JPH09125738A - Anti-seismic device for cylindrical tank with double shell flat bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce upper part vibrations of an inner shell of a cylindrical tank having a flat bottom, which is composed of inner shell made of a metal material and an outer shell made of concrete, by coupling together the tops of the inner and outer shells using a plurality of thin and long tensile members in pairs, and thereby absorbing the vibration in the tangential direction of the inner shell. SOLUTION: A cylindrical tank having a flat bottom is composed of an inner shell 1 made from a low temp. metal plate and an outer shell 2 made of prestressed concrete, wherein a reinforcing ring la is furnished on the periphery of the inner shell 1 while a reinforcing ring 2a is fitted in the inside circumferential surface of the outer shell 2, and the two rings are coupled together by thin and long tensile members 12, 13. The tensile members 12, 13 should be in contact with the periphery of the inner shell 1, and a damping device 15 such as oil damper is installed on the way of laying of tensile members 12, 13 so that an anti-seismic device 10 is constructed. It may also be accepted that a plurality of such anti-seismic device 10 are installed at stages with a certain spacing up and down. Thereby the upper part vibrations of the inner shell 1 in the event of earthquake are reduced, and the burden on its anchors can be mitigated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earthquake-proof device for a double-shell flat-bottomed cylindrical tank having an outer tank.

[0002]

2. Description of the Related Art FIG. 4 (A) is a structural view of a conventional double-shell flat-bottomed cylindrical tank. The tank shown in this figure is a double-shell tank in which the inner tank 1 and the outer tank 2 are hollow cylindrical and have a flat bottom. The inner tank 1 is made of metal and the outer tank 2 is made of prestressed concrete, and liquefied into the inner tank 1. It is adapted to store gas (eg LNG). Further, in order to prevent gasification of the liquefied gas due to heat absorption, a cold insulating material 3 is filled between the side plates of the inner tank 1 and the outer tank 2, and a bottom cold insulating material 4 is placed between the bottom plates of the inner tank 1 and the outer tank 2. Is pinched. Further, in order to prevent air from being mixed in the inner tank 1, an inert gas (for example, nitrogen gas) is filled between the double shells from the breathing tank 5.

FIG. 4B is an enlarged view of part A. As shown in this figure, in order to hold the inner tank 1 and the outer tank 2 at predetermined positions, the outer tank 2 is installed on a strong foundation (for example, concrete pile), and the inner tank anchor 6 is used to form the foundation concrete. The inner tank 1 is held by connecting the lower end of the side plate of the inner tank 1 with the inner tank 1.

[0004]

The inner tank 1 is required to thermally expand and contract between the storage temperature (for example, about -162 ° C.) of liquefied gas and room temperature. Therefore, as the cold insulating material 3, a cold insulating material (for example, pearlite grains) having almost no rigidity is used so that the inner tank 1 can freely move in the radial direction. The inner tank anchor 6 also extends vertically so that the side plates can move in the radial direction, and prevents the inner tank 1 from falling.

In the above-mentioned conventional double-shell flat-bottomed cylindrical tank, the horizontal force and the overturning moment acting on the inner tank 1 in the event of an earthquake are independently borne by the inner tank 1 which is self-supporting in the outer tank 2, and the lower end of the side plate. The load is transmitted to the foundation through the inner tank anchor 6 and the bottom plate of the outer tank 2. For this reason, when the upper part of the inner tank 1 vibrates to the left and right due to an earthquake, the liquefied gas inside also vibrates, which causes a large dynamic pressure to act on the side plates, resulting in an excessive internal stress. In addition, there is a problem that the lower end of the side plate of the inner tank 1 and the anchor strap (inner tank anchor 6) become excessively heavy, and it is necessary to strengthen the lower end of the side plate and increase the number of inner tank anchors. Further, since the bottom surface of the inner tank 1 is merely left standing on the bottom cold insulating material, if the horizontal force becomes excessive, the inner tank may slide on the top surface of the bottom cold insulating material.

The present invention has been made to solve such a problem. That is, an object of the present invention is to transmit a part of the seismic force acting on the inner tank to the outer tank without restraining the radial movement of the inner tank. An object of the present invention is to provide an earthquake-proof device for a double-shell flat-bottomed cylindrical tank that can reduce the load on the tank anchor and reduce the vibration of the upper part of the inner tank in the event of an earthquake. Another object of the present invention is to provide an earthquake-proof device for a double-shell flat-bottomed cylindrical tank that can damp the vibration of the upper part of the inner tank in the event of an earthquake.

