應用黏性阻尼器於三維建築結構之最佳化分配研究

Abstract

黏性阻尼器(Viscous Damper)經常被應用於建築結構作為被動消能元件，但目前的規範中，對於黏性阻尼器之配置方法較無具體的規定與建議。此研究之目的為利用三維建築模型去尋找黏性阻尼器之最佳化分配，期望使阻尼器可有效發揮其功用，降低結構物於地震下之反應。 本研究整理現有阻尼器分配法將之分為直接分配法及動力分析分配法。設計過程中直接藉由結構物本身特性進行分配，不須經過動力分析之分配法為直接分配法；而設計過程須經過動力分析之分配法為動力分析分配法。 推廣至三維建築模型時，結構質心與剛心可能不重合，面對此偏心結構，阻尼器的設計不再是各樓層的阻尼係數的配置，須額外考慮在各樓層平面中阻尼器擺放的位置，因此本文引入「臨界偏心率」的概念，分析各阻尼器分配法之臨界偏心率，進而得到結構平面中阻尼擺設的策略為:結構偏心小於臨界偏心率採用異側阻尼擺設，而結構偏心大於臨界偏心率採用同側阻尼擺設。 藉由將真實地震擬合至6種地震工址反應譜之人工合成地震，進行線性動力歷時分析及非線性動力歷時分析，得到最佳阻尼分配法為Lavan法，同時也可觀察出阻尼配置分布於中低樓層是較好的配置方式，但仍建議使用多種分配法分別來分配阻尼器並通過數值模型檢核並選出較適合該建築物之分配法。另外為簡化結論以利於工程師做參考，本文亦針對Lavan法作臨界偏心率之修正，，當阻尼比為10%時，使用Lavan法之臨界偏心率為5%；當阻尼比為20%時，用Lavan法之臨界偏心率為15%。

Viscous damper is often used in building structures as passive energy dissipation devices. However, the issue of the efficient placement of viscous dampers has received less attention in existing codes. The purpose of this research is to find the optimal allocation of viscous dampers by using three-dimensional building model, and expecting the viscous dampers work more efficiently with optimal allocation under seismic forces. In this study, there are five existing distribution methods divided into two groups, “Direct Distribution Method” and “Dynamic Analysis Distribution Method”. The method that allocate viscous dampers based on structure properties without dynamic analysis are called “Direct Distribution Method”, with dynamic analysis are called “Dynamic Analysis Distribution Method”. When extended to three-dimensional building models, the center of mass and the center of rigidity might not coincide. For these eccentric structures, the design of dampers should not only consider the allocation of damper coefficient but also the position of each damper in each floor. Therefore, we introduce “Critical Eccentricity Ratio” to obtain the strategy of damper arrangement with all distribution methods. If the structural eccentricity is smaller than critical eccentricity ratio, we should apply damper arrangement on the opposite side. On the contrary, apply damper arrangement on the same side if the structural eccentricity is greater than critical eccentricity ratio. Through the results of six artificial earthquakes generated from response spectrums of different districts, we found out that “Lavan method” is the best method within all models by carrying out the linear dynamic analysis and non-linear dynamic analysis. Nevertheless, it is still suggested that better to use several distribution methods together in the design model and then find the most suitable allocation method. For further investigation, the research simplified the rule of critical eccentricity ratio of Lavan method. When damping ratio of Lavan method is 10%, the modified critical eccentricity ratio is 5%; when damping ratio of Lavan method is 20%, the modified critical eccentricity ratio is 15%.