JP2022124158A - Damping device - Google Patents

Abstract

To provide a damping device that improves earthquake resistance and safety of a liquid storage tank against a bulging phenomenon.SOLUTION: There is provided a damping device 1 arranged in a storage tank for liquid with a rectangular cross-sectional shape, including: a first fixing part 2 fixed to a first side S1 of an inner wall of the liquid storage tank; a second fixing part 3 fixed to a second side surface S2 in the liquid storage tank; and a connecting member 6 connecting the first fixing part 2 and the second fixing part 3, in which the first side S1 and the second side S2 are adjacent to each other, the first fixing part 2 and the second fixing part 3 having a hollow elastic member 4 and a support member 5 that supports the hollow elastic member 4, and the connecting member 6 connects the hollow elastic member 4 of the first fixing part 2 and the hollow elastic member 4 of the second fixing part 3.SELECTED DRAWING: Figure 2

Description

The present invention relates to a damping device arranged in a storage tank for liquids.

A sloshing phenomenon is known as a phenomenon in which liquid storage tanks such as water tanks are destroyed by seismic motion. The sloshing phenomenon is a phenomenon in which the seismic motion and the natural frequency of the liquid in the tank match, causing the liquid to sway greatly due to resonance, which damages mainly the ceiling and upper side panels of the tank.

Furthermore, an analysis of tank destruction caused by recent earthquakes reveals that tanks are destroyed not only by the above-mentioned sloshing phenomenon, but also by a phenomenon called bulging. The bulging phenomenon is a phenomenon in which the liquid in the tank vibrates as a mass (mass body) coupled with the panel on the side of the tank due to seismic motion. The hydrostatic pressure of a liquid in a tank is proportional to its depth, so it increases towards the bottom of the tank. Therefore, when the bulging phenomenon occurs, stress is likely to concentrate on the lower portion of the tank, increasing the risk of damage to the side panels and corners of the lower portion of the tank.

As a countermeasure against this bulging phenomenon, for example, a method of disposing a damping device as described in Patent Document 1 below in a liquid storage tank has been considered.

Japanese Patent Application Laid-Open No. 2020-117269

According to the damping device described in Patent Document 1, when the panels of the liquid storage tank tend to expand outward due to the bulging phenomenon, the kinetic energy is efficiently absorbed to prevent damage to the tank. Although it can be prevented, the effect of damping the kinetic energy is not necessarily sufficient for the behavior of the panel of the liquid storage tank inward, and there is room for improvement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a damping device that improves the seismic resistance and safety of liquid storage tanks against bulging phenomena.

The damping device of the present invention is a damping device disposed in a liquid storage tank having a rectangular cross-sectional shape,
a first fixing part fixed to a first side surface of an inner wall of the liquid storage tank; a second fixing part fixed to a second side surface inside the liquid storage tank; and the first fixing part and the second fixing part. Equipped with a connecting member that connects the part,
the first side and the second side are adjacent to each other;
The first fixing portion and the second fixing portion each include a hollow elastic member and a support member that supports the hollow elastic member,
The connecting member connects the hollow elastic member of the first fixing portion and the hollow elastic member of the second fixing portion.

According to this configuration, when kinetic energy due to seismic motion or the like is applied to the first side surface of the inner wall of the liquid storage tank, for example, when the first side surface swells outward or dents inward, the The first fixing part receives the kinetic energy, and the hollow elastic member of the first fixing part is elastically deformed. When the hollow elastic member is elastically deformed, resistance is generated and kinetic energy is converted into thermal energy, so vibration due to seismic motion or the like can be damped.

In addition, when kinetic energy due to seismic motion or the like is applied to the second side surface of the liquid storage tank, the kinetic energy is mainly applied to the second fixing portion as in the case of the first fixing portion. As a result, the hollow elastic member of the second fixing portion is elastically deformed to attenuate the vibration caused by seismic motion or the like.

That is, when kinetic energy due to seismic motion or the like is applied to both the first side surface and the second side surface of the inner wall of the liquid storage tank, the hollow elastic member of the first fixing portion and the hollow elastic member of the second fixing portion are elastically deformed to attenuate vibrations caused by seismic motion and the like.

Therefore, the kinetic energy due to seismic motion or the like is not concentrated in one hollow elastic member of the damping device, but is dispersed to two hollow elastic members, so that the vibration due to seismic motion or the like can be efficiently damped. As a result, the bulging phenomenon is weakened, so not only when the sides of the liquid storage tank bulge outward, but also when the sides of the liquid storage tank tend to collapse inward, the liquid storage tank is less likely to break.

