JPH11311378A - Earthquakeproof flexible bent pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly absorb displacement without deviation even when the displacement is generated in the ground by an earthquake, etc., by heightening a load limit and saving a piping place in a structure. SOLUTION: A corrugated extensive part 15a to extend and contract along the shaft center direction is provided on a flexible bent pipe 14a, and as an interval (d) of corrugation 18a is made small as shown by d1 >d2 ...>d7 from a pipe bent part center 16a to a pipe end part 17a, the side of the pipe end part 17a is soft and easy to be deformed. Consequently, the flexible bent pipe 14a is connected to piping 1 fixed on the ground, etc., when displacement is caused by an earthquake, etc., on the ground, etc., the neighbourhood of the pipe end part 17a is easily deformed, deformation of the bent part center 16a deformation of which is the largest is restrained, deformation of the whole of the flexible bent pipe 14a becomes comparatively uniform, and deviation of deformation is attemperated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earthquake-resistant flexible tube connected to piping for various uses such as gas, electric power, and water.

[0002]

2. Description of the Related Art In many cases, the above-mentioned pipes are generally laid in a firmly supported building, a valve pit, an abutment, etc. (hereinafter referred to as an earthquake-resistant structure) and an area in the ground around the same. In general, elbows and bends are connected to the piping at the boundary of the area or inside the structure, avoiding places where other piping is laid, and earthquakes that occur on the ground at the elbows and bends etc. Absorb the displacement caused by
Prevents buckling of piping. When the above elbow, bend, etc. are subjected to bending action due to ground displacement due to earthquake, etc.,
As in the case of the bending action of a straight pipe with a curved section, local buckling does not occur, and the flattening phenomenon gradually progresses.

FIG. 8 is a side view showing an example of an elbow connected to a pipe extending over the area inside the earthquake-resistant structure and the ground.

The pipe 1 of the pipe 1 belonging to the seismic structure 5
a and the pipe 1 b of the pipe 1 belonging to the ground 4
Are connected via elbows 2a and 2b on the side. In the earthquake-resistant structure 5, the pipe 1 is penetrated and fixed to the wall 5a. 6 is the basis. In the ground 4, a pipe 1b belonging to the ground 4 is laid in a not-shown groove formed by excavating the ground 4, and is buried with a mountain sand 7 or the like. Reference numeral 8 denotes another pipe buried in the ground.

A connecting pipe 3 for adjusting the length is connected between the elbows 2a and 2b to connect the elbow 2b to the pipe 1b horizontally at a predetermined position.

On the other hand, in piping in a base-isolated structure such as a base-isolated building, it is necessary to reduce the relative displacement between the ground and the base-isolated structure due to an earthquake or the like. For example, flange connection using a thin bellows, A loop pipe using an elbow or the like is basically used.

FIG. 9 is a side view, partially in section, showing an example of piping in a conventional seismic isolation building, and FIG.
FIG. 3 is a sectional view taken along line A.

The lower part of the base-isolated building 9 is installed in the ground 4,
A base isolation mechanism 10 is provided between the base isolation building 9 and the foundation 6. A loop pipe 11 is laid in the lower part of the base-isolated building 9, and the pipe 1 c drawn from the ground 4 is connected to the loop pipe 11.
Of the elbow 12a. The pipe 1d fixed in the base-isolated building 9 is 12d of the loop pipe 11.
Is connected to one end. Reference numeral 13 denotes a valve.

In the case of a seismic isolation building 9, if an earthquake occurs and a large shaking indicated by a large arrow occurs due to ground displacement, the seismic isolation mechanism 1
Zero absorbs the shaking due to the ground displacement, and reduces the shaking of the base-isolated building 9 to a small shaking indicated by a small arrow. On the other hand, the pipes in the base-isolated building 9 are such that the pipe 1c is fixed to the ground 4, and the pipe 1d is fixed to the base-isolated building 9. And relative displacement.

However, since the loop pipe 11 is used,
The relative displacement is absorbed. Generally, the loop pipe 11 is configured by connecting many elbows so as to sufficiently absorb the above-described relative displacement. Here are four elbows 1
2a, 12b, 12c, and 12d are connected.

