JPH03213742A - Multipledegree-of-freedom dynamic vibration damper - Google Patents

Abstract

PURPOSE:To absorb not only the primary but also the following natural periods of earthquake energy by a dynamic vibration damper so as to reduce the response of a structure efficiently by adjusting plural weights and springs according to each vibration mode of the structure. CONSTITUTION:A multidegree-of-freedom dynamic vibration reducer is formed of plural weights and plural springs for supporting the respective weights, and the spring to each weight is adjusted according to the primary and the following characteristic frequency of a structure. The weights 2, 4 are formed of rectangular parallelepipeds made of steel or concrete, and the springs 3, 5 are made of cylindrical highly damping rubber bodies. In this case, the spring value is adjusted by changing the number of rubber bodies and the like. By using the multipledegree-of-freedom dynamic vibration damper, the reducing effect of relative displacement and absolute acceleration is large at both material points 1, 2. The absolute acceleration of the material point 1 and the relative displacement and absolute acceleration of the material point 2 that cannot be reduced by a single dynamic vibration damper can be thus reduced efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dynamic vibration absorber for reducing the response of a structure caused by external forces such as earthquakes and wind.

[Conventional technology]

Dynamic vibration absorbers have traditionally been used in the mechanical field primarily to counter mechanical vibrations, but they are also being applied in the architectural field to suppress building vibrations caused by wind and earthquakes. In addition to the basic dynamic vibration absorber consisting of a weight, a spring, and a damper, there are various types such as a sloshing damper (see Japanese Patent Application Laid-Open No. 101764/1982), a pendulum type dynamic vibration absorber (see Japanese Patent Application Laid-Open No. 63-254247), etc. A type of dynamic vibration absorber has been developed.

[Problem to be solved by the invention] By the way, the conventional dynamic vibration absorber for structures is a single dynamic vibration absorber, and as shown in the model diagram of Fig. 2(b), one mass point is placed at the top of the building. A honey mass is provided to reduce the primary phase component of the building's response. This is shown in Figure 3 (
In the comparison of the transfer functions shown in a) and (b), this corresponds to the fact that the left peak (first-order period) in FIG. 3(b) is considerably smaller.

However, as is clear from the figure, the peak on the right (secondary period)
No reduction effect was observed for

In the present invention, by configuring a multi-degree-of-freedom dynamic vibration absorber with two or more degrees of freedom in place of a single dynamic vibration absorber with one degree of freedom, the response of the building to external disturbances such as earthquakes can be further reduced and the efficiency can be improved. The purpose is to carry out enforcement.

[Means for Solving the Problems] The multi-degree-of-freedom dynamic vibration absorber of the present invention consists of a plurality of weights installed on a structure and a plurality of springs supporting each weight. It is adjusted according to the natural frequencies from the first order to the several orders.

Although it depends on the vibration characteristics of the building, the simplest structure is 2.
It has a structure in which two weights are connected in series to the structure with two springs.

The material, shape, and size of the weight and spring are not particularly limited, and can be designed in the same way as a conventional single dynamic vibration absorber, taking into account installation space, installation efficiency, economic efficiency, etc. .

[Example] Figure 2 (a) shows a structure with two mass points (M., ) and (M.
O2) and two springs (Kol, hoe), (Ko
2. This is an analytical model (basic model) expressed as ho2).

On the other hand, Fig. 2(b) is an analysis model of a conventional single dynamic vibration absorber. (m2
．． ) and a spring (kzl.) connecting the weight and the structure.

hz+). In addition, Fig. 2 (C) is an analytical model of the multi-degree-of-freedom dynamic vibration absorber of the present invention, which includes two additional masses (m, , ), (m, 2) as weights, and the structure of these two weights. Two springs (kz, h
z), (k+z, htz).

In the above analytical model, the weight of the two mass points of the structure is M
o+=Mog=392t, spring rigidity Ko+=20t/
Cm, Koz=30t/cm, attenuation rate h o1= h
oz=1%, weight of single dynamic vibration absorber weight mz+=7.
84t, spring stiffness k 2I=0.20t/cm, damping rate 11g+=10%, first and second of multi-degree-of-freedom dynamic vibration absorber
The weight of the weight m 11 = m 1□ = 3.92 t
, spring stiffness 1+=o, 20t/cm, k+z=o,
30t/cm and a damping rate h+t=hrz=10%, the analysis results are shown in FIGS. 3(a) to 7(C) and FIGS. 4 to 7. In addition, in this case, Figure 2 (
The first-order natural period T in the basic model of a) is 1.2
6 seconds, and the secondary natural period T2 is 0.51 seconds.