In the present invention, it is preferable that the first side surface and the second side surface form four corners of the inner wall of the liquid storage tank.

According to this configuration, since the damping device is installed at the corner of the inner wall of the liquid storage tank, the installation method is easy, and the stress due to the bulging phenomenon is likely to concentrate at the corner. WHEREIN: The damage|damage can be prevented more effectively.

In the present invention, it is preferable that a plurality of stages are arranged vertically in the liquid storage tank.

According to this configuration, it is possible to more efficiently attenuate vibrations due to seismic motion and the like in a wider range in the vertical direction of the liquid storage tank, thereby weakening the bulging phenomenon.

In the present invention, the liquid storage tank is a panel type tank formed by joining a plurality of panels, the first fixing portion is fixed to the joint portion between the panels on the first side surface, and the second It is preferable if a fixing part is fixed to the joint between the panels on the second side.

When a bulging phenomenon occurs in a panel type tank, joints between panels may be damaged. However, according to this configuration, since the first fixing portion and the second fixing portion are fixed to the joint portion between the panels and the joint portion is reinforced, the joint portion is hardly damaged.

In the present invention, it is preferable that the hollow elastic member is made of a thermosetting elastomer or a thermoplastic elastomer.

As in this configuration, the hollow elastic member is made of a thermosetting elastomer or a thermoplastic elastomer, so that the hollow elastic member becomes more flexible and elastically deformable, and vibrations caused by seismic vibrations are more efficiently attenuated to prevent the bulging phenomenon. can weaken.

1 is a plan view of a storage tank for liquids with a damping device; FIG. 1 is a perspective view of a damping device; FIG. Fig. 2 is a side view of the damping device; FIG. 4 is a side view of another embodiment of a damping device; FIG. 4 is a side view of another embodiment of a damping device; FIG. 11 is a perspective view of another embodiment of a damping device; FIG. 11 is a perspective view of another embodiment of a damping device; 4 is a graph showing wall response displacement; 4 is a graph showing wall response displacement; 4 is a graph showing wall response acceleration; 4 is a graph showing wall response acceleration; 4 is a graph showing a rainflow analysis of wall displacement. 4 is a graph showing a rainflow analysis of wall displacement. 4 is a graph showing rainflow analysis of wall response acceleration; 4 is a graph showing rainflow analysis of wall response acceleration;

[Embodiment]
An embodiment of a damping device according to the present invention will be described based on the drawings.
(liquid storage tank)
The liquid storage tank T in the present invention means a general tank capable of accommodating and storing a storage liquid L such as water, fuel, chemical solution, etc. In addition, presence or absence of earthquake resistance is particularly related. not a thing

As a liquid storage tank T to which the damping device 1 according to the present invention can be applied, for example, a general box-shaped tank having a rectangular (square or rectangular) cross-sectional shape can be mentioned.

Although the form of the tank is not particularly limited, for example, a panel type tank composed of a plurality of panels P as shown in FIG. Examples of such panel-type tanks include known stainless panel tanks having a plurality of stainless steel panels and known FRP panel tanks having a plurality of fiber reinforced plastic (FRP) panels.

The size of the tank is not particularly limited, for example, from a tank equivalent to a general water receiving tank such as 3m in height x 3m in width x 3m in depth, or a large tank with an effective water depth exceeding 7m, for example. It can be applied to a wide range of applications.

(Attenuation device)
As shown in FIGS. 1 and 2, the damping device 1 according to the present embodiment includes a first fixing portion 2 fixed to the first side surface S1 of the inner wall of the liquid storage tank T, the inner wall of the liquid storage tank T and a connecting member 6 that connects the first fixing part 2 and the second fixing part 3 .

The first side S1 and the second side S2 of the inner wall of the liquid storage tank T are meant to be adjacent to each other. For example, in the case of the liquid storage tank T having a rectangular cross-sectional shape in this embodiment, the first side surface S1 and the second side surface S2 of the inner wall mean the side surfaces that are substantially perpendicular to each other in plan view.

On the other hand, if the cross-sectional shape of the liquid storage tank T is not rectangular, the first side surface S1 and the second side surface S2 of the inner wall are not necessarily perpendicular to each other in plan view. That is, it does not mean that the damping device 1 of the present invention cannot be applied to tanks other than liquid storage tanks having a rectangular cross section.

Moreover, it is desirable that the first side surface S1 and the second side surface S2 form a corner portion C of the inner wall of the storage tank T for liquid.

