JP3707567B2 - Seismic device for double shell flat bottom cylindrical tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an earthquake resistant device for a double-shell flat bottom cylindrical tank having an outer tub.
[0002]
[Prior art]
FIG. 4A is a configuration diagram of a conventional double-shell flat bottom cylindrical tank. The tank shown in this figure is a double-shell tank having a hollow cylindrical shape with an inner tank 1 and an outer tank 2. The inner tank 1 is made of metal and the outer tank 2 is made of prestressed concrete. Gas (for example, LNG) is stored. In order to prevent gasification due to heat absorption of the liquefied gas, the cold insulation material 3 is filled between the side plates of the inner tank 1 and the outer tank 2, and the bottom cold insulation material 4 is interposed between the bottom plates of the inner tank 1 and the outer tank 2. Is pinched. Further, in order to prevent air from entering the inner tank 1, an inert gas (for example, nitrogen gas) is filled between the double shells from the breathing tank 5.
[0003]
FIG. 4B is an enlarged view of part A. As shown in this figure, in order to hold the inner tub 1 and the outer tub 2 in place, the outer tub 2 is installed on a strong foundation (for example, a concrete pile), and the inner basin anchor 6 is used for the foundation concrete. And the lower end of the side plate of the inner tank 1 are connected to hold the inner tank 1.
[0004]
[Problems to be solved by the invention]
The inner tank 1 needs to thermally expand and contract between the storage temperature of the liquefied gas (for example, about −162 ° C.) and the normal temperature. For this reason, a cold insulating material (for example, pearlite grains) having almost no rigidity is used for the cold insulating material 3 so that the inner tub 1 can freely move in the radial direction. The inner tank anchor 6 also extends vertically so that the side plate can move in the radial direction, so that the inner tank 1 is prevented from falling.
[0005]
In the conventional double-shell flat-bottom cylindrical tank described above, the inner tank 1 that is self-supporting in the outer tank 2 alone bears the horizontal force and the falling moment acting on the inner tank 1 in the event of an earthquake, and the inner tank at the lower end of the side plate. A load is transmitted to the foundation via the anchor 6 and the bottom plate of the outer tub 2. For this reason, when the upper part of the inner tank 1 vibrates left and right due to an earthquake, the internal liquefied gas also vibrates, thereby causing a problem that a large dynamic pressure acts on the side plate and the internal stress becomes excessive. Further, the burden on the lower side plate of the inner tank 1 and the anchor strap (inner tank anchor 6) is excessive, and there is a problem that it is necessary to strengthen the lower end of the side plate and increase the number of inner tank anchors. Moreover, since the bottom face of the inner tank 1 is only left still on the bottom cooler, if the horizontal force becomes excessive, the inner tank may slide on the upper face of the bottom cooler.
[0006]
The present invention has been made to solve such problems. That is, the object of the present invention is to transmit a part of the seismic force acting on the inner tank to the outer tank without restricting the movement of the inner tank in the radial direction. An object of the present invention is to provide a seismic device for a double-shell flat bottom cylindrical tank that can reduce the burden on the tank anchor and reduce the vibration of the upper part of the inner tank during an earthquake. Another object of the present invention is to provide a seismic device for a double-shell flat bottom cylindrical tank that can attenuate the vibration of the upper part of the inner tank in the event of an earthquake.
[0007]
[Means for Solving the Problems]
According to the present invention, in a double-shell flat bottom cylindrical tank having a flat bottom hollow cylindrical inner tank and an outer tank, a plurality of pairs of elongated tensile members attached to the upper part of the inner tank and the outer tank, and the roof of the outer tank And a damping device that absorbs an axial tensile force at an intermediate portion of the tension member , and each pair of tension members is pivotable with one end of each pair close to the inner surface of the outer tub. A seismic resistance of a double-shell flat bottom cylindrical tank, which is mounted, extends horizontally in a direction opposite to the outer surface of the inner tank in opposite directions, and has the other end rotatably mounted on the outer surface of the inner tank. An apparatus is provided.