[0007]

According to the present invention, a double-shell flat-bottomed cylindrical tank having a flat-bottomed hollow cylindrical inner tank and an outer tank is provided with a plurality of pairs of elongated tension members, and each pair of tension members. Both ends are rotatably attached close to the inner surface of the outer tub, extend horizontally in opposite directions to contact the outer surface of the inner tub, and the other ends are rotatably attached to the outer surface of the inner tub respectively. A seismic device for a double-shell flat-bottomed cylindrical tank, characterized in that it is installed.

According to the above-mentioned structure of the present invention, since the elongated tension member extends horizontally in the direction of contacting the outer surface of the inner tank and both ends are rotatably attached to the inner tank and the outer tank, the inner tank is Even if the inner tank mounting part of each tension member moves in the radial direction due to thermal expansion / contraction, the tension member only moves slightly around the outer tank mounting part, and the inner tank moves in the radial direction. Hardly restrains. On the other hand, when the inner tank is displaced horizontally during an earthquake, both inner tank mounting parts of the pair of tension members located on the opposite side of the moving direction are horizontally displaced together with the inner tank. Is applied to the outer tub, which is closely mounted. Therefore, a part of the seismic force acting on the inner tank can be transmitted to the outer tank through the pair of tension members, thereby reducing the load on the lower end of the side plate of the inner tank and the anchor of the inner tank, and in the event of an earthquake. The vibration of the upper part of the inner tank can be reduced. Since the tensions of both tension members act in the circumferential direction of the inner tank, there is almost no risk of buckling even in an inner tank having low rigidity in the out-of-plane direction (radial direction).

According to a preferred embodiment of the present invention, it is preferable to provide a damping device (for example, an oil damper) for absorbing an axial pulling force at an intermediate portion of the pulling member.
By providing this damping device, the vibration of the upper part of the inner tank in the event of an earthquake can be damped in a short time. The outer tank is preferably made of concrete. By using the highly rigid concrete outer tank, a part of the seismic force acting on the inner tank can be transmitted to and supported by the outer tank through the pair of tension members without any particular reinforcement.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is a pressure distribution diagram in a double-shell flat-bottomed cylindrical tank, (A)
Is for acceleration type earthquake, and (B) is for sloshing. As is clear from FIGS. 1 (A) and 1 (B), the hydrostatic pressure and the hydraulic pressure due to vertical movement are greater toward the lower part of the tank, but the side plate dynamic hydraulic pressure and the sitting pressure due to the rise of the liquid level are also related to the upper part of the tank. Quite large. Therefore, in the event of an earthquake, a large horizontal force acts on the upper part of the tank, and when this horizontal force and the overturning moment are transmitted to the foundation through the inner tank anchor at the lower end of the side plate and the bottom plate of the outer tank, as in the conventional case. It can be seen that the load on the lower end of the inner tank side plate and the inner tank anchor becomes excessive. When the upper part of the inner tank vibrates left and right due to an earthquake, the liquefied gas inside also vibrates and violates, which may cause a large dynamic pressure to act on the side plates, resulting in excessive internal stress. In addition, since the bottom surface of the inner tank is only left standing on the bottom cool material, if the horizontal force becomes excessive, the inner tank may slide on the bottom cool material upper surface.

2A and 2B are overall structural views of a double-shell flat-bottomed cylindrical tank equipped with an earthquake-proof device according to the present invention. FIG. 2A is a horizontal sectional view and FIG. 2B is a side sectional view. In the double-shell flat-bottomed cylindrical tank 7 in this figure, the inner tank 1 and the outer tank 2 are hollow-cylindrical and flat-bottomed double-shell tanks.
The outer tank 2 is made of prestressed concrete. Further, a low temperature liquefied gas (eg, LNG) is stored in the inner tank 1. As in this embodiment, by using concrete having high rigidity for the outer tub 2, it is possible to transmit a part of the seismic force acting on the inner tub 1 to the outer tub as will be described later without any particular reinforcement. You can The present invention is not limited to this, and for example, a metal outer tank may be reinforced and used.

