JP6164444B2 - Cantilever frame vertical vibration control structure - Google Patents

Description

  The present invention is directed to a cantilever beam structure mainly composed of a cantilever beam having a base end portion supported and a tip end portion being a free end, for reducing vertical vibration of the cantilever beam frame. It relates to the vibration control structure.

This type of cantilever frame is often applied, for example, as a structure of a stand in a stadium (stadium), and on a large scale, the cantilever length (from the support point of the base end to the free end of the tip end) (Projection length) may be 10 m or more.
It is important to be able to sufficiently suppress vibrations in the event of an earthquake from the standpoint of preventing panic as a structural format applied to large-scale structures where an unspecified number of spectators gather such as stadium facilities However, since the cantilever frame as described above basically does not necessarily have a high natural frequency in the vertical direction, it is not easy to effectively suppress the vertical vibration.

  As a vibration suppression technique for a structure, for example, TMD as disclosed in Patent Document 1 is widely known. This is intended to reduce the vibration effect by oscillating the additional mass installed in the structure to be damped so as to synchronize with the vibration period of the structure, but this type of TMD is generally 500 kg to 1 ton. Since an additional mass is required, there is a problem that a large burden is applied to the structure to be controlled.

Therefore, for example, as shown in Patent Documents 2 to 4, a tuning-type damping mechanism is proposed that can obtain a damping effect equal to or higher than that of conventional TMD even with a small mass by using a rotary inertia mass damper. ing.
As is well known, a rotary inertia mass damper can exhibit a mass effect of several hundred to several thousand times the mass of a rotary weight using the rotary inertia mass effect. Specifically, by converting the linear motion due to the vibration of the object to be controlled to the rotational motion of the rotating weight using the ball screw mechanism, the rotating weight is caused by the reaction force proportional to the rotating inertia moment generated in the rotating weight. A large mass effect can be obtained by enlarging the actual mass of the material to several hundred to several thousand times.
An element that functions as a tuning spring for such a rotary inertia mass damper (in addition to a special spring element, the spring rigidity of a member for installing the rotary inertia mass damper can also be used in series). The additional vibration system is configured to be provided at the same time, and the vibration characteristics of the additional vibration system are synchronized with the structure to be controlled so as to function as a TMD. Only by using a small and lightweight rotating weight having a mass of one hundredth to several thousandth, an excellent vibration damping effect equivalent to or better than the original TMD can be obtained.

  As a technique for obtaining a damping effect by applying the TMD using the rotary inertia mass damper as described above to a cantilever beam frame, a beam vibration reduction mechanism shown in Patent Document 5 has been proposed.

JP-A-10-252253 JP 2008-115552 A JP 2010-38318 A JP 2011-122345 A JP 2012-167438 A

However, the vibration control mechanisms disclosed in Patent Documents 2 to 5 cannot be simply installed on the large-scale cantilever frame as described above. In particular, what is disclosed in Patent Document 5 is intended for a cantilever beam frame, but obtains a vibration damping effect indirectly not through the cantilever beam itself but through another beam connected behind it. It is difficult to effectively apply to a cantilever frame installed in the form of a stand in a stadium.
Thus, at present, an effective and appropriate method capable of suppressing the vertical vibration of a large-scale cantilever frame has not been established, and the actual situation is still in the search stage.

In view of the above circumstances, the invention according to claim 1 is directed to a cantilever frame mainly composed of a cantilever beam having a base end portion supported and a tip end portion defined as a free end. A vertical vibration control structure of a cantilever frame for reducing vibration in the vertical direction, wherein the side of the cantilever is shorter than the cantilever , the base end is supported, and the distal end is a free end And a damper supporting beam that can vibrate relative to the cantilever beam is installed along the cantilever beam, and rotational inertia is provided between a tip portion of the damper supporting beam and an intermediate portion of the cantilever beam. It is characterized in that the natural frequency of the additional vibration system by the damper support beam and the rotary inertia mass damper is tuned to the natural frequency of the cantilever beam frame with a mass damper interposed therebetween. .

