JPH083286B2 - Vibration control device for tower structures - Google Patents

Description

The present invention relates to a vibration damping device for suppressing vibration of a tower-shaped structure due to wind or an earthquake.

[Conventional technology]

In recent years, a vibration control device based on the principle of a dynamic vibration absorber has come to be considered as a technique for preventing vibration of tower-like structures such as high-rise buildings and suspension bridges and towers of cable-stayed bridges against earthquakes and winds, and various proposals have been made. Has been done.

In general, a dynamic vibration absorber has a natural frequency that tunes to the natural frequency of a structure and an appropriate damping mechanism to absorb the vibration energy of the structure and suppress the vibration. Various embodiments are conceivable.

As this form, a combination of a mass, a spring and a damper is usually used. However, in this case, there are the following problems.

 It is difficult to adjust the natural frequency.

Maintenance of springs and dampers against aging is required.

 The structure and mechanism become complicated.

 There is a restriction on the space to store the vibration control device.

Recently, as one means to solve these problems,
A dynamic vibration absorber utilizing free surface wave (sloshing) of a liquid in a tank storing the liquid as disclosed in JP-A-62-101764, JP-A-62-292943 or JP-A-63-172092. Is proposed. These have a mechanism in which the natural frequency of sloshing is tuned to the natural frequency of the structure, and an obstacle such as a porous member against the motion of the liquid is provided in the liquid to attenuate the vibration. However, these have the following problems.

The behavior of sloshing becomes very complicated for a large amplitude vibration, and it becomes difficult to calculate the damping effect by the natural frequency and damping.

To obtain this accurately, refer to the literature (Toshiyuki Noji et al.
5) As shown in Architectural Institute Academic Lecture Summary, 1987, 1988), etc., it is necessary to use experimental means, and much labor is required.

The attenuation due to the porous member or the like is not clear and its calculation is difficult.

The installation space of the structure is restricted by the size of the tank that stores the liquid.

[Problems to be Solved by the Invention]

The present invention has been made in view of the above facts, and it is an object of the present invention to provide a vibration damping device that can exhibit a required vibration function with high accuracy and has a high degree of freedom in the installation space of the structure.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention provides a tower-shaped structure with a liquid column tube having an arbitrary shape having liquid surfaces at the rising portions at both ends, and an attenuation factor is provided in the middle part of the liquid column tube. It is characterized by the provision of an orifice that can be set to an optimum value.

[Action]

Due to the vibration of the tower-shaped structure, the liquid in the liquid column tube reciprocates in the length direction of the tube, and the liquid surface vibrates vertically. The movement of the liquid at this time is appropriately damped by the orifice, and the vibration of the structure is suppressed. The movement of the liquid is one-dimensional, and the damping rate can be controlled freely.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram of a vibration damping device for a tower-like structure. The vibration damping device A is composed of a liquid column tube 1, a liquid 2 and an orifice 3 which are provided at a location where vibration displacement of a tower-like structure (not shown) (hereinafter referred to as "structure") is large. Liquid 2
Is injected so that the liquid surface 2a comes to the rising portions of both ends of the liquid column tube 1. The cross-sectional shape of the liquid column tube 1 may be circular,
It may be a rectangle such as a square or a rectangle, or any other shape. or,
The length direction of the liquid column tube 1 may also draw an arbitrary curve.

When the structure shakes in the direction of arrow S, the free surface 2a of the liquid
Vibrates up and down in the direction of B. Although the liquid 2 itself has a damping capacity, the vertical movement of the liquid is mainly damped by the orifice 3.

The vibration energy of the structure is absorbed by the reciprocating motion of the liquid 2 in the liquid column tube 1, and the structure is damped. And
By setting the damping rate of the orifice 3 appropriately,
It helps to absorb this vibration energy efficiently. The orifices 3 may be provided at a plurality of places.

The vibration control device with such a configuration is installed in the TLCD (Tuned Liquid Col
umn Damper).

In the vibration equation of the liquid 2 in the liquid column tube of this vibration control device, when the displacement of the free surface 2a is B with respect to the displacement S of the structure, It is represented by. In the formula, ρ is the density of the liquid, g is the gravitational acceleration, A is the cross-sectional area of the liquid column tube 1, L is the length between the liquid surfaces 2a at both ends along the liquid column tube, and C is the liquid surface at both ends. Horizontal distance between 2a, K
Is a coefficient (pressure loss coefficient) determined by the throttle ratio of the orifice 3. Further, the marks (•) attached to B and S indicate time differentiation.