[0011]

However, the above-mentioned prior art has the following problems. The elbows 2a and 2b connected to the pipe shown in FIG. 8 have insufficient absorption of displacement of the pipe 1 generated in the ground 4 in the axial direction.
An elbow 2a connected between the tube 1a and the tube 1b,
2b tends to crack due to strain.

Also, with respect to the displacement generated in the ground 4 perpendicular to the axial direction of the pipe 1, the bending action is biased at the center of the curved portion of the elbows 2a, 2b, and the strain concentrates at that point, causing cracks. Therefore, the ability of the elbows 2a and 2b to absorb the displacement of the ground decreases.

On the other hand, in a pipe in a base-isolated structure such as a base-isolated building, a flange joint using a thin-walled bellows has a flange joint, so that the load limit is lower than that of a welded-integrated pipe, and the use of the pipe is limited. There is.

In the loop piping shown in FIGS. 9 and 10,
In order to sufficiently reduce the deformation and stress of the piping system due to the assumed relative displacement between the ground 4 and the base-isolated building 9, a considerably large loop is required, and a lot of space for the loop piping is required.

The same applicant has filed an application in which a curved pipe having a corrugated expansion / contraction part is used in place of an elbow connected to a pipe as shown in FIG. 8 (Japanese Patent Application No. 9-27583).
issue).

However, it is not enough to uniformly absorb the ground displacement without bias, and the present invention has been accomplished after further studies.

According to the present invention, the load limit is high, piping installation space can be saved, and even if the ground around an earthquake-resistant structure or a base-isolated structure (hereinafter simply referred to as a structure) is displaced by an earthquake or the like, the displacement can be reduced. An object of the present invention is to provide an earthquake-resistant flexible bent tube capable of uniformly absorbing displacement without bias.

[0018]

A first aspect of the present invention is an earthquake-resistant flexible bent pipe connected to a pipe, which is provided with a corrugated expansion / contraction section which extends and contracts along the axis of the pipe. A pipe-shaped earthquake-resistant flexible bent pipe characterized in that the interval between waveforms is reduced from the center of the bent portion to at least one end of the pipe.

A second aspect of the present invention is an earthquake-resistant flexible tube connected to a pipe, wherein a corrugated expansion / contraction portion is provided which extends and contracts along the axis of the tube. The ratio of the height to the width of the waveform is increased toward the end of the pipe.

A third aspect of the present invention relates to an earthquake-resistant flexible bent pipe connected to a pipe, provided with a corrugated expansion / contraction part extending and contracting along the axial direction of the pipe, wherein the corrugated expansion / contraction part is at least one from the center of the pipe bending part. A pipe-shaped earthquake-resistant flexible pipe characterized in that the interval between the waveforms is small and the ratio of the height to the width of the waveform is increased toward the end of the pipe.

According to the seismic flexible bent pipe of the present invention, when the pipe receives a displacement of the ground due to an earthquake or the like, the above configuration makes it possible.
Since the pipe end is softer than the center of the tube bend, it is greatly deformed by external force, and the deformation of the center of the tube bend becomes relatively small. Cracks can be eliminated, displacement can be absorbed uniformly, and the displacement absorbing ability can be improved.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side view showing an embodiment of the present invention. The flexible bent tube 14a is provided with a corrugated expansion / contraction portion 15a that expands and contracts along the axial direction thereof. The corrugated expansion / contraction portion 15a extends from the center of the tube bending portion 16a to the pipe end 17a to form a waveform 18a.
Is reduced, that is, d ₁ > d ₂ > d ₃ > d ₄ > d ₅
> D ₆ > d ₇ , the pipe end 17a side is softened so as to be easily deformed. Also, actually, d ₁ = d ₂ > d ₃ = d ₄
It is also possible to stepwise reduced _{as> d 5 = d 6 = d} 7.

The interval between the waveforms 18a can be reduced from the center of the bent portion 16a to one end 17a (for example, the side connected to the pipe fixed to the ground), and can be equal to the other end 17a. .

With the above configuration, the flexible curved pipe 14a is connected to the pipe 1 fixed to the ground or the like, and when the ground or the like is displaced by an earthquake or the like, the vicinity of the pipe end 17a is easily deformed. However, the deformation of the tube bent portion center 16a, which is the largest deformed portion, is suppressed, the deformation of the entire flexible bent tube 14a is relatively uniform, and the bias of the deformation is reduced. As a result, the center of the tube bending section 1
Since a crack due to local distortion is less likely to occur in 6a, its displacement absorbing ability is improved.