In the present invention, the inner wall of the liquid storage tank T includes not only the side wall but also the ceiling and bottom. In addition, although the first side S1 is limited to the inner wall, the second side S2 is not limited to the inner wall, and other members provided in the liquid storage tank, for example, a plurality of vertical frames and a plurality of horizontal frames. It also includes a side surface such as a reinforcing member formed by combining with a jungle gym.

The first fixing part 2 and the second fixing part 3 in this embodiment have the same configuration, and include a hollow elastic member 4 and a support member 5 that supports the hollow elastic member 4 .

The hollow elastic member 4 in this embodiment is a cylindrical elastic member having a cross-sectional shape (see FIG. 3) that combines a semicircular portion and a rectangular portion, but is not limited to this configuration, and may be other configurations. Also, for example, a tubular shape having a simple circular or rectangular cross-sectional shape may be used.

Examples of the constituent material of the hollow elastic member 4 include, but are not limited to, thermosetting elastomers such as rubber, and thermoplastic elastomers such as olefin elastomers, styrene elastomers, and vinyl chloride resin elastomers. not something. However, for example, when the damping device 1 of the present invention is applied to a water receiving tank that stores tap water, it is necessary to use a material that does not adversely affect the quality of the tap water.

The hollow elastic member 4 can be manufactured by using the above constituent material as a material, for example, by molding it into an elongated plate shape by a known extrusion molding method, and then cutting it into a predetermined size and shape.

The support member 5 in this embodiment includes a hollow square tube 50 having a rectangular cross section and two angle members 51 having an L-shaped cross section. It is fixed by a bolt and a nut on each of the two sides on the side. The angle member 51 is formed with a plurality of through holes for inserting bolts, screws, and the like.

A curved surface forming a semi-circular cross-sectional portion of the hollow elastic member 4 is fixed to one long-side side surface of the cross-section of the square tube 50 of the support member 5 with bolts and nuts.

The connecting member 6 in this embodiment includes two plate-like members 60 and two L-shaped frame members 61 in plan view. It is fixed by welding.

Each of the two plate-like members 60 of the connecting member 6 faces the flat outer surface (surface opposite to the curved surface) of the hollow elastic member 4 in each of the first fixing portion 2 and the second fixing portion 3. , secured by bolts and nuts. Thereby, the hollow elastic member 4 of the first fixing portion 2 and the hollow elastic member 4 of the second fixing portion 3 are connected via the connecting member 6 .

The square tube 50 and the angle member 51 of the support member 5 described above, and the plate member 60 and the frame member 61 of the connection member 6 are desirably made of, for example, relatively lightweight aluminum, but are limited to this. not to be

(How to use the attenuation device)
Next, a method of using the damping device 1 according to this embodiment will be described. Here, an example in which a liquid storage tank T configured as a general box-shaped frame having a rectangular cross-sectional shape is used and the damping device 1 of the present embodiment described above is applied to the liquid storage tank T will be described. explain.

As shown in FIG. 1, the liquid storage tank T is constructed by combining a plurality of vertical frames and a plurality of horizontal frames to form a basket-like structure like a jungle gym. A panel P (inner wall) made of FRP or the like is attached.

The first side surface S1 and the second side surface S2 of the inner wall of the liquid storage tank T in this embodiment mean the side surfaces that are substantially orthogonal to each other in plan view.

As shown in FIGS. 1 and 2, at four corners C in plan view of the liquid storage tank T, the first damping device 1 is placed in such a posture that the axis of the hollow elastic member 4 is substantially horizontal. Each of the fixing part 2 and the second fixing part 3 is arranged at substantially the same height position with respect to the panel P forming the corner part C. As shown in FIG.

At this time, as shown in FIGS. 2 and 3, it is desirable to arrange the first fixing portion 2 and the second fixing portion 3 of the damping device 1 at the joint portion J between the panels P arranged in the vertical direction.

Then, by driving screws or the like into the through-holes of the angle members 51 of the first fixing portion 2 and the second fixing portion 3, the damping device 1 can be attached to the panel P forming the corner portion C of the liquid storage tank T. fixed to

The damping devices 1 are desirably provided at the four corners C in plan view of the liquid storage tank T, but the configuration is not necessarily limited to this.

The damping device 1 is desirably installed at a height where the amplitude of the panel P due to the bulging phenomenon is expected to be large. For example, it is preferable to install it below the middle of the liquid storage tank T in the vertical direction, and it may be installed not only in one stage but also in multiple stages in the vertical direction as shown in FIG.