In this equation, the term on the right side can be a reaction force that vibrates the liquid 2 and at the same time suppresses the vibration of the tower structure. The first term and the third term on the left side of this vibration equation represent the mass effect and the spring effect, respectively. From these two terms, the natural period T of the liquid column vibration is Is obtained as.

Next, the second term on the left side is a term representing the damping property of the vibration of the liquid 2 by the orifice 3 provided in the liquid column tube 1. This damping property plays an important role in damping the vibration of the structure. That is, in order for the liquid column to vibrate and bring about a sufficient damping effect on the structure, this attenuation amount must be quantified to an optimum value. This damping property could not be easily quantified with the conventional structure using a porous member or the like, but since the pressure loss coefficient K is given as a known constant according to the orifice, this quantification is easy and reliable. Can be realized in. The pressure loss due to the orifice is measured by the Japanese Industrial Standard "JIS Z8762 Flow rate measurement method using a throttle mechanism".
As can be seen from Fig. 3, the quantification is easy, and the damping property when used as the damping mechanism of the vibration damping device can be easily evaluated. According to the present invention, this orifice is arranged in the liquid column tube so that the damping effect can be easily calculated and the TLCD can be designed easily and reliably.

FIG. 2 is a calculation example of a response curve showing that the vibration of the tower-shaped structure can be suppressed by disposing the TLCD. In the figure, the vertical axis represents the response magnification of the tower-shaped structure, and the horizontal axis represents the input frequency ratio, that is, the value obtained by (frequency of external force / natural frequency of tower-shaped structure).

In this way, the design of the TLCD as a vibration damping device can be achieved by being able to quantify the vibration equation easily and reliably.
The chart becomes simpler as follows.

 The simple design method will be described below.

First, the natural period T of the liquid column vibration is obtained as described above. On the other hand, the natural frequency of the structure is obtained from data at the design stage of the structure. From these, the length L is determined so that the ratio of the natural frequency of the structure and the natural frequency of the TLCD, that is, the liquid column tube, that is, the tuning ratio becomes close to 1.

FIG. 3 is a diagram showing the relationship between the two values, with the vertical axis representing the response value R _D indicating the displacement of the liquid column due to vibration and the horizontal axis representing the damping ratio h _D of the vibration damping device. These change as shown in each curve according to the change of the aperture ratio α of the orifice.
α ₁ , α ₂ , and α ₃ are the aperture ratios of the orifice, and α ₁ is small (large opening) and α ₃ is large (small opening). R _D and h _D are almost proportional to each other, and the straight line inclines in the direction in which the damping rate increases (the direction parallel to the horizontal axis) as the drawing rate α increases.

Fig. 4 (a) shows the response value R _S of the structure and the damping ratio of the vibration damping device.
is a diagram showing the relationship between h _D. Where μ = effective mass of the vibration damping device / equivalent mass of the structure, and μ ₁ is smaller and μ ₃ is larger. The response value increases as the damping rate h _D increases.
Although R _S decreases, it increases again when the attenuation rate h _D exceeds a certain level. It is possible to draw a dotted line parallel to the horizontal axis with the allowable limit of the response value of the structure as R _SL , and have an intersection point μ
The effective mass of the vibration damping device, that is, the size of the device is determined from the value of. Now, determine μ = μ ₂ and let the values of the attenuation rate h _D at the intersection with the μ ₂ curve be h _DA and h _DB . If the damping factor h _D is within this range, the response value of the structure can be within the limit R _SL . In addition, the intermediate h _Dopt is the optimum damping rate.

In Fig. 4 (b), the response value R _D of the vibration damping device due to vibration is plotted on the vertical axis and the damping ratio h _D of the vibration damping device is plotted on the horizontal axis, and the relationship between the two changes by changing the value of μ. It is a diagram showing how to do. The response value R _D decreases as the damping rate h _D increases. Also, the response value R _D rapidly increases as the damping rate h _D decreases. Here, the allowable response value R _DL of the liquid column is
It is a value determined by the range in which the liquid level 2a can move, depending on the place where the vibration damping device is installed. R _DO is the response value of the liquid column that _provides the optimum damping rate h _Dopt for μ ₂ , and a value smaller than the allowable response value R _{DL of the} liquid column is selected.

Figure 4 (c) are placed vertically response value R _D of the control device by vibration, taking the attenuation factor h _D of the damping device on the horizontal axis, due to a change in the drawing rate α of the orifice in the case of mu ₂ FIG. 7 is a diagram showing a change in attenuation rate h _D. The vertical axis is the response value R _DO of the liquid column determined by the above procedure, and the intersection with the optimum damping rate h _Dopt obtained in the explanation of FIG. 4 (a) is obtained. From the figure, this intersection can be found on the straight line of α ₂ .