  According to a second aspect of the present invention, in the vertical vibration damping structure of the cantilever frame according to the first aspect, the damper support beam functions as a tuning spring connected in series to the rotary inertia mass damper. The spring rigidity in the vertical direction is set.

  The invention according to claim 3 is the vertical vibration damping structure of the cantilever frame according to claim 1 or 2, wherein the additional vibration system includes a tuning spring connected in series to the rotary inertia mass damper. It is characterized by this.

  According to the present invention, the damper support beam is installed along the side portion of the cantilever beam to be damped, and the rotary inertia mass damper is interposed between the damper support beam and the cantilever beam. The vertical vibration of the entire cantilever frame can be sufficiently suppressed by the tuning-type additional vibration system constituted by the support beam and the rotary inertia mass damper. Therefore, the present invention is extremely effective and rational as a vertical vibration control structure for a large cantilever frame such as a stand in a stadium.

The embodiment of the up-and-down damping structure of the present invention is shown, and is a side view showing the cantilever frame to be controlled. It is a figure which shows the example of a structure of an additional vibration system similarly, (a) is a side view, (b) is the bb line view enlarged view in (a). FIG. 2 shows a specific design example, where (a) is a plan view shown as an analysis model for vibration analysis, and (b) is a diagram showing specifications of an additional damping mechanism. FIG. 6 is a diagram showing vibration characteristics, where (a) shows a transfer function for acceleration and displacement in the case of non-vibration suppression (comparative example), and (b) shows acceleration and displacement in the case of vibration suppression (this embodiment). The transfer function for displacement is shown. It is a figure which shows a maximum response value similarly, (a) is a figure which shows the maximum acceleration and the maximum displacement in the span center part in the front-end | tip part of a cantilever beam frame, (b) is a span in the front-end | tip part of a cantilever beam frame. It is a figure which shows the maximum acceleration and the maximum displacement in the position deviated from the center part. It is a figure which shows an acceleration response waveform similarly, (a) is a figure which shows the acceleration response waveform in the span center part in the front-end | tip part of a cantilever frame, (b) is the span center part in the front-end | tip part of a cantilever frame. It is a figure which shows the acceleration response waveform in the position deviated from.

  With reference to FIGS. 1-6, the vertical vibration damping structure of the cantilever frame which is embodiment of this invention is demonstrated. FIG. 1 is a diagram illustrating a cantilever frame 1 to be controlled, and FIGS. 2A and 2B are diagrams illustrating a configuration example of an additional vibration system 10 attached thereto.

  The cantilever frame 1 to be damped in the present embodiment is provided as a frame of a large-scale stadium stand, and is a steel structure having a base end portion supported by a column 2 and a tip end portion being a free end. The cantilever 3 is mainly used, and a step-like slab 4 is provided on the upper part thereof. Reference numeral 5 denotes a large beam erected between the pillars 2, and reference numeral 6 denotes a front end small beam erected between the end portions of the cantilever 3 (see FIG. 3A).

  The additional vibration system 10 in this embodiment is for suppressing the vertical vibration of the entire cantilever frame 1 including the slab 4 by reducing the vertical vibration of the cantilever 3 described above. As shown in FIG. 2 (b), the damper support beam 11 installed on the side of the cantilever 3 is attached to the side, and as shown in FIG. 2 (a), the tip of the damper support beam 11 and the cantilever The rotary inertia mass damper 12 is interposed between the beam 3 and the main body.

  The damper support beam 11 is a steel truss beam shorter than the cantilever 3 to be damped, and this damper support beam 11 is also in the form of a cantilever beam similar to the above cantilever beam 3 (that is, the base end portion is the same). The damper support beam 11 is supported by the above-described pillar 2 or the large beam 5 in the vicinity thereof, and the tip portion is a free end. The damper support beam 11 has vibration characteristics compared to the cantilever beam 3 to be controlled. They are different from each other and can be relatively vibrated in the vertical direction with respect to the cantilever 3.

