JP2015117512A - Vibration control mechanism of columnar structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain divergent vibration in a columnar structure of a two-stack shell.SOLUTION: A vibration control mechanism of a two-stack shell steel tower support type chimney is provided with a first cylinder shell 3 and a second cylinder shell 4 in parallel in a steel tower, and the first cylinder shell 3 is fixed to the steel tower. The second cylinder shell 4 is connected to the steel tower via an oil damper capable of damping vibration. A plate 10 projecting outside from the second cylinder shell 4 is provided at an angle θ of 45° to a virtual line P of connecting the center of the first cylinder shell 3 and the second cylinder shell 4. A separation shear layer of wind of turning to the first cylinder shell 3 from the second cylinder shell 4 is kept away to the outside in the radial direction from the second cylinder shell 4 by the plate 10.

Description

  The present invention relates to a vibration control mechanism for a columnar structure in which vibration is suppressed in a chimney or the like in which two cylinders are supported by a steel tower.

2. Description of the Related Art Conventionally, an oil damper is used as a vibration control mechanism for enhancing the earthquake resistance and wind resistance of a plurality of chimneys supported by a steel tower. Since the vibration damping mechanism using the oil damper uses the relative displacement of a plurality of cylinders, each cylinder needs to move separately.
In the collective chimney described in Patent Document 1, a structure in which an anti-vibration plate material is provided on the outer surface of each cylinder instead of an oil damper has been proposed. In this collective chimney, a vibration isolating plate is provided on the outer surface of each cylinder on a line connecting the center axis of the three chimneys and the center axis of each cylinder.

  In addition, in a tower-supported chimney with two cylinders, the first cylinder is fixed to the steel tower and the second cylinder is separated from the steel tower to give relative displacement to the two cylinders. Some of them have a structure in which they are supported by an oil damper attached to the rocker so as to be swingable. In this case, the first cylinder is less likely to be shaken by an earthquake or wind, while the second cylinder is more likely to be shaken. Therefore, a relative displacement occurs between the two cylinders, which is caused by the oil damper. A damping addition effect is obtained.

JP 2012-158941 A

  However, the tower-supported chimney with the two cylinders mentioned above has special vibration characteristics, so even if it has an oil damper, it does not occur in a normal two-cylinder chimney, which is a fluid force caused by wind called galloping For this reason, divergent vibration, which is a phenomenon in which shaking does not stop, may occur. And if divergent vibration occurs in the two-cylinder chimney and the shaking becomes large, the chimney may be damaged.

  In view of such circumstances, an object of the present invention is to provide a vibration damping mechanism for a columnar structure that suppresses divergent vibration in a two-cylinder columnar structure.

A vibration damping mechanism for a columnar structure according to the present invention includes a first cylinder fixed to a support, a second cylinder disposed adjacent to the first cylinder, and a first cylinder installed on the support. A damping part capable of attenuating the vibration of the two cylinders, and a peeling shear layer of fluid projecting outward from the second cylinder and going from the second cylinder to the first cylinder, radially outward from the second cylinder And a vibration suppressing member that moves away from the head.
According to the present invention, with respect to the fluid from the second cylinder to the first cylinder, the vibration of the second cylinder is attenuated by the damping unit, and the fluid from the upstream side to the second cylinder is second When the cylinder is wound around, the peeling shear layer of the fluid is guided in a direction away from the second cylinder by the vibration suppressing member, so that the negative pressure in the vicinity of the second cylinder is reduced, and the vibration of the second cylinder is further reduced. Can be suppressed.

Further, the vibration suppressing member may be a plate.
Since the peeling shear layer of the fluid is guided in the direction away from the second cylinder by the plate, the negative pressure near the second cylinder is reduced, and the vibration of the second cylinder can be further suppressed.

Moreover, it is preferable that the vibration suppressing member has a tip portion set at an angle of 45 ° or more with respect to an imaginary line connecting the center of the second cylinder and the first cylinder.
If the attachment angle of the tip of the vibration suppressing member provided on the second cylinder is 45 ° or more , divergent vibration can be suppressed.

Moreover, it is preferable that the vibration suppression member protrudes 15% or more of the outer diameter d of the second cylinder.
If the vibration suppressing member protrudes outside by 15% or more of the outer diameter d of the second tube body, divergent vibration can be suppressed.

Further, the ratio S / d between the gap S between the first cylinder and the second cylinder and the outer diameter d of the second cylinder may be 3 or less.
When the ratio S / d of the gap S is 3 or less, the influence of installing the first cylinder and the second cylinder in parallel is confirmed, and an interference effect of the fluid flow occurs.
The vibration damping unit may be an oil damper.
The second cylinder may be connected to the support via an oil damper capable of damping vibration.