From the above, the optimum damping ratio h _{Dopt and} other characteristic values of the vibration damping device are determined.

Each of the diagrams in FIGS. 3 and 4 is obtained by calculation regarding the liquid column tube and the orifice, and can be clearly quantified. In the conventional damping device by sloshing, it was difficult to quantify such damping rate due to the complex sloshing motion and damping by the porous member, etc., but an orifice is used for the liquid column tube. This facilitates quantification, improves the performance of the vibration damping device, and facilitates manufacturing.

FIG. 5 is a diagram showing the entire configuration of one embodiment of the present invention in the case of the primary vibration mode, in which the vibration damping device A is usually provided near the top of the tower-shaped structure 4 where the most effective effect can be exhibited. .
By the way, in the case of the secondary vibration mode, the maximum amplitude position may be in the middle part, so that it is provided in the vicinity thereof. In the case of a suspension bridge tower, the lower end is fixed to the base and the upper end is fixed to the wire.

FIG. 6 is a diagram for explaining the piping path of the liquid column tube 1.
If there is another obstacle 5 at the installation location of the tower-shaped structure 4,
The conventional vibration control device could not be installed. That is, a dedicated space for installation was required. However, with the vibration damping device of the present invention, the shape in the middle is arbitrary as long as the length of the liquid column tube 1 can be secured, and even if it detours, the natural frequency is not affected. Therefore, no special space for installing the vibration damping device is required. Further, since the liquid 2 normally uses water, it can be used for multiple functions such as for use as fire extinguishing water and equipment water.

FIG. 7 shows an example of installation in a spherical tower-shaped structure such as an elevated tank. A damping device A composed of TLCD is provided along the outer shape from the bottom to the top of the tank 6. in this case,
If two vibration damping devices A are combined at right angles and provided, all vibrations in the direction of the installation surface of the tank can be dealt with.

FIG. 8 shows an embodiment in which a large number of vibration damping devices A are attached to a spherical tank 6. When the cycle of the natural vibration of the entire structure is short, it is as in this embodiment, not in FIG.

FIG. 9 is an example in which the vibration damping device A made of the TLCD of the present invention is installed in a structure under construction. Since the tower-shaped structure 4 receives vibrations due to wind and earthquake not only after completion but also during its construction, it is desirable to have a vibration control device during construction. Therefore, the vibration damping devices A and A are provided at locations where vibration is likely to occur. 7 is a crane for constructing a tower structure.

FIG. 10 shows an embodiment in which the crane 8 under construction of the tower-shaped structure 4 is provided with the vibration damping device of the present invention. In the case of the vibration damping device of FIG. 9, it is necessary to relocate the vibration damping device as the building is extended upward. However, the crane 8 is used as a creeper crane or a similar type crane to construct the tower-like structure 4
If the tower structure 4 is provided on a crane that rises as it is extended upwards, the tower-shaped structure 4 is always the same as having a vibration damping device at the top even during its construction. Therefore, there is no need to relocate.

FIG. 11 is an example in which the vibration damping device of the present invention is used for the observatory as the tower-shaped structure 4. The vibration damping device A of the present invention is installed using the window frame or the like of the observatory 4. The observatory is surrounded by many vibration control devices as shown in the figure because of the cycle of vibration, space restrictions, and design. From this arrangement, all horizontal vibrations of the observatory are dampened.

FIG. 12 is a diagram showing an example of using a variable flow rate throttle valve having an orifice effect in which the throttle ratio can be adjusted in place of the orifice in order to make the opening area of the orifice variable. The variable flow throttle valve 11 is constructed by mounting fixed members 10 and 10 on both right and left sides in the liquid column tube 1 having a rectangular cross section, and providing movable members 9 and 9 between them. The movable members 9 and 9 are the liquid column tubes 1.
Although it is provided so as to penetrate through the pipeline wall, it has a known watertight structure with the pipeline wall. Then, one or both of the movable members 9 and 9 are provided with a driving means (not shown),
It is possible to move back and forth from the outside of the liquid column tube 1 into the liquid column tube 1 by an operation handle or the like. Therefore, the size of the movable hole 9a can be freely changed from the outside of the liquid column tube 1, and the throttling ratio of the opening that achieves the orifice effect can be adjusted.

FIG. 13 shows a variable flow throttle valve 11 in which the fixed member 10 in FIG. 12 is omitted and the movable member 9 is inserted only from one side of the liquid column tube 1.