[0008]
According to the above configuration of the present invention, the elongated tensile member extends horizontally in a direction in contact with the outer surface of the inner tank, and both ends are rotatably attached to the inner tank and the outer tank. Even if the inner tub mounting part of each tension member moves in the radial direction due to heat shrinkage, the tensile member almost pivots around the outer tub mounting part and almost restrains the radial movement of the inner tank. do not do. On the other hand, if the inner tank is displaced in the horizontal direction during an earthquake, both the inner tank mounting portions of the pair of tensile members located on the opposite side of the moving direction are displaced in the horizontal direction together with the inner tank. The tension is applied to the outer tank, and this tension is transmitted to the outer tank attached in close proximity. Therefore, part of the seismic force acting on the inner tank can be transmitted to the outer tank via the pair of tensile members, thereby reducing the burden on the lower end of the inner tank and the inner tank anchor, and in the event of an earthquake. The vibration of the upper part of the inner tank can be reduced. In addition, since the tension | tensile_strength of both tension members acts in the circumferential direction of an inner tank, even if it is an inner tank with low out-of-plane direction (radial direction) rigidity, there is almost no possibility of buckling. Moreover, the vibration of the upper part of the inner tank at the time of an earthquake can be attenuated in a short time by providing the attenuation device.
[0009]
The outer tub is preferably made of concrete. By using the outer tank made of concrete with high rigidity, a part of the seismic force acting on the inner tank can be transmitted to and supported by the outer tank via a pair of tension members without any particular reinforcement.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each drawing, common parts are denoted by the same reference numerals.
1A and 1B are pressure distribution diagrams in a double-shell flat bottom cylindrical tank, where FIG. 1A is an acceleration type earthquake and FIG. 1B is a sloshing. As is clear from FIGS. 1A and 1B, the hydrostatic pressure and the hydraulic pressure due to the vertical movement are larger in the lower part of the tank, but the side plate dynamic pressure and the seating pressure due to the rise in the liquid level are It is quite big. Therefore, during an earthquake, a large horizontal force acts on the upper part of the tank, and when this horizontal force or overturning moment is transmitted to the foundation via the inner tank anchor at the lower end of the side plate and the bottom plate of the outer tank as in the past. It can be seen that the burden on the lower side plate of the inner tank and the inner tank anchor becomes excessive. When the upper part of the inner tank vibrates left and right due to an earthquake, the internal liquefied gas also vibrates and goes wild, which may cause a large dynamic pressure on the side plate and excessive internal stress. Moreover, since the bottom face of the inner tank is only left standing on the bottom cooler, if the horizontal force becomes excessive, the inner tank may slide on the upper face of the bottom cooler.
[0011]
FIG. 2 is an overall configuration diagram of a double-shell flat bottom cylindrical tank equipped with a seismic device according to the present invention, where (A) is a horizontal sectional view and (B) is a side sectional view. The double-shell flat bottom cylindrical tank 7 in this figure is a flat-bottomed double-shell tank in which the inner tank 1 and the outer tank 2 are hollow cylindrical, the inner tank 1 is made of metal, and the outer tank 2 is made of prestressed concrete. Yes. The inner tank 1 stores a low-temperature liquefied gas (for example, LNG). By using a highly rigid concrete for the outer tub 2 as in this embodiment, a part of the seismic force acting on the inner tub 1 is transmitted to the outer tub as described later without any particular reinforcement. Can do. In addition, this invention is not limited to this, For example, you may reinforce and use a metal outer tank.
[0012]
3A is an enlarged view of a portion B in FIG. 2A, and FIG. 3B is a partially enlarged view thereof. As shown in FIG. 3 (A), the seismic device 10 according to the present invention comprises a plurality of pairs of elongated tension members 12 and 13. Each pair of tension members 12 and 13 is installed in the upper part of inner tub 1 at intervals in the circumferential direction and also at intervals in the vertical direction.
Each pair of tension members 12 and 13 is rotatably attached to a lug 8a of the reinforcing ring 2a of the outer tub 2 in which both ends 12a and 13a are provided close to the inner surface of the outer tub 2. . Each pair of tension members 12 and 13 extends horizontally from the outer tub mounting portion (one end 12a and 13a) in a direction in contact with the outer surface of the inner tub 1 in opposite directions. Further, as shown in FIG. 3A, the other ends 12b and 13b of the tension members 12 and 13 are rotatably attached to lugs 8b of the reinforcing ring 1a provided on the outer surface of the inner tank 1, respectively.