  According to the vibration damping mechanism of the columnar structure according to the present invention, in addition to the vibration damping portion that suppresses vibration in the second cylinder, the vibration suppressing member that moves the peeling shear layer of fluid away from the second cylinder radially outward. By providing, the vibration of the second cylinder can be suppressed and divergent vibration called galloping can be reduced.

It is the schematic which shows the two-cylinder steel tower support type chimney by embodiment of this invention. In FIG. 1, it is a horizontal sectional view which shows the attachment structure to the steel tower and oil damper of a 1st cylinder body and a 2nd cylinder body. In FIG. 2, it is explanatory drawing which shows the structure of the 2 cylinder body which attached the plate to the 2nd cylinder body. It is a figure which shows the relationship between the gap ratio of a 1st cylinder and a 2nd cylinder, and a Strouhal number. It is a schematic diagram which shows the relationship between arrangement | positioning of a 1st and 2nd cylinder, and the flow of a wind, (a) is based on embodiment, (b) is based on a prior art. FIG. 4 is a diagram illustrating an embodiment of the present invention and a relationship between a mounting angle of a plate to a second cylinder and a divergent vibration generation wind speed ratio. FIG. 4 is a diagram illustrating an embodiment of the present invention, and is a diagram illustrating a relationship between a plate protrusion length of a second cylinder and a divergent vibration generation wind speed ratio. It is a figure which shows the relationship between the amplitude and wind speed in the top part of a 2nd cylinder, (a) is based on embodiment, (b) is based on the prior art which does not provide a plate. It shows the modification of the plate provided in the 2nd cylinder, (a) is a bending type plate, (b) is a triangular plate, (c) is a figure which shows the plate supported by the support rod. is there.

Hereinafter, a two-cylinder steel tower supported chimney according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a two-cylinder tower-supported chimney 1 according to an embodiment, and a first cylinder 3 and a second cylinder 4 of a chimney stand on a base 2 and are installed upright in parallel. Has been. The periphery of the first cylinder 3 and the second cylinder 4 is surrounded by a steel tower 5. In addition, the top portions 3a and 4a of the first tube body 3 and the second tube body 4 projecting from the upper end of the steel tower 5 are reduced in diameter from, for example, a refracting portion to reach the upper end portion.

  In the horizontal cross-sectional view of the two-cylinder tower-supported chimney 1 shown in FIG. A two-cylinder body 4 is provided. The first tube body 3 is connected and rigidly connected via support portions 7 provided on the beam portions 5aa on the four sides facing each other of the frame portion 5a. The second cylinder body 4 is connected via oil dampers 8 provided on the beam parts 5bb on the four sides facing each other of the frame part 5b. The second cylinder body 4 can swing in two orthogonal directions, and each oil The vibration is attenuated by the damper 8. In the frame portions 5a and 5b, the central beam portions 5aa and 5bb have a common beam member.

  In FIG. 3, the first tube body 3 and the second tube body 4 have a predetermined gap S, the diameter of the second tube body 4 is d, and the gap ratio S / d is 3 or less, When S / d is 3 or less, the influence of the wind of the structure which arranged the 1st and 2nd cylinder bodies 3 and 4 in parallel has been confirmed. That is, in FIG. 4, when the gap ratio S / d is taken on the horizontal axis and the Strouhal number (non-dimensional generation frequency of vortices) is taken on the vertical axis, when the gap ratio S / d is 3 or less, The effect of wind between both cylinders 3 and 4 has been confirmed (see Okashima “Flow around a Series of Two Cylinders at High Reynolds Number”, Transactions of the Japan Society of Mechanical Engineers 44-384, 1978).

  Moreover, as shown in FIG. 3, the two plates 10 for suppressing galloping are provided in the outer peripheral surface of the 2nd cylinder 4. As shown in FIG. The plate 10 has an appropriate shape, for example, a rectangular plate shape, and is attached in the vertical direction of the second barrel 4 with its upper end positioned at the bent portion of the top 4 a of the second barrel 4. In the plan view shown in FIG. 3, the plate 10 with respect to the outer peripheral surface of the second cylinder 4 is the second cylinder with respect to a virtual line P connecting the center points O <b> 1 and O <b> 2 of the first cylinder 3 and the second cylinder 4. 4 is installed on a straight line extending radially outward from the outer peripheral surface through the center point O2, and the mounting angle θ of the plate 10 with respect to the virtual line P is set to 45 °, for example. The two plates 10 are set at the same angle θ on both sides with respect to the virtual line P, but may not be the same angle.