FIG. 14 shows an example of a variable flow rate throttle valve 11 in which a movable member 9 having a size capable of closing the cross section of the liquid column tube 1 is rotatably provided by a shaft 9b as indicated by an arrow mark.

FIG. 15 shows an example in which the movable member 9 formed in an arc shape on the outer side is provided so as to face each other, and the liquid column tube 1 is formed with a bulging portion 1c for accommodating the arc shaped movable member. The movable members 9 facing each other are connected to the outside of the liquid column tube and are rotatably supported by a central shaft (not shown).
Is composed.

If such a variable flow restrictor 11 is used, the damping rate h _D of the vibration damping device can be easily changed, and further, the amount of liquid injected into the liquid column tube 1 can be adjusted to adjust the liquid level 2a at both ends. By changing the length L along the liquid column tube between the two, it is possible to easily follow changes in usage conditions, such as changes in the natural frequency of the structure, even when used in a structure under construction. Like

FIG. 16 shows an embodiment in which the vibration damping device A of the present invention is combined at a right angle. When suppressing the vibration of the tower-shaped structure, it is necessary to absorb the vibration not only in one direction but also in two or more directions, and two types of liquid column tubes may be arranged at right angles to each other. In that case, first, an arrangement as shown in FIG. 16 (a) can be considered. The distance between the rising portions on both sides of the two liquid column tubes 1 and 1 '(hereinafter referred to as "rising width") is B, respectively.
If B'and the width between the liquid columns 1,1 'is W, W', a space of B'x (B + W ') is required for installation, and the amount of liquid 2 is required to include both. become. If the structure is large, not only the length but also the width will reach several meters, and the installation space and the liquid amount will be a heavy burden.

On the other hand, the embodiment of FIG.
1, 1 ′ are crossed at the horizontal part, and the crossing part 1 a has a common duct. The orifices 3 are provided in the liquid column tubes 1, 1'as many as necessary. With such a configuration, it is possible to install in a space of B × B ′ only, and it is possible to reduce the liquid amount in the intersecting portion 1a. The crossing portion 1a is not always a liquid column tube.
It does not have to be in the center of 1,1 ', but may be provided at the end of the liquid column tube.

FIG. 17 shows an embodiment in which the rising portions at both ends of the liquid column tube are connected to form a corridor type liquid column tube 1. 12 in the figure
Is a lid for injecting the liquid 2 and an inert gas described later. The liquid column tube 1 as in the embodiment of FIG. 1 described above.
If both rising edges are open, the liquid will evaporate and the damping effect will be reduced over a long period of use. Also,
The liquid overflows when hit by a large amplitude that exceeds expectations.
Furthermore, rust and corrosion are likely to occur on the inner wall of the liquid column tube 1 near the liquid surface 2a.

Therefore, by using a corridor type liquid column tube 1 having both ends connected as shown in FIG. 17, it is possible to prevent the evaporation of the liquid 2 and the overflow at the time of a large amplitude. In addition, if an inert gas is filled, the liquid level 2a
It can also prevent rust on the inner wall in the vicinity.

The vibration characteristics of the tower structure change according to the construction stage. On the other hand, if the liquid amount of the vibration damping device A is changed as described above, it is possible to cope with a certain amount of change. But,
In many cases, it is not possible to follow the change of the liquid amount alone. In such a case, it is necessary to replace the liquid column tube 1 with one having a different length, the work for replacement is difficult, and the economic burden is great. Also grows.

Therefore, in the embodiment of FIG. 18, the length of the bottom horizontal portion of the liquid column tube 1 filled with the liquid can be changed. As shown in the figure, a sliding portion 1b is formed in the horizontal portion of the liquid column tube 1, a watertight packing 13 is provided to form a watertight structure, and the rising width B of the liquid column tube 1 is changed to set the liquid surface 2a at both ends. The length L along the liquid column tube in between is changeable.

With such a configuration, it is possible to change the liquid volume and length according to the construction stage to obtain optimum vibration characteristics, and
Even during installation of a tower structure, the vibration characteristics can be easily changed while maintaining the vibration damping function.

Water is usually used as the liquid used in the vibration damping device of the present invention. However, if water freezes in a cold region, the vibration damping function cannot be exerted. Therefore, it is necessary to continuously supply heat from a heat source to prevent freezing,
Equipment maintenance costs are also high.

Therefore, in the present invention, an antifreeze liquid such as ethylene glycol is mixed as necessary to prevent freezing.

〔The invention's effect〕

As described above, the vibration damping device of the present invention has the following effects.

