JPS59103048A - Pendulum type dynamic vibration absorber - Google Patents

Abstract

PURPOSE:To reduce the frictional force acting on weights to simplify the mechanism by mutually opposing two or more plates having weights at the lower parts thereof, and mounting these plates on a support frame by wire hinges, in the titled dynamic vibration absorber suppressing a horizontal vibration of a tower- shaped structure. CONSTITUTION:Two or more weight suspending plates 2 and 2' having an elongated shape in the upward and downward direction are suspended down from the support frame 1 swingable on the perpendicular face in the vibrating direction to be controlled by means of wire hinges 3 and 3'. Weights 4 and 4' are mounted on the lower parts of the weight suspending plates 2 and 2'. A damper 9 of a viscous elastic member or a viscous member is mounted on the upper parts of the plates 2 and 2'. This damper 9 is fitted by a bolt 12 between damper fitting plates 11 and 11' axially supported in a rotatable manner by pins 10 and 10'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pendulum hole dynamic vibration absorber for suppressing horizontal vibration caused by wind or the like in a tower-like structure.

Tower-shaped structures, such as the main tower of a long bridge that becomes independent during construction, generate Karman vibration due to relatively low wind speeds, which is harmful to the tower construction work and the strength of the tower structure. (
The main tower of a long bridge will be explained below as an example. ] In order to suppress the above-mentioned vibrations, the main method used in the past was to extend a cable from the tower and attach a damper to the end of the cable. This method includes, for example, a sliding block method that adds damping properties to the vibration system using Coulomb friction between the No. 11 block and the slide, and (2) a hydraulic damper that adds damping properties to the vibration system using oil vortex formation resistance. There are hydraulic damping methods, etc.

However, these methods lack quantitative reliability of the damping effect in the case of (t+) and have problems with block operability;
In the case of 2), the problem of +17 will be resolved, but there is a major point of concern in that even though construction is underway, stringing a cable will pose a considerable hindrance to securing the sea area and the location for installing the attenuator. Therefore, there is a need for a vibration damping method that does not require cables.

Possible methods that do not involve stringing cables include aerodynamic measures and vibration damping using dynamic vibration absorbers. lal for aerodynamic measures
Method using partition plates and nets (Reference: Bridges and Foundations 1q74
-6. Wind resistance stability and vibration damping method of suspension bridge main tower during construction J
), lbl cowling system (Reference: Mitsubishi Heavy Industries Technical Report vO
e-14, No. 3, 1977, 5, ``Wind resistance stability when constructing a main tower of a long suspension bridge,'' etc., but all of them are beyond the realm of experimentation and there are no examples of actual use. Additionally, there are various problems regarding the installation of these devices.

Next, the vibration damping method using a dynamic vibration absorber is also a method that does not require ropes.
Since the present invention is also included in this system, the basic principle thereof will be explained first.

(The dynamic vibration absorber is 'IBM D [Tuned Mas
It is sometimes called s Damp -er j. Once the size, mass, rigidity, etc. of the structure and the mode shape of the target vibration are known, the following six characteristic values are determined, which are sufficient to determine the nature of the vibration. This can be shown as a model as shown in Figure 1. In the figure, MT is the equivalent mass of the structure (tS/rn), KT is the equivalent spring of the structure ('/m), and CT is the equivalent damping of the structure (''/m
) is shown. iMd on this structure.

FIG. 2 shows a model of the state in which a dynamic vibration absorber having vibration characteristic values of spring Kd and damping Cd is attached. However, if the change in the resonance curve of a structure to which this dynamic vibration absorber is installed (when the damping coefficient Cd of the dynamic vibration absorber is taken as a parameter) is similarly shown in a model, it becomes as shown in FIG. In Figure 6, the vertical axis is the response magnification, and the horizontal axis is the external force frequency ω0/natural frequency (IJT).
The curve d=O is the state where there is no damping of the dynamic absorber, Cd-■
The curve is the mass M of the dynamic vibration absorber (l is the mass MT of the structure
In both cases, the response amplitude is large. c.
The curve d=ca-i shows the state when a dynamic vibration absorber is installed, and the response amplitude of the structure decreases, ' cd "" ca
The *Qp L curve represents the situation when a dynamic damper with an optimal value of the damping coefficient is installed, and the response amplitude of the structure is considerably reduced. That is, appropriate values of Md, Kd,
If a dynamic vibration reducer with Cd is attached to a structure, the amplitude of vibration due to external force can be suppressed by a considerable amount.

MT t KT v' (: 'T of the structure, there is the following relationship between Md, Kd, Cd of the dynamic vibration absorber and damping efficiency (expressed as a logarithmic damping coefficient).

Mass ratio β = and...
・・・・・・・・・・・・・・・・・・・・・・・・(1)
MT Optimal natural frequency ωdeopt of dynamic vibration absorber Optimal damping coefficient cd-op [as above (Mct, Kd
, Cd are set, the logarithmic damping coefficient δT of the main structure is as follows.

When trying to create a dynamic vibration reducer according to the theory described above, the following problems arise.