  Next, in FIG. 5, the relationship between galloping and the plate 10 will be described with reference to a schematic diagram showing the flow of air with respect to the first tube body 3 and the second tube body 4 arranged at predetermined intervals. In the horizontal cross section of the conventional two-cylinder chimney without the plate 10 shown in FIG. 5B, the fixed first cylinder 3 and the vibrated second cylinder 4 have a predetermined distance S (S / d). ≦ 3) In the state where the wind flows from the upstream side of the second barrel 4, the second barrel 4 is directed to the second barrel 4 in the direction orthogonal to the virtual line P as vibration in the drawing (for example, downward in FIG. 5). ). In this state, the peeling shear layer of the wind in the motion direction (lower side in the figure) flows in a position close to the second cylinder 4, so that the negative pressure increases and further force is applied in the downward motion F direction. The vibration becomes divergent.

On the other hand, in FIG. 5A, since the plate 10 is provided on the second cylinder 4 at a predetermined angle θ, the peeling shear layer of the wind in the movement direction (lower side in the figure) is guided by the plate 10. Since it flows in the direction away from the second cylinder 4, the negative pressure is reduced by moving away from the second cylinder 4, the downward additional force is weakened, and the vibration is not divergent. Such a phenomenon occurs on both sides of the second barrel 4 depending on the direction of the motion F.
Note that this phenomenon does not occur when the first cylinder 3 is not disposed at a position adjacent to the second cylinder 4.

Next, in FIG. 3, for the plate 10 provided on the second tube body 4, the protruding length W of the plate 10 is 15% or more of the diameter d of the second tube body 4, and the mounting angle θ of the plate 10 is 45 °. The range is ˜90 °.
Further, assuming that the height of the second cylinder 4 is H (for example, H = 200 m), the plate 10 is disposed below the bent portion of the top 4a of the second cylinder 4 in the height direction of the plate 10. The length L is equal to or longer than (1/6) H and up to (1/3) H. Although the length of the plate 10 may be longer than (1/3) H, the cost increases. Further, the position of the plate 10 on the second cylinder 4 is set to a length of (1/5) H or more downward from the top 4a within the range from the upper end to the upper end of the frame 5 shown in FIG. It is preferable to install over. Or you may install below from the height position a little lower than the upper end of the frame part 5, as shown in FIG.

Here, FIG. 6 is a diagram showing the relationship between the mounting angle θ of the plate 10 and the divergent vibration generating wind speed ratio. The divergent vibration generating wind speed ratio is (the generated wind speed of divergent vibration with the plate 10 attached) / (the generated wind speed of divergent vibration with the plate 10 not attached). Therefore, in FIG. 6, when the mounting angle θ of the plate 10 is 45 ° or more, the divergent vibration generation wind speed ratio is 3 with respect to the divergent vibration generation wind speed ratio (= 1) without the plate 10 attached. 0 times or more.
In FIG. 7, if the ratio (W / d) of the protruding length W of the plate 10 to the outer diameter d of the second cylinder 4 is 15% or more, the diverging vibration generating wind speed ratio does not attach the plate 10. Compared with the second cylindrical body 4 in the state, it is 3.5 times or more. In FIGS. 6 and 7, an upward arrow with a white circle indicates that the generated wind speed ratio of divergent vibration is higher than the plotted value.

Next, the plate 10 is attached to the second cylinder 4 with an attachment angle θ = 55 °, the protruding length W / d = 0.20 of the plate 10, and the length L in the height direction of the plate 10 is 40 m (= 1 / 5H; the height H of the second cylinder 4 is set to 200 m), and the relationship between the amplitude of the top 4a of the second cylinder 4 and the wind speed was measured. The result is shown in FIG.
When the plate 10 was not provided on the second cylinder 4, as shown in FIG. 8 (b), the amplitude of the top 4 a suddenly increased at a wind speed of 25 m / s or more, and divergent vibration occurred. On the other hand, when the plate 10 is attached to the second cylinder 4 in the present embodiment, as shown in FIG. 8 (a), the top portion even when the oil damper 8 is not provided (indicated by a white circle line). The amplitude of 4a increased slowly, the wind speed was 75 m / s, the amplitude was about 150 cm, and no diverging vibration occurred. In addition, when the plate 10 and the oil damper 8 were added to the second cylinder 4 (indicated by the black circle line), the amplitude of the top 4a further increased gradually, and the amplitude did not reach 100 cm at a wind speed of 75 m / s. . In FIG. 8, h≈0.5% and h≈5.1% are vibration constants.

  Since the two-cylinder tower support chimney 1 according to this embodiment has the above-described configuration, the wind flowing from the second cylinder 4 toward the first cylinder 3 with respect to the two-cylinder tower support chimney 1. Is generated, the peeling shear layer of the wind flowing along the second cylinder 4 is along the plate 10 provided at a predetermined angle θ (for example, θ = 45 ° to 90 °) on both sides of the second cylinder 4. The second cylindrical body 4 is caused to flow outward in the radial direction. Therefore, the peeling shear layer of the wind flows in a direction away from the second cylinder 4 along the attachment angle θ of the plate 10 and also flows in a region separated from the first cylinder 3.