From the vibration equation of the liquid, which shows the relationship between the vibration of the tower structure and the orifice throttling ratio, the throttling ratio of the orifice that has the optimum vibration damping effect can be calculated, which facilitates the quantification of each characteristic value and improves the performance. The vibration damping device can be obtained.

By adjusting the length of the liquid column tube and the amount of liquid,
Since it is possible to cope with a change in natural frequency associated with the progress of construction of the structure, it can be easily used in the construction stage of the structure.

If the lengths of the pipelines are the same, the intermediate shape is arbitrary, so there is flexibility in the installation space.

Maintenance is easy because there are no aged parts such as springs and dampers.

By using a variable flow rate throttle valve having an orifice effect and capable of finely adjusting the opening area, it is possible to easily cope with the case where the usage conditions change at the construction stage of the structure.

By sharing and crossing the conduit of the liquid column tube,
It is possible to obtain a device that can reduce the installation space and the amount of liquid and can suppress the vibration in all directions.

By making the liquid column tube a corridor type, it is possible to prevent liquid evaporation and rust on the inner wall of the liquid column tube.

With antifreeze mixed, it can be used even in cold regions without fear of freezing, equipment such as heat source is not required, and maintenance is easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a vibration damping device of the present invention, FIG. 2 is a diagram showing an example of response magnification-input frequency ratio of a tower-like structure by the vibration damping device of the present invention, and FIG. Diagram of response value R _{D of} liquid column-damping factor h _D of damping device, Fig. 4 (a) shows response value R _S of structure-damping factor h _{D of} damping device
, (B) is the response value R _{D of the} vibration control device-damping rate h _D of the vibration control device, and (c) is the response value R _D of the vibration control device for μ ₂ -Vibration control device Of the damping ratio h _D of Fig. 5, Fig. 5 is a structural diagram of the vibration damping device of the present invention, Fig. 6 is a perspective view showing a bypass of the liquid column pipe, and Fig. 7 is a spherical view of the vibration damping device of the present invention. (A) is a front view, (b) is a top view, FIG. 8 is a front view of another usage example used for a spherical structure, and FIG. 9 is a vibration damping device of the present invention. Fig. 10 is a perspective view showing an example in which the above is used for a structure under construction, Fig. 10 is a configuration diagram of one embodiment in which the vibration damping device of the present invention is applied to a creeper crane, and Fig. 11 is a vibration damping device of the present invention. Fig. 12 is a front view showing an example of using the observation deck as an observation deck, Fig. 12 is a diagram showing one configuration example of a variable flow rate throttle valve, (a) is a front sectional view, (b) is a transverse sectional view, and Fig. 13 is variable. It is a figure showing another example of composition of a flow restrictor,
(A) is a front cross-sectional view, (b) is a cross-sectional view, FIGS. 14 and 15 are cross-sectional views showing still another configuration examples of the variable flow rate throttle valve, and FIG. Fig. 17 is a perspective view of an embodiment in which the devices are combined at right angles, (b) is a perspective view showing an embodiment of a vibration damping device in which liquid column pipes are crossed, and Fig. 17 is an example using a corridor-type liquid column pipe. FIG. 18 is a perspective view showing the structure of a vibration damping device in which the length of the liquid column tube is variable. 1 ... Liquid column tube, 1a ... Crossing part, 1b ... Sliding part, 2 ... Liquid, 2a ... Liquid level, 3 ... Orifice, 4 ... Tower structure, 11 ... Variable flow restrictor valve.

Claims (5)

[Claims] 1. A tower-shaped structure is provided with a liquid column tube having an arbitrary shape having liquid surfaces at the rising portions at both ends, and an attenuation factor can be set to an optimum value in the middle portion of the liquid column tube. A vibration damping device for a tower-like structure, which is provided with an orifice. 2. The vibration damping device for a tower-like structure according to claim 1, wherein the orifice is a variable flow throttle valve whose throttle ratio can be adjusted. 3. A tower-shaped structure is provided with two liquid column pipes having liquid surfaces at the rising portions at both ends in an intersecting state in which a pipe line is shared in a horizontal portion, and each of the two liquid column pipes is arranged. A vibration damping device for a tower-like structure, which is provided with an orifice capable of setting an optimum damping ratio in an intermediate portion. 4. The tower-like structure according to claim 1, 2 or 3, wherein the leading ends of the rising portions at both ends of the liquid column tube are connected and connected by a conduit to form a corridor type liquid column tube. Vibration control equipment for goods. 5. A sliding portion having a watertight structure is provided in the middle of the liquid column tube,
The length of the liquid column tube is variable, Claims 1, 2,
The vibration damping device for a tower-like structure according to 3 or 4.