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Vibration Control of Structures with Multiple Tuned Mass Dampers Considering System Interaction Effects
Structural Vibration Control
Multiple Tuned Mass Dampers
Torsionally Coupled Effect
Soil-Structure Interaction Effect
|摘要:||裝設主/被動結構振動控制系統以降低結構受如強風、地震及人為等外力作用下之動態反應，已引起國內外學術界與工程界的研究興趣，其中被動調諧質量阻尼器(Passive Tuned Mass Damper, PTMD)由於近年來廣泛的理論與實驗探討，使得此裝置不論是用於新建結構與設備以增進安全與使用功能，或是用於現存耐震能力不足結構之補強，均得到各界越來越多之肯定。然而，無論新舊結構，欲裝設PTMD，均需瞭解原主結構之動態特性，方能進行PTMD之最佳設計。PTMD之振動控制效用，主要藉由設計其頻率調諧(Tune)於原主結構之主要頻率而達到消能減振之目的，因此，當PTMD未調諧至正確之頻率時，將產生離頻效應導致PTMD失去應有之減振功能。為減少離頻效應，可從準確識別原主結構動態特性或減低控制裝置對頻率變化之敏感度兩方面著手。
由於PTMD為一單自由度系統，對結構頻率變化之敏感度很高，當此裝置應用於具系統互制效應之結構時，例如列車-橋梁互制系統、土壤-結構互制系統等，將由於對系統特性之估算不準使裝設之PTMD喪失效用。因此，本文第二部分即針對上述二種具系統互制效應之結構模式進行探討，以了解忽略互制效應產生之結果。本文接著發展一套多元調諧質量阻尼器(Multiple Tuned Mass Damper, MTMD)之最佳設計準則，並應用於此二結構互制系統，期能藉由此裝置具寬頻之特性，減少離頻效應之影響。
In recent years, the use of active and passive control devices such as Passive Tuned Mass Damper (PTMD) to reduce the dynamic responses of structures under strong environmental loadings has become an area of considerable research interest. Due to recent intensive analytical and experimental studies, vibration control of structures using PTMDs is gaining more acceptance not only in the design of new structures and components but also in the retrofit of existing structures to enhance their reliability against winds, earthquakes and human activities. Basically, a PTMD is a device consisting of a mass connected to structures using a spring and a viscous damper. The PTMD has the control effectiveness by tuning its frequency to the primary structural frequency. Therefore, it is generally recognized that the design of an optimal PTMD requires a prior knowledge of the modal parameters of the controlled structure to achieve the desired vibration control effectiveness. In practical applications, the PTMD probably does not tune to the right frequency, so that the detuning effect deteriorating the PTMD control effectiveness will occur. In the first part of this thesis, the vibration control philosophy and optimal design of passive tuned mass dampers (PTMDs) for a multi-degree-of-freedom (MDOF) structure are presented. In order to accurately evaluate the structural parameters and prove the effectiveness of PTMD, an modal parameters identification technique is intruduced to calculate the modal frequencies, damping ratios, and mode shapes based on only a few floor response measurements. Numerical results throughout a five-story building under ambient random excitations demonstrated that the proposed system identification techniques are able to identify the dominant modal parameters of the system accurately, even with high closed-space frequencies and noise contamination. To assess structural dynamic responses more accurately, many exact mathematical models were proposed and the error of conventional structural models was estimated carefully. It is found that the system interaction effect, such as vehicle-bridge interaction and soil-structure interaction, will modify the original properties of structures even if the structural materials are maintained within the linear range. In the second of this thesis, these interaction effects are further investigated to avoid overestimation of PTMD control performance. With the understanding of system interaction effect, this study pays much effect on the determination of the optimal MTMD system parameters. The MTMDs are then applied to reduce vibration of train-bridge interaction system and soil-structure interaction system. From the numerical investigations about the Taiwan High Speed Railway bridge and irregular buildings on soils, it is proved that the MTMD is more effective than single PTMD.
|Appears in Collections:||土木工程學系所|
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