The flexible bent pipe 14a can be easily connected to the pipe by welding, and the load limit can be increased.

FIG. 2 is a schematic diagram showing a bending moment and a deformed state of the flexible bent tube of the present invention. Here, the pipe end is fixed to an earthquake-resistant structure or the like, and an external force indicated by an arrow acts on a point P on the pipe connected to the pipe end. (A) shows the state of the bending moment of the flexible tube, and (b) shows the state of the deformation of the flexible tube.

For comparison, a case where an elbow is used as a conventional example is compared with a case where a flexible curved tube having a corrugated expansion / contraction portion at a constant interval described in Japanese Patent Application No. 9-27583 is used. It is shown as an example.

In FIG. 1A, reference numeral 14 denotes a curved tube including a conventional elbow, a flexible tube of a comparative example, and a flexible tube of the present invention, and reference numeral 16 denotes a curved tube. Reference numeral 17 denotes a pipe end portion.

In FIG. 3 (b), the solid line shows the deformation of the flexible tube of the present invention, the dotted line shows the deformation of the flexible tube of the comparative example, and the two-dot chain line shows the deformation of the shaft center of the conventional elbow.

As is apparent from FIG. 2, the bending moment becomes maximum at the point Q in the center 16 of the tube bending portion.
In both the comparative example and the conventional example, the deformation is maximum at the tube bending center 16. However, the amount of deformation is in the order of Conventional Example> Comparative Example> Example of the present invention.

On the other hand, on the pipe end 17 side, the pipe end is denoted by R
, The amount of deformation near the pipe end is in the order of the present invention> comparative example> conventional example.

As a result, in the case of the conventional example, the center 1
In contrast, in the example of the present invention, the unevenness of the deformation at the tube bending center 16 is reduced.

That is, in the example of the present invention, by making the vicinity of the pipe end relatively soft, the deformation of the entire flexible bending pipe becomes relatively uniform, and the local bending at the center 16 of the pipe bending section. The generation of cracks due to strain can be greatly reduced, and the displacement absorbing ability can be improved.

FIG. 3 is a side view showing another embodiment of the present invention.
FIG. 4 is an enlarged view of a main part of FIG. Flexible tube 1
4b is a corrugated expansion and contraction portion 15b which expands and contracts along its axis.
Is provided, and the corrugated expansion / contraction portion 15b extends from the center of the tube bending portion 16b.
The height with respect to the width L of the waveform 18b over the pipe end 17b
h is increased, ie, t₁<T_Two<T_Three<T_Four<T _Five
<T₆<T₇To soften and deform the pipe end 17b side
Making it easier. Also, in practice, t₁= T_Two<T_Three= T_Four
<T_Five= T₆= T₇It can be gradually increased like
Wear.

With the above configuration, the flexible curved pipe 14b is connected to the pipe 1 fixed to the ground or the like, and when the ground or the like is displaced by an earthquake or the like, the vicinity of the pipe end 17b is easily deformed. However, the deformation of the tube bent portion center 16b, which is the largest deformed portion, is suppressed, the deformation of the entire flexible bent tube 14b is relatively uniform, and the bias of the deformation is reduced. As a result, the center of the tube bending section 1
Since cracks due to local strain hardly occur in 6b, the displacement absorbing ability is improved.

FIG. 5 is a side view showing another embodiment of the present invention. The flexible curved tube 14c is provided with a corrugated expansion / contraction portion 15c that expands and contracts along the axis of the flexible tube 14c.
The interval d of c is small, and the ratio t of the height h to the width L of the waveform 18c is increased. That is, d ₁ > d ₂ > d ₃ >
d ₄ > d ₅ > d ₆ > d ₇ , and t ₁ <t ₂ <t ₃ <t ₄ <t
_By setting ₅ <t ₆ <t ₇ <t ₈ , the tube end 17c side is further softened and further deformed. Also, in practice, d ₁
> D ₂ = d ₃ = d ₄ > d ₅ = d ₆ = d ₇ , and gradually reduced, t ₁ = t ₂ <t ₃ = t ₄ = t ₅ <t ₆ = t ₇ = t ₈
In this way, the size can be increased stepwise.