A frictional part enters the Ial device mechanism, and the theoretical effect cannot be obtained.

lbl dynamic vibration absorber is 'Pf + natural frequency of foot (ωd-op
A large-scale adjustment device is required to match the L) and attenuation coefficient (CD-OPT).

Therefore, there are very few examples of application of dynamic vibration absorbers to building structures and bridge structures, and since the vibration targeted by the present invention is in the horizontal direction, from this point of view, it is considered as prior art based on reliable materials. is the following C1ticorp
It is comparable to the equipment in the Center building.

Structure: C4L1corpCen, New York, USA
ter building, height 274m Isometric mass ratio: 1150 Vibration period: 6.5 sec Dynamic vibration absorber: Weight is 400L Concrete block.

Provide an oil film sliding surface. Gussu Uses IJ song hydraulically controlled damper.

Weight stroke ±1.57m.

In this device, a huge weight is installed on the top floor of a building.
It is connected to a fulcrum on the floor via a hydraulic damper, but care is taken to reduce the frictional force mentioned in 1a) above, so an oil film is created and the equipment becomes large-scale. ing. This large-scale device was probably created partly because the target structure of this device was a huge pill, but it was difficult to use it for construction purposes such as suspension bridge main towers due to cost and scale. It is not possible to hire based on the points. For example, if the weight is used for damping the vibration of a main tower of a suspension bridge, the weight of the weight will be several tons.

The device requires some ingenuity in how to slide this weight without causing friction.

The present invention solves the problems of the conventional dynamic vibration reducer, significantly reduces the frictional force acting on the weight, simplifies the mechanism, and makes the dynamic vibration absorber extremely effective as a vibration allocation device for construction work. The purpose is to provide

The pendulum dynamic vibration absorber of the present invention is of a pendulum type in which a weight is suspended, and is controlled by a support frame fixed at or near the top of a structure to be damped, and a line hinge at the upper end. two or more vertically elongated plates facing each other that are attached to the support frame on a plane perpendicular to the direction of vibration and are swingably suspended; It is characterized by comprising a weight attached to each lower part and an attenuator interposed between and connected to two or more adjacent plates of the two or more opposing plates.

The details will be explained below with reference to embodiment figures.

FIG. 4 1al is a perspective view showing the structure of an embodiment of the swing motion vibration absorber of the present invention in which a viscoelastic (or viscous) damper is used as the damper.

A dynamic vibration reducer is installed at a high place at or near the top of the structure to be damped. In FIG. 4 1al, 1 is a support frame fixed to a structure, but if the structural members of the structure itself can be used, they are also included. 2,2
′ denotes two or more weight suspension plates having a vertically elongated shape, each of which is suspended from the swingable support frame 1 on a plane perpendicular to the vibration direction to be controlled by wire hinges 6 and 6′. There is.

The weight suspension plates 2 and 2' face each other in parallel, and can swing only in the direction of vibration to be controlled while always maintaining parallelism. A weight is attached to the bottom of the unit so that the lifting height el can be adjusted.
The weight is divided into parts and the weight suspension plate is sandwiched between them, and the weight is attached using bolts 5.
It is tightened by 5' and fixed to the weight suspension plate. To adjust the hanging height el, loosen the bolts 5.5' and fix the weights to the suspension plates 2 and 2'. This is done by moving up and down inside vertically long holes 8 provided in the suspension plates 2, 2'.

Reference numeral 9 denotes a viscoelastic or viscous material turn bar (attenuator), which is attached to opposing surfaces of the adjacent weight suspension plates 2 and 2' in parallel with the helix hinges 6 and 6' at the upper end of the weight suspension plates, respectively. Bin-10, 10
'The damper is mounted on the shaft so that it can be rotated by the plate 11.
, 11'.

12 is the bolt (the bolt in the lower position is not visible in the figure), and the damper installation connects the plates 11 and 11' and the metal plates 16 and 13' to which the viscoelastic body (or viscous body) is glued, respectively. . The height of the attenuator can be selected at any location that is convenient for construction.

With the above structure, when the weight suspension plate swings as a pendulum, the viscoelastic (viscous material) damper undergoes shearing deformation and can generate a damping force.

Figure 4 1al shows a type in which viscoelastic body (hereinafter also referred to as viscous body) dampers are arranged horizontally as a damper for a pendulum motion vibration absorber, and Figure 4 1al shows a type in which viscoelastic bodies are arranged vertically. . In the case of Fig. 1b), the viscoelastic body (or, as shown in Fig. 1al, is directly connected to the weight suspension plates 2, 2' without going through the damper mounting plate 11, 11).

FIG. 4 1cl shows an installation method when a hydraulic damper is used as a damper for a swing motion vibration absorber.

In the figure, 2.2' is a weight suspension plate, and 14 is a hydraulic damper. The hydraulic damper 14 is rotatably attached at both ends to the weight suspension plates 2, 2' by pins 15, 15' at an inclination t.

In the figure, a is the height of the point, and b is the width, which determines the inclination angle.