Then, the negative pressure generated in the vicinity of the second cylinder 4 by the wind peeling shear layer in the movement direction (lower side in FIG. 5) is reduced, and the force acting in the direction of the movement F perpendicular to the virtual line P is suppressed. Therefore, vibration in a direction orthogonal to the virtual line P can be suppressed. Moreover, since the oil damper 8 is provided on each of the four sides of the frame portion 5b surrounding the second cylinder body 4, vibrations of the second cylinder body 4 generated at a wind speed of 25 m / s can be further suppressed (FIG. 8). (See (a)).
Therefore, when the 1st cylinder 3 and the 2nd cylinder 4 are arranged with the clearance gap S and a wind blows in the 1st cylinder 3 direction from the 2nd cylinder 4 side, the peeling shear layer of a wind is made by the plate 10 They can be separated and the occurrence of divergent vibration due to galloping can be suppressed.

  As described above, according to the two-cylinder tower-supported chimney 1 according to this embodiment, the first cylinder 3 and the second cylinder 4 are installed in parallel with a gap of S / d of 3 or less, and an oil damper is provided. Since the plate 10 is attached to the second cylindrical body 4 in addition to 8, the negative peeling generated in the vicinity of the second cylindrical body 4 away from the second cylindrical body 4 is small, so that divergent vibration is generated. The vibration damping effect is high and galloping can be suppressed.

The present invention is not limited to the two-cylinder tower-supported chimney 1 according to the above-described embodiment, and can be appropriately changed or replaced without departing from the gist of the present invention. It is included in the present invention.
For example, the plate 10 provided on the second cylindrical body 4 described above is formed in a substantially rectangular plate shape, but is not limited to the shape described above, and an appropriate shape such as a triangular plate shape or an arc shape is adopted. Can do.

Further, the plate 10 does not necessarily have a flat plate shape, and may have a bent or curved shape as shown in FIG. Further, as shown in FIG. 9 (b), the plate 10 has a triangular shape in which two plates are stacked at the tip, and as shown in FIG. 9 (c), one plate 10 is supported by another support rod or the like. A shape supported by a member may be employed. In particular, in the present invention, the portion of the free end portion (tip portion) separated from the second tube body 4 of the plate 10 may be at least in the range of 45 ° to 90 ° as the mounting angle θ.
Moreover, the attachment position to the 2nd cylinder 4 of the upper end of the plate 10 may be attached to the bending part in the top part 4a of the 2nd cylinder 4, and may be attached to the upper end part of the top part 4a on it, The vicinity of the upper end is preferable. Further, in the embodiment described above, the top portions 3a and 4a of the first tube body 3 and the second tube body 4 are formed so as to taper from the refracting portion and reach the upper end portion. 3 and the top part 3a, 4a of the 2nd cylinder body 4 may be the shape which does not provide a refractive part, and can employ | adopt an appropriate shape.
In the present invention, the steel tower 5 is included in the support, the oil damper 8 is included in the vibration damping portion, and the plate 10 is included in the vibration suppressing member.

DESCRIPTION OF SYMBOLS 1 Two-cylinder steel tower support type chimney 3 1st cylinder 3a, 4a Top part 4 Second cylinder body 5 Steel towers 5a, 5b Frame part 7 Support part 8 Oil damper 10 Plate

Claims (6)

A first barrel fixed to the support;
A second cylinder disposed with a gap in the first cylinder;
A damping part installed on the support and capable of damping the vibration of the second cylinder;
A vibration suppressing member that protrudes outward from the second tube body and moves a peeling shear layer of fluid from the second tube body toward the first tube body radially outward from the second tube body. Damping mechanism for columnar structures.   The vibration suppression mechanism for a columnar structure according to claim 1, wherein the vibration suppressing member is a plate.   The columnar structure according to claim 1 or 2, wherein the vibration suppressing member has a tip portion set at an angle of 45 ° or more with respect to an imaginary line connecting the center of the second cylinder and the first cylinder. Damping mechanism.   4. The vibration damping mechanism for a columnar structure according to claim 1, wherein the vibration suppressing member protrudes by 15% or more of the outer diameter d of the second cylindrical body. 5.   The columnar structure according to any one of claims 1 to 4, wherein a ratio S / d between a gap S between the first barrel and the second barrel and an outer diameter d of the second barrel is 3 or less. Damping mechanism for things.   The columnar structure damping mechanism according to any one of claims 1 to 5, wherein the damping unit is an oil damper.