With the above configuration, the flexible curved pipe 14c is connected to the pipe 1 fixed to the ground or the like, and when the ground or the like is displaced by an earthquake or the like, the vicinity of the pipe end 17c is easily deformed. However, the deformation of the tube bending portion center 16c where deformation is greatest is suppressed, the deformation of the entire flexible bending tube 14c is relatively uniform, and the bias of deformation is reduced. As a result, the center of the tube bending section 1
Since a crack due to local distortion is less likely to occur in 6c, its displacement absorbing ability is improved.

FIG. 6 is a side view having a partial cross section showing an embodiment in which the flexible bent pipe of the present invention is connected to a pipe, and FIG. 7 is a cross sectional view taken along line BB of FIG. . 9 and 10
The same reference numerals are used for the portions common to and the description is omitted.

The pipe 1d of the pipe 1 belonging to the seismic isolation building 9
And the pipe 1c of the pipe 1 belonging to the ground 4 are connected via two flexible bent pipes 14a. 6 is the basis. A tube 1e is connected between the two flexible bent tubes 14a.

In this case, even if the ground 4 is displaced by an earthquake or the like on the side of the pipe 1c fixed to the ground 4, the flexible bent pipe 14a
Can absorb the displacement.

In the case where the pipe occupies less space and performs the same function as compared with the conventional loop pipe, the flexible bent pipe 14a of the present invention does not require a loop pipe, so that about 1 / 4 saves space.

The same effect can be obtained by using the above-described flexible tubes 14b and 14c instead of the flexible tubes 14a.

[0044]

According to the flexible curved pipe of the present invention, even if the ground around the earthquake-resistant structure or the base-isolated structure is caused by an earthquake or the like, the displacement can be relatively uniformly absorbed, so that the efficiency is improved. Thus, the displacement absorbing ability can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a schematic view showing a state of a bending moment and a deformation amount of a flexible bent tube according to the present invention.

FIG. 3 is a side view showing another embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is a side view showing another embodiment of the present invention.

FIG. 6 is a side view with a partial cross section showing one embodiment when the flexible curved pipe of the present invention is connected to a pipe.

FIG. 7 is a sectional view taken along the line BB of FIG. 6;

FIG. 8 is a side view showing an example of a conventional elbow connected to a pipe extending over a region in a seismic structure and a region in the ground.

FIG. 9 is a side view having a partial cross section showing an example of a pipe in a conventional base-isolated building.

FIG. 10 is a sectional view taken along line AA of FIG. 9;

[Explanation of symbols]

Reference Signs List 1 pipe 1a, 1b, 1c, 1d, 1e pipe 2a, 2b elbow (conventional) 3 connection pipe 4 ground 5 seismic structure 5a wall 6 foundation 7 mountain sand 8 other pipe 9 seismic isolation building 10 seismic isolation mechanism 11 Loop piping 12a, 12b, 12c, 12d Elbow (loop piping) 13 Valve 14 Curved tube (including elbow, flexible curved tube, etc.) 14a, 14b, 14c Flexible curved tube 15a, 15b, 15c Waveform expansion / contraction portion 16, 16a , 16b, 16c Center of tube bending portion 17, 17a, 17b, 17c Tube end 18a, 18b, 18c Waveform d Interval t Ratio of height to width of waveform

Claims (3)

[Claims] 1. A seismic flexible bent tube connected to a pipe, provided with a corrugated expansion / contraction portion extending and contracting along an axial direction of the tube, wherein the corrugated expansion / contraction portion is at least one pipe end from the center of the pipe bending portion. A seismic flexible bent pipe, characterized in that the interval between the corrugations is reduced over time. 2. A seismic flexible bent tube connected to a pipe, provided with a corrugated expansion / contraction portion extending and contracting along the axial direction of the tube, wherein the corrugated expansion / contraction portion is at least one pipe end from the center of the pipe bending portion. Wherein the ratio of the height to the width of the corrugation is increased. 3. A flexible seismic flexible tube connected to a pipe, wherein a corrugated expansion / contraction part is provided which extends and contracts along the axis of the pipe, and the corrugated expansion / contraction part is at least one pipe end from the center of the pipe bend. , Wherein the interval between the waveforms is small and the ratio of the height to the width of the waveform is large.