When using a viscoelastic damper or a hydraulic damper, dynamic vibration absorption is achieved by adjusting the specifications to obtain the optimum vibration characteristic value depending on the vibration characteristic value of the structure to be damped. Provide the desired damping force to the device. The natural frequency of the device can be determined by adjusting the hanging height el of the weight, the damping coefficient can be determined by adjusting the specifications below the viscoelastic volume in Table 1 when using a viscoelastic damper, and the damping coefficient can be determined by adjusting the damper's volume when using a hydraulic damper. The damping coefficient and installation are determined by adjusting the angle, etc.

According to the structure of the dynamic vibration absorber of the present invention as described above, the following effects can be obtained.

(11 Frictional force is the force obtained by reducing the rotational frictional force at the fixed point of the suspension member and the frictional force of the oil damper by the lever ratio (
Both of them are small, and are estimated to be at least smaller than when Teflon (static friction coefficient of about 0.03) is used for the sliding surface of the weight.

The scale of the +21 device will not be too large and will be of a scale that can be used as an allocation device for the main tower under construction.

Next, the general specifications of the device when the dynamic vibration absorber of the present invention is applied to an actual structure will be described.

υ Target structure: Cable-stayed bridge main tower (height 122m, total weight 1575, deflection 1
Characteristic value of next vibration...MT = 40
LS2/m KT = 168'/m CT "CL261 '"/Long (logarithmic decay rate 'T
= 0.01, the natural frequency of the structure ωT = z 05 rady.

2 Dynamic vibration absorber: The vibration characteristic values are shown in Table-1.

The specifications of the dynamic vibration reducer are calculated from these equations.

First, determine the mass ratio β (β=Md). β-Sat MT
125.

・°・嵵=NT = D, 52 Lsu・°・Wd
= 5.14' The optimal natural frequency ωd*opL is, The suspension height el・opt is, The optimal damping coefficient Cd-opt is ', The required volume V of the viscoelastic body is G2 = 500''//m2 Use materials.

-', V = 1.65XIOm' = 1650
The main parameters wct % cct and e+ of the dynamic vibration absorber were determined as follows by calculations over cm'.

Wd=5.14t Cd=[10712LS/m2(G2=500
．． '/r112 viscoelastic material: 1650 cm'') e+=238 m Based on the above values, it was decided to install four devices of the type shown in Figure 4, 1al.The required value for one device is as shown above. It is a value obtained by dividing Wd and Cd of the parameters into one-fourth.

Wdo = Wd/4 = 785 K&Cd =
0.0178"7m (G2 = 500'/m2
420 cm3 (h = 258 m (no change)) The effect obtained by installing the four dynamic vibration absorbers described above is as follows: The damping of this type of structure is expressed as the logarithmic damping rate δT.
Since δT=101~(102, the damping performance is 10~2
Increased by 0 times, in other words the response amplitude is 1/1o to 1/2o
This means that it has decreased to

[Brief explanation of drawings]

Figure 1 is a vibration model of the structure, Figure 2 is a model of the system with a dynamic vibration absorber installed, Figure 6 is the resonance curve of the structure with the dynamic vibration absorber installed, and Figure 4 1al is the invention of the present invention. An example diagram of a pendulum hole dynamic vibration absorber (a perspective view when a viscoelastic damper is used as the attenuator, Fig. 4 1al is a perspective view of the attenuator part when viscoelastic bodies are arranged vertically, Fig. 4) Figure 1cJ is a side view of the damping 'type part when a hydraulic damper is used as a damper. MT: equivalent mass of the structure, KT: equivalent spring of the structure, CT: equivalent spring of the structure. equivalent attenuation,
... mass of dynamic vibration absorber, cutting ... spring of dynamic vibration absorber, cd
... Damping of dynamic vibration absorber, 1... Support frame,
2, 2'... Weight suspension plate, 6.6'... Line hinge, 4. A... Weight, 5, 5'... Bolt for mounting the weight, 6... Metal fitting for mounting, 7... Bolt for adjusting the weight position, 8... Long hole, 9... Viscoelastic damper (dampener)
, 10 , 10'...pin, 11, 11'...
Damper installation is by plate, 12... Damper installation is by bolt,
13, i3'...Metal plate, 14...Hydraulic damper, 15°15'...Bin. Agent Patent Attorney Saburo Kimura 4th (a) (b)

Claims (1)

[Claims] 1) A support frame fixed at or near the top of the structure to be damped, and the upper end is attached to the support frame by a line hinge on a plane perpendicular to the vibration direction to be controlled. two or more vertically elongated plates facing each other and swingably suspended; a weight attached to the lower part of each of the two or more facing plates; A pendulum hole dynamic vibration absorber comprising a damper interposed between two or more adjacent plates and connecting the two or more plates. 2) The pendulum hole dynamic vibration absorber according to claim 1, characterized in that a viscoelastic material or a viscous material damper is used as the damper. ω The pendulum hole dynamic vibration absorber according to claim 1, characterized in that a hydraulic damper is used as the damper.