  The rotary inertia mass damper 12 is a well-known one using a ball screw mechanism, for example, similar to those shown in Patent Documents 2 to 5, and as shown in FIG. At the position (in the illustrated example, a position slightly on the tip side from the central position in the length direction), it is connected to the cantilever 3 via the bracket 13 as shown in FIG. The front end of the damper support beam 11 is connected to the upper end of the damper support beam 11 via a tuning spring 14 made of a leaf spring.

  The rotary inertia mass damper 12, the above-described tuning spring 14 and the damper support beam 11 are structurally connected in series, and the whole forms a tuning-type additional vibration system 10. In addition, by synchronizing the natural frequency of the additional vibration system 10 with the natural frequency of the cantilever frame 1 to be controlled, the additional vibration system 10 effectively suppresses the vertical vibration of the cantilever 3. It is like that.

The additional vibration system 10 can be tuned only by setting the spring rigidity in the vertical direction of the damper support beam 11. In this case, the above-described tuning spring 14 is omitted and the rotary inertia mass damper 12 is supported by the damper. It is also possible to connect to the beam 11 in a fixed state.
In addition, it is also preferable to give the additional vibration system 10 an appropriate damping function as necessary. For this purpose, a rotary inertia mass damper 12 having a damping function is used, or an appropriate damping element such as an oil damper is used. What is necessary is just to provide in parallel with respect to the rotation inertia mass damper 12. FIG.

  When the cantilever frame 1 to be controlled is vibrated by an earthquake or by walking or movement of a spectator as an overload, the additional vibration system 10 having the above configuration is vertically moved between the cantilever 3 and the damper support beam 11. Relative vibration occurs, and the rotary inertia mass damper 12 is actuated, and the rotary inertia mass acts on the cantilever 3 as a damping force. Therefore, the additional vibration system 10 functions as a TMD and functions as a cantilever. An excellent vibration damping effect for the frame 1 can be obtained.

In this case, it is effective that the rotational inertia mass damper 12 is installed as close to the tip of the cantilever 3 as possible (that is, a position where vertical vibration is significantly generated). It is most effective to make the length of the damper support beam 11 as long as that of the cantilever beam 3 and to interpose the rotary inertia mass damper 12 between the two end portions.
However, since the damper support beam 11 is also installed in the form of a cantilever beam similarly to the cantilever beam 3 to be damped, if the length of the damper support beam 11 is made equal to that of the cantilever beam 3, a desired spring rigidity can be obtained. If both of them are of equal length, the structural behavior will be equivalent and they will vibrate synchronously, in which case it will be difficult to produce significant relative vibrations, and the rotary inertia mass damper 12 cannot operate effectively.
Therefore, as shown in the illustrated example, the damper support beam 11 is made shorter than the cantilever beam 3 so as to have a relatively higher rigidity than the cantilever beam 3 and the spring rigidity is appropriately set. It is realistic to make a tuning so that the rotational inertia mass damper 12 is reliably operated by making a significant difference between the vibration characteristics of the cantilever 11 and the cantilever 3 and the relative vibration is surely generated between them. This also provides a sufficient vibration control effect.

  Hereinafter, a specific design example of the vertical vibration control structure of the present invention will be shown with reference to FIGS. 3 to 6, and its effectiveness will be verified by a vibration analysis result. For comparison, the case where the additional vibration system 10 is not installed (in the case of non-vibration suppression) is also shown.

FIG. 3A is a plan view showing a part of the cantilever frame 1 as an analysis model. An additional vibration system 10 including a damper support beam 11 and a rotary inertia mass damper 12 is provided on the side of the cantilever 3. They are installed together.
As shown in FIG. 3A, the center position of the small end beam 6 laid between the end portions of the cantilever 3 (that is, the center position of the end of one span by the two cantilever beams 3) is point A. The vibration control effect is evaluated with the position deviated slightly to the side as B point and the A point and B point as evaluation points for response.
The specifications of the additional vibration system 10 are as follows. As shown in FIG. 3B, the inertial mass of the rotary inertial mass damper 12 is 13.4 tons, the tuning spring is 1.03 × 10 ⁷ N / m as the spring rigidity of the damper support beam 11 itself, The attenuation coefficient was 8.90 × 10 ⁴ Ns / m.

