)

A pile foundation that supports one pillar with one pile,
Anchor bolts fixed so as to project upward from the pile foundation,
It has a flange-shaped anchor frame provided at the bottom of the pillar, and has.
In a method for reinforcing a single column structure in which the column is supported by the pile foundation by fastening the anchor bolt to the anchor frame.
Without winding and reinforcing the anchoring portion including the anchor bolt and the anchor frame,
Reinforcing bars are fixed in the holes drilled in the upper part of the pile foundation and protrude above the pile foundation.
A hoop rebar is placed around the reinforcing rebar,
A method for reinforcing a single column structure, which comprises placing concrete on the pile foundation so as to bury the reinforcing reinforcing bar and the anchor frame. A pile foundation that supports one pillar with one pile,
Anchor bolts fixed so as to project upward from the pile foundation,
It has a flange-shaped anchor frame provided at the bottom of the pillar, and has.
In a method for reinforcing a single column structure in which the column is supported by the pile foundation by fastening the anchor bolt to the anchor frame.
Without winding and reinforcing the anchoring portion including the anchor bolt and the anchor frame,
The upper part of the pile foundation is squeezed to expose the pile main reinforcing bar, the reinforcing reinforcing bar is connected to the pile main reinforcing bar, and the reinforcing reinforcing bar is projected above the pile foundation.
A hoop rebar is placed around the reinforcing rebar,
A method for reinforcing a single column structure, which comprises placing concrete on the pile foundation so as to bury the reinforcing reinforcing bar and the anchor frame. The method for reinforcing a single column structure according to claim 1 or 2, wherein the concrete to be cast on the pile foundation has a width equivalent to that of the pile foundation. The method for reinforcing a single column structure according to any one of claims 1 to 3, wherein the reinforcing reinforcing bar projects above the anchor frame.

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