According to the above configuration, when an earthquake occurs, the hollow elastic member 4 of the damping device 1 deforms, thereby attenuating the vibration caused by seismic motion or the like in the liquid storage tank T, thereby weakening the bulging phenomenon. As a result, it is possible to prevent the panels, frames, etc. of the liquid storage tank T from being deformed or damaged.

[Other embodiments]
1. The method of installing the damping device 1 on the panel of the liquid storage tank T is not limited to the above-described embodiment. The second fixing portion 3 may be provided with only one angle member 51, and may be fixed to the panel via only the angle member 51 (only the first fixing portion 2 is shown in FIG. 4 for convenience). Further, as shown in FIG. 5, the attenuation device 1 may be installed with a flat plate 52 interposed between each of the first fixing portion 2 and the second fixing portion 3 of the damping device 1 and the panel (in FIG. Only the first fixing part 2 is described for convenience). Incidentally, the flat plate 52 is desirably fixed so as to cross the joint portion J between the panels.

2. The installation method of the damping device 1 according to the present invention is not limited to the corner portion C of the inner wall of the storage tank T for liquid. Alternatively, for example, as shown in FIG. It may be fixed to the panel P. In this case, the side panel P is the first side S1 and the bottom panel P is the second side S2. Alternatively, for example, as shown in FIG. 7, the first fixing portion 2 of the damping device 1 is fixed to the panel P on the side wall of the liquid storage tank T, and the side surface of the reinforcing member R provided inside the liquid storage tank T is fixed. You may make it fix the 2nd fixing|fixed part 3 to. In this case, the side wall panel P becomes the first side surface S1, and the side surface of the reinforcing member R becomes the second side surface S2.

3. Although not shown, the configuration of the connecting member described above is not limited to the above-described embodiment. Alternatively, for example, a member having an isosceles trapezoidal shape in plan view may be used as the frame member. Also good.

4. A damping device according to the present invention may be used in combination with a known sloshing damper (vibration damping device) for suppressing the sloshing phenomenon for liquid storage tanks.

[About the demonstration experiment]
A demonstration experiment was conducted to confirm the effect of the damping device of the present invention.
In order to verify the effect of the damping device, a vibration experiment was conducted using an FRP water tank of 3000 mm x 3000 mm x 3000 mm.

Water was poured into this tank to a water level of 2700 mm at an internal capacity of 90%, which is the same as the normal set water level. As the bulging damping device used here, elastic deformation dampers mainly made of rubber were attached to the four corners of the water tank and eight positions at 1000 mm and 2000 mm from the bottom of the water tank. A comparison was made using seismic waves regarding the reduction effect of the side wall response acceleration of the water tank with and without the damping device.

Two types of seismic waves were used in this experiment, equivalent to 30% displacement of the JMA Kobe SN direction observation wave observed by the Kobe Marine Observatory during the Hyogoken Nanbu Earthquake and equivalent to 50% displacement of the Kumamoto Earthquake Uto NS direction observation wave. was excited orthogonally to the measurement plane. A large vibration device owned by Aichi Institute of Technology was used for the vibration experiment. In this experiment, the swelling direction of the water tank was positive (+), and the recessing direction was negative (-).

Experimental results (wall response displacement)
8 and 9 show the wall surface response displacement at the position of 1500 mm.
FIG. 8 shows the wall surface response displacement during excitation with Kobe SN of 30%. In the case of non-damping, the maximum displacement is 82.64 mm on the + side, whereas it is 53.12 mm when the damping device is added, which is reduced by about 36%. On the - side, the vibration was -75.76 mm when the vibration was not damped, while it was -60.72 mm when the damping device was added, a reduction of about 20%.

Further, FIG. 9 shows the wall surface displacement during excitation at 50% Kumamoto Uto NS. While the maximum displacement was 59.44 mm without damping, it was 30.88 mm with the damping device, which was reduced by about 48%. On the minus side, it is -69.36 mm when the vibration is not damped, and -43.20 mm when the damping device is added, which is about 38% less.

(Wall response acceleration)
10 and 11 show wall response acceleration at a position of 2000 mm.
Fig. 10 shows the wall response acceleration at Kobe SN 30% vibration, and the maximum acceleration in the case of non damping is 7.56 m/s2 on the + side and ^-7.60 m/s2 on the - ^side . be. When the damping device is added, the acceleration is 7.14 m/s ² on the + side and -6.67 m/s ² on the - side, and there is no significant change when compared with the maximum acceleration. However, it can be seen that by adding the damping device, the repeated acceleration can be suppressed, and the damping is accelerated after 5 seconds.

