Development of Active Vibration Damping Device Adjusting TMD to Various Periodic Bands of Seismic Waves

2019 ◽  
Author(s):  
Kota Watanabe ◽  
Nanako Miura ◽  
Akira Sone
Keyword(s):  
Urban Areas ◽  
Seismic Waves ◽  
Basic Research ◽  
Large Earthquake ◽  
Active Device ◽  
Construction Period ◽  
High Rise ◽  
Mass Damper ◽  
Active Vibration Damping ◽  
Active Vibration

Abstract There are many high-rise buildings all over the world, especially urban areas. Their usage is diverse, such as offices and residences. Therefore, earthquake countermeasures for high-rise buildings are indispensable. It is known that a tuned mass damper (TMD), which is mainly installed for countermeasures against wind shaking, does not show sufficient damping effect when large earthquake occurs or when higher modes vibration is excited. In addition, when exceeding the drive limit of the TMD in resonance, the TMD may collide against the stopper and deteriorate the response of the building. There are some researches targeting building with TMD, and many of them aim at developing new devices. However, installing a new equipment instead of TMD requires a lot of cost and construction period. Therefore, in this research, an active device that can be attached to TMD is developed. Moreover, validity is examined by numerical simulation. In this paper, parameters of the passive elements are verified as a basic research of the proposed device.

scholarly journals A Bufferable Tuned-Mass Damper of an Offshore Platform against Stroke and Response Delay Problems under Earthquake Loads

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Qiong Wu ◽  
Xilu Zhao ◽  
Shuai He ◽  
Wenxian Tang ◽  
Rencheng Zheng
Keyword(s):  
Seismic Waves ◽  
Large Earthquake ◽  
Tuned Mass Damper ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Response Delay ◽  
Earthquake Loads ◽  
Response Characteristics ◽  
Mass Damper ◽  
Dynamic Performances

A tuned-mass damper (TMD) is applied to ensure the safety and stability of an offshore platform in practice; however, damper stroke and response delay problems always result in intractable performances of vibration control while exposed to large earthquake loads. Therefore, this paper proposes a bufferable TMD, a passive TMD with buffers on both sides, to improve the performance of offshore platforms subjected to large seismic waves. A comprehensive simulation and experimental study was executed to investigate the dynamic performances of the bufferable TMD, by application of a 1 : 200-scale offshore platform prototype. It is verified that the bufferable TMD can be effective in absorbing the stroke energy, while the damper exceeds limitations of motion. Meanwhile, the bufferable TMD can maintain high-response characteristics. In conclusion, the experimental results indicate that the displacement, acceleration, and frequency performances of an offshore platform can be significantly decreased, and the evaluation indices show that the method is effective in reducing overall vibration levels and maximum peak values, with the application of the bufferable damper system.

scholarly journals A Quantitative Method for Evaluation of Visual Privacy in Residential Environments

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 272
Author(s):  
He Zheng ◽  
Bo Wu ◽  
Heyi Wei ◽  
Jinbiao Yan ◽  
Jianfeng Zhu
Keyword(s):  
Urban Areas ◽  
Architectural Design ◽  
Ground Level ◽  
High Density ◽  
Rapid Expansion ◽  
High Rise ◽  
Visual Exposure ◽  
Building Management ◽  
Visual Privacy ◽  
Building Level

With the rapid expansion of high-rise and high-density buildings in urban areas, visual privacy has become one of the major concerns affecting human environmental quality. Evaluation of residents’ visual exposure to outsiders has attracted more attention in the past decades. This paper presents a quantitative indicator; namely, the Potential Visual Exposure Index (PVEI), to assess visual privacy by introducing the damage of potential visual incursion from public spaces and neighborhoods in high-density residences. The method for computing the PVEI mainly consists of three steps: extracting targets and potential observers in a built environment, conducting intervisibility analysis and identifying visible sightlines, and integrating sightlines from building level and ground level to compute the PVEI value of each building opening. To validate the proposed PVEI, a case study with a sample building located at the center of Kowloon, Hong Kong, was evaluated. The results were in accordance with the common-sense notion that lower floors are subjected to poor visual privacy, and privacy is relatively well-preserved in upper floors in a building. However, residents of middle floors may suffer the worst circumstances with respect to visual privacy. The PVEI can be a useful indicator to assess visual privacy and can provide valuable information in architectural design, hotel room selection, and building management.

scholarly journals Seismic Resistance and Parametric Study of Building under Control of Impulsive Semi-Active Mass Damper

2021 ◽  
Vol 11 (6) ◽  
pp. 2468
Author(s):  
Ming-Hsiang Shih ◽  
Wen-Pei Sung
Keyword(s):  
Frequency Ratio ◽  
Efficiency Index ◽  
Reduction Ratio ◽  
Seismic Resistance ◽  
Control Effect ◽  
Active Mass ◽  
High Rise ◽  
Mass Damper ◽  
Active Mass Damper ◽  
External Forces

When high-rise buildings are shaken due to external forces, the facilities of the building can be damaged. A Tuned Mass Damper (TMD) can resolve this issue, but the seismic resistance of TMD is exhausted due to the detuning effect. The Impulsive Semi-Active Mass Damper (ISAMD) is proposed with fast coupling and decoupling at the active joint between the mass and structure to overcome the detuning effect. The seismic proof effects of a high-rise building with TMD and ISAMD were compared. The numerical analysis results indicate that: (1) the reduction ratio of the maximum roof displacement response and the mean square root of the displacement reduction ratio of the building with the ISAMD were higher than 30% and 60%, respectively; (2) the sensitivity of the efficiency index to the frequency ratio of the ISAMD was very low, and detuning did not occur in the building with the ISAMD; (3) to achieve stable seismic resistance of the ISAMD, its frequency ratio should be between 2 and 4; (4) the amount of displacement of the control mass block of the ISAMD can be reduced by enhancing the stiffness of the auxiliary spring of the ISAMD; and (5) the proposed ISAMD has a stable control effect, regardless of the earthquake distance.

Modale Regelung von Werkzeugmaschinen*/Modal control for machine tools

2019 ◽  
Vol 109 (05) ◽  
pp. 358-364
Author(s):  
C. Peukert ◽  
P. Pöhlmann ◽  
S. Ihlenfeldt ◽  
J. Müller ◽  
M. Merx
Keyword(s):  
Machine Tools ◽  
Vibration Damping ◽  
Modal Control ◽  
Modal Approach ◽  
Active Vibration Damping ◽  
Active Vibration

Vorschubachsen von Werkzeugmaschinen werden oft mit mehreren, parallel wirkenden Antrieben ausgestattet. Auch zusätzliche Aktoren für die aktive Schwingungsdämpfung kommen zunehmend zum Einsatz. Im Beitrag wird die modale Regelung für Werkzeugmaschinen vorgestellt. Sie ermöglicht es, die Eigenformen individuell zu regeln und die angeregten Schwingungen mit allen verfügbaren Aktoren gezielt zu bedämpfen. Es werden Ergebnisse zur modalen Regelung am Beispiel einer Gantry-Anordnung vorgestellt.   Feed axes of machine tools are often equipped with several parallel acting drives. Additional actuators for active vibration damping are also increasingly used. This article introduces the modal control for machine tools. The modal approach enables the eigenmodes to be controlled independently and the excited vibrations to be damped specifically with all available actuators. The results for the modal control of a gantry arrangement are presented as an example.

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