Figures 3(a) to (C) are respectively similar to Figures 2(a) to (C).
This shows the frequency transfer function of mass point 1 with respect to ground motion corresponding to the analytical model of On the other hand, as shown in Figure 3 (C), in the multi-degree-of-freedom (two-degree-of-freedom) dynamic vibration absorber, the peaks of the acceleration response magnification corresponding to the first and second natural frequencies decrease. ing.

Figures 4 and 5 are Figures 2(a) and 2, respectively.
Regarding the analytical model in Figure (C), the relative displacement and absolute acceleration of mass point 1 of the structure when 100 Gal of El Centro NS components are input as seismic waves are shown as a response time history. In the figure, the solid line represents the case where the multi-degree-of-freedom (two-degree-of-freedom) dynamic vibration absorber of the present invention is installed, and the dotted line represents the case where only the structure is installed. 6 and 7 similarly show the relative displacement and absolute acceleration of the mass point 2 of the structure as a response time history.

In addition, Figures 8 to 11 are shown in Figure 2 (b) and Figure 2 (
Regarding the analytical model C), response time histories similar to those shown in FIGS. 4 to 7 are shown. In the figure, the dotted line indicates the case where a single dynamic vibration absorber is installed, and the solid line indicates the case where the multi-degree-of-freedom (two degrees of freedom) dynamic vibration absorber of the present invention is installed.

These figures show that when using the multi-degree-of-freedom dynamic vibration absorber of the present invention, the effect of reducing the relative displacement and absolute acceleration at both mass points 1 and 2 is large, and the absolute acceleration of mass point 1, which cannot be reduced with a single dynamic vibration absorber, It can be seen that there is a large reduction effect on the relative displacement and absolute acceleration of the mass point 2.

Figure 1 shows an example of a specific structure of a two-degree-of-freedom dynamic vibration absorber, in which the weights 2 and 4 are rectangular parallelepipeds made of copper or concrete, and the springs 3 and 5 are cylindrical high-damping rubber. I am using it. In this case, the spring value can be adjusted by, for example, changing the number of rubber pieces.

〔Effect of the invention〕

In the multi-degree-of-freedom dynamic vibration absorber of the present invention, multiple weights and springs are adjusted according to each vibration mode (natural period) of the target structure. Dynamic vibration absorbers can also absorb seismic energy with respect to the natural period and efficiently reduce the response of the structure.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram showing an embodiment of the multi-degree-of-freedom dynamic vibration absorber of the present invention, and Figures 2 (a) to (C) are a structure, a structure provided with a single dynamic vibration absorber, and a structure of the present invention. An analytical model diagram of a structure equipped with a multi-degree-of-freedom dynamic vibration absorber, Figures 3 (a) to (C) are graphs of the frequency transfer function of mass point 1 for the analytical model of Figures 2 (a) to (C), respectively. , Figures 4 to 7 show comparative examples of the basic model and the multi-degree-of-freedom dynamic vibration absorber of the present invention.
Figures 6 and 7 are graphs using the relative displacement and absolute acceleration of mass point 2 in the analysis as response time histories, respectively, and Figures 8-
Similarly, FIG. 11 shows a comparative example of a conventional single dynamic vibration absorber and a multi-degree-of-freedom dynamic vibration absorber of the present invention.
The figures are graphs in which the relative displacement and absolute acceleration of mass point 1 in the analysis are used as the response time history, and Figures 10 and 11 are graphs in which the relative displacement and absolute acceleration of mass point 2 in the analysis are respectively used as the response time history. 1... Structure, 2, 4... Weight, 3.5... Spring (a) Figure (b) (C) Figure (a) (b) (C)

Claims (3)

[Claims] (1) Consists of a plurality of weights installed on a structure and a plurality of springs that support each of the weights, and the springs for each of the weights are adjusted according to the first to several natural frequencies of the structure. A multi-degree-of-freedom dynamic vibration absorber. (2) The multi-degree-of-freedom dynamic vibration absorber according to claim 1, wherein the plurality of weights are connected in series to the structure by the spring. (3) The multi-degree-of-freedom dynamic vibration absorber according to claim 1 or 2, wherein the spring is made of a plurality of cylindrical high-damping rubber pieces.