FIG. 11 shows the wall response acceleration at the Kumamoto earthquake Uto NS 50% excitation. The maximum acceleration on the + side was 6.46 m/s ^{2 without damping, and 4.45 m/s 2 with} the damping device. When compared with and without the damping device, it is reduced by about 29% of 1.92 ^m /s2. ^On the minus side, it is -7.25m/s2 without damping, and ^-6.91m /s2 with the damping device, a reduction of about ⁵ % from 0.35m/s2. stays in However, it can be seen that by adding the damping device, the repeated acceleration can be suppressed, and the damping is accelerated after 5 seconds.

(Rainflow analysis)
A rainflow analysis was conducted to clarify the damping effect of the wall response displacement and the wall response acceleration by adding the damping device. Rainflow analysis is usually used as a method to predict the fatigue life of machines and structures that receive irregular and repetitive fluctuating loads, and determines the amplitude that contributes to the fatigue life and the number of occurrences from the path of the raindrops. is. In this experiment, this method was applied to the wall displacement and acceleration, and the reduction effect accompanying the addition of the damping device was analyzed.

12 and 13 show the results of the rainflow analysis of the wall surface displacement. FIG. 12 is for Kobe SN with 30% excitation, and FIG. 13 is for Kumamoto Uto NS with 50% excitation. In FIG. 12, the number of occurrences of the total amplitude of 100 mm to 130 mm is 4.5 in the case of non-damping, but it is greatly reduced to 0.5 when the damping device is added. In FIG. 13 as well, the number of occurrences of the total amplitude of 80 mm to 120 mm is 5.5 when the vibration is not damped, but when the damping device is added, it is greatly reduced to 0 times. From this, it is considered that the effect of the damping device was exerted on the large amplitude.

On the other hand, FIGS. 14 and 15 show the results of rainflow analysis of wall response acceleration. FIG. 14 is for Kobe SN 30% excitation, and FIG. 15 is for Kumamoto Uto NS 50% excitation. In FIG. 14, the number of occurrences of 11 to 16 m/s ² is 6.5 in the case of non-damping, while it is 2 in the case of damping. In FIG. 15, the number of occurrences of 6.0 to 13.0 m/s ² is 6.5 without damping, and 4.5 with the damping device. From this analysis result, it was considered that the addition of the damping device has the effect of suppressing the repetition of the large response of the tank wall surface and promoting the damping.

By installing the damping device according to the present invention in the water tank, the wall response could be reduced. Furthermore, by conducting a rainflow analysis, it was possible to suppress the number of repeated occurrences of large displacements and large accelerations, and clarify the damping effect.

The damping device of the present invention can be used in a wide range of sizes of liquid storage tanks, from small tanks, such as water receiving tanks, to large tanks, such as contaminated water storage tanks. .

1 Damping Device 2 First Fixing Part 3 Second Fixing Part 4 Hollow Elastic Member 5 Supporting Member 50 Rectangular Tube 51 Angle Member 52 Flat Plate 6 Connecting Member 60 Plate-like Member 61 Frame Member T Liquid Storage Tank P Panel (Inner Wall)
S1 First side S2 Second side J Joined portion C Corner portion L Storage liquid R Reinforcing member

Claims (5)

In a damping device arranged in a liquid storage tank having a rectangular cross-sectional shape,
a first fixing part fixed to a first side surface of an inner wall of the liquid storage tank; a second fixing part fixed to a second side surface inside the liquid storage tank; and the first fixing part and the second fixing part. Equipped with a connecting member that connects the part,
the first side and the second side are adjacent to each other;
The first fixing portion and the second fixing portion each include a hollow elastic member and a support member that supports the hollow elastic member,
The damping device, wherein the connecting member connects the hollow elastic member of the first fixing portion and the hollow elastic member of the second fixing portion. 2. The damping device of claim 1, wherein the first side and the second side define four corners of the inner wall of the liquid storage tank. 3. The damping device according to claim 1, wherein the damping device is arranged vertically in a plurality of stages in the liquid storage tank. The liquid storage tank is a panel type tank formed by joining a plurality of panels, wherein the first fixing portion is fixed to the joint portion between the panels on the first side surface, and the second fixing portion is the second fixing portion. A damping device according to any one of claims 1 to 3, characterized in that it is fixed to the joint between the panels on two sides. The damping device according to any one of claims 1 to 4, wherein the hollow elastic member is made of a thermosetting elastomer or a thermoplastic elastomer.

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