[0013]
As schematically shown in FIG. 3B, the tension members 12 and 13 are elongated rods having male screw portions at both ends, a spherical washer with one side spherical, a nut with one side spherical, a nut for preventing loosening, etc. It can be attached between the lugs 8a and 8b without loosening and can be rotated at both ends. In addition, this invention is not limited to the tension member shown in FIG. 3, A long and slender plate-shaped member may be sufficient, and the attachment of both ends may also be attached rotatably with a pin.
[0014]
With the configuration described above, the elongated tensile members 12 and 13 extend horizontally in a direction in contact with the outer surface of the inner tank 1, and both ends 12 a, b, 13 a and b are rotatably attached to the inner tank 1 and the outer tank 2. Therefore, even if the inner tub 1 is thermally expanded and contracted, and the inner tub mounting portions (the other ends 12b and 13b) of the tensile members 12 and 13 are moved in the radial direction, the tensile members 12 and 13 are It is only slightly rotated around the mounting portion (one end 12a, 13a), and hardly moves the inner tank 1 in the radial direction. Similarly, it is not constrained to vertical displacement (movement) due to thermal contraction of the inner tank. On the other hand, when the inner tub 1 is displaced in the horizontal direction (rightward in FIG. 3) in the event of an earthquake, a tension acts on the tension member 13 at a position where the distance between both ends of the rod extends, and this tension is attached in the vicinity. Is transmitted to the outer tank 2. Therefore, a part of the seismic force acting on the inner tank 1 can be transmitted to the outer tank 2 through the pair of one tensile member 13, thereby reducing the burden on the lower side plate of the inner tank 1 and the inner tank anchor. In addition, the vibration of the upper part of the inner tank during an earthquake can be reduced. It is also possible to prevent the inner tank from sliding due to a large earthquake input.
[0015]
Furthermore, as schematically shown in FIG. 3 (B), an attenuation device 15 that absorbs the tensile force in the axial direction may be provided at an intermediate portion between the tension members 12 and 13. For the damping device 15, for example, an oil damper or a laminated material made of materials having different yield points can be used. When such a damping device 15 is used, the damping device 15 is suspended from the roof of the outer tub 2 by an appropriate hanger device, and the tension members 12 and 13 are not bent downward due to the weight of the damping device 15 (the level can be maintained). It is better to do so. By providing this damping device 15 in the middle part of the tension members 12 and 13, the vibration of the upper part of the inner tank at the time of an earthquake can be attenuated in a short time.
[0016]
In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.
[0017]
【The invention's effect】
As described above, the earthquake resistant device for the double-shell flat bottom cylindrical tank of the present invention transmits a part of the seismic force acting on the inner tank to the outer tank without restricting the radial movement due to the thermal contraction of the inner tank. Therefore, the load on the lower side plate of the inner tank and the inner tank anchor can be reduced, and the vibration of the upper part of the inner tank during an earthquake can be reduced and attenuated.
[Brief description of the drawings]
FIG. 1 is a pressure distribution diagram in a double-shell flat bottom cylindrical tank.
FIG. 2 is an overall configuration diagram of a double-shell flat bottom cylindrical tank.
FIG. 3 is an enlarged view of a portion B in FIG. 3 and a partial enlarged view thereof.
FIG. 4 is a configuration diagram of a conventional double-shell flat bottom cylindrical tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inner tank 1a Reinforcement ring 2 Outer tank 2a Reinforcement ring 3 Cold insulation material 4 Bottom cold insulation material 5 Breathing tank 6 Inner tank anchor 8a, 8b Lug 10 Seismic device 12, 13 Tensile member 12a, 13a One end 12b, 13b The other end 15 Attenuator

Claims (2)

In a double shell flat bottom cylindrical tank having a flat bottom hollow cylindrical inner tank and an outer tank,
A plurality of pairs of elongated tension members attached to the top of the inner and outer tubs ;
A damping device that is suspended from the roof of the outer tub and absorbs an axial tensile force at an intermediate portion of the tension member,
Each pair of tension members is rotatably attached with one end of each pair close to the inner surface of the outer tub, extends horizontally in a direction opposite to the outer surface of the inner tub in opposite directions, and the other end is an outer surface of the inner tub. An anti-seismic device for a double-shell flat-bottom cylindrical tank, characterized in that it is pivotably attached to the cylinder.   The said outer tank is a product made from concrete, The earthquake resistant apparatus of the double shell flat bottom cylindrical tank of Claim 1 characterized by the above-mentioned.

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