FIG. 3A is an enlarged view of portion B of FIG. 2A, and FIG. 3B is a partially enlarged view thereof. FIG. 3 (A)
As shown in FIG. 1, the seismic resistant device 10 according to the present invention comprises a plurality of pairs of elongated tension members 12, 13. Each pair of tension members 1
2, 13 are installed in the upper part of the inner tank 1 at intervals in the circumferential direction and at intervals in the vertical direction. Further, the pair of tension members 12 and 13 are rotatably attached to the lugs 8a of the reinforcing ring 2a of the outer tub 2 provided with both ends 12a and 13a thereof close to the inner surface of the outer tub 2. . In addition, the tension members 12 and 13 of each pair are attached to the outer tank mounting portion (one end 1
2a, 13a) extend horizontally in opposite directions to each other and in contact with the outer surface of the inner tank 1. Further, as shown in FIG. 3 (A), the other ends 12b, 13b of the tension members 12, 13 are rotatably attached to the lugs 8b of the reinforcing ring 1a provided on the outer surface of the inner tank 1, respectively.

As shown schematically in FIG. 3 (B), the tension members 12 and 13 are elongated rods having male threads at both ends, a spherical washer having one spherical surface, a nut having one spherical surface, and a loosening prevention member. It is composed of nuts and the like, and is attached between the lugs 8a and 8b without loosening and can be rotated at both ends. The present invention is not limited to the tension member shown in FIG. 3, but may be an elongated plate-shaped member, and both ends may be attached rotatably by pins.

With the above-mentioned structure, the elongated tension member 1 is provided.
2, 13 extend horizontally in the direction of contacting the outer surface of the inner tank 1,
Since both ends 12a, b, 13a, b are rotatably attached to the inner tub 1 and the outer tub 2, the inner tub 1 thermally expands and contracts, and the inner tub mounting portions of the tension members 12, 13 are attached. (Other end 12
b, 13b) even if it moves radially, the tension members 12,
The reference numeral 13 only slightly rotates about the outer tank mounting portion (one end 12a, 13a), and does not substantially restrain the radial movement of the inner tank 1. Similarly, it does not restrain vertical displacement (movement) due to thermal contraction of the inner tank. On the other hand, when the inner tank 1 is displaced in the horizontal direction (rightward in FIG. 3) during an earthquake, tension acts on the tension member 13 at the position where the distance between both ends of the rod extends, and this tension is attached closely. Outer tank 2
Is transmitted to Therefore, a part of the seismic force acting on the inner tub 1 can be transmitted to the outer tub 2 via the pair of tension members 13, thereby reducing the load on the lower end of the side plate of the inner tub 1 and the inner tub anchor. In addition, the vibration of the upper part of the inner tank in the event of an earthquake can be reduced. It is also possible to prevent the inner tank from sliding due to a large earthquake input.

Further, as schematically shown in FIG.
A damping device 15 that absorbs a 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. Such a damping device 15
When using, the damping device 15 is suspended from the roof of the outer tub 2 by a suitable hanger device so that the weight of the damping device 15 does not cause the tension members 12 and 13 to bend downward (the horizontal can be maintained). Is good. By providing the damping device 15 at the intermediate portion between the tension members 12 and 13, it is possible to damp the vibration of the upper part of the inner tank in the event of an earthquake in a short time.

The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0017]

As described above, the earthquake-proof device for a double-shell flat-bottomed cylindrical tank of the present invention does not restrict the radial movement of the inner tank due to thermal contraction, and a part of the seismic force that acts on the inner tank. Can be transmitted to the outer tank, which reduces the load on the lower end of the side plate of the inner tank and the inner tank anchor, and can reduce and damp the vibration of the upper part of the inner tank during an earthquake. Have an effect.

[Brief description of the drawings]

FIG. 1 is a pressure distribution diagram in a double-shell flat-bottomed cylindrical tank.

FIG. 2 is an overall configuration diagram of a double-shell flat-bottomed cylindrical tank.

FIG. 3 is an enlarged view of part B of 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]

 1 Inner tank 1a Reinforcing ring 2 Outer tank 2a Reinforcing ring 3 Cooling material 4 Bottom cooling 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 Damping device

Claims (3)

[Claims] 1. A double-shell flat-bottomed cylindrical tank having a flat-bottomed hollow cylindrical inner tank and an outer tank, wherein a plurality of pairs of elongated tension members are provided, and one end of each pair of tension members is the inner surface of the outer tank. Is rotatably attached in close proximity to each other, extends horizontally in a direction contacting the outer surface of the inner tank in opposite directions, and the other ends are rotatably attached to the outer surface of the inner tank, respectively. Seismic device for double-shell flat-bottom cylindrical tank. 2. The earthquake-proof device for a double-shell flat-bottomed cylindrical tank according to claim 1, further comprising a damping device that absorbs a tensile force in an axial direction at an intermediate portion of the tension member. 3. The earthquake-proof device for a double-shell flat-bottom cylindrical tank according to claim 1, wherein the outer tank is made of concrete.