In order to analyze the frequency transfer characteristics, a sweep waveform is given as seismic motion, and the vibration characteristics of the cantilever frame 1 are examined by calculating the spectral ratio of response to input. The sweep wave is 2 to 8 Hz (log scale, duration 396.56 seconds), and the amplitude is 1 m / s ² . The time step was 0.005 seconds and the damping was proportional to the initial stiffness proportional to 1% of the primary natural frequency.

FIG. 4 shows vibration characteristics (transfer functions for acceleration and displacement) in each part of the cantilever frame 1. 4A shows a case where the additional vibration system 10 is not installed (non-vibration suppression), and FIG. 4B shows a case where the additional vibration system 10 is installed (vibration suppression).
In the case of non-damping, a large peak occurs at the primary natural frequency of 4.2 Hz, but in the case of damping, the resonance peak is significantly reduced.

5 and 6 show the maximum response value and response waveform when the seismic motion is input in the vertical direction. As the earthquake motion, Taft UD and Kokuji UD (notification wave (Kobe phase)) were used (UD indicates the vertical movement of the observed wave).
FIG. 5 (a) shows the maximum response value at point A by Taft UD, and FIG. 5 (b) shows the maximum response value at point B by Kokuji UD. 6A shows an acceleration response waveform at point A by Taft UD, and FIG. 6B shows an acceleration response waveform at point B by Kokuji UD.
It can be seen that in both cases, the seismic response is reduced in the case of vibration suppression compared to the case of non-vibration suppression.

As described above, according to the present invention, the damper support beam 11 is provided along the side portion of the cantilever 3 to be damped, and is rotated between the damper support beam 11 and the cantilever 3. By constructing the tuned additional vibration system 10 with the inertia mass damper 12 interposed therebetween, the vertical vibration with respect to the entire cantilever frame 1 can be largely suppressed.
Therefore, the present invention is extremely effective and rational as a vertical vibration control structure for a large cantilever frame such as a stand in a stadium.

  As mentioned above, although embodiment of this invention was described, the said embodiment is an example to the last, Comprising: The specific structure and specification of the additional vibration system 10 in this invention are the structures of the cantilever frame 1 of a damping object. It may be optimally designed so as to obtain a desired effect in accordance with the scale, application, basic vibration characteristics and required vibration performance, and other various conditions, and as long as it is limited to the above embodiment. Naturally, appropriate design changes can be made without any problem.

DESCRIPTION OF SYMBOLS 1 Cantilever frame 2 Column 3 Cantilever 4 Slab 5 Large beam 6 Small end beam 10 Additional vibration system 11 Damper support beam 12 Rotary inertia mass damper 13 Bracket 14 Tuning spring

Claims (3)

A cantilever frame for reducing a vertical vibration of a cantilever beam structure mainly composed of a cantilever beam whose base end part is supported and whose front end part is a free end. The vertical vibration control structure of
A damper supporting beam, which is shorter than the cantilever, has a base end supported and a distal end is a free end, and can vibrate relative to the cantilever on the side of the cantilever. In addition, a rotational inertia mass damper is interposed between a tip portion of the damper support beam and an intermediate portion of the cantilever beam, and additional vibration is generated by the damper support beam and the rotary inertia mass damper. A vertical vibration damping structure for a cantilever beam structure, wherein the natural frequency of the system is synchronized with the natural frequency of the cantilever beam frame.   The cantilever according to claim 1, wherein the damper support beam has a spring rigidity in the vertical direction so as to function as a tuning spring connected in series with the rotary inertia mass damper. Vertical vibration control structure of the frame.   The vertical vibration damping structure for a cantilever frame according to claim 1 or 2, wherein the additional vibration system includes a tuning spring connected in series with the rotary inertia mass damper.

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