Optimal Placement of Dampers in Building Structures With Non-classically Damped System
Date Issued
2014
Date
2014
Author(s)
Liao, Chun-Man
Abstract
In order to reduce the vibration of structures, buildings are designed to resist earthquakes by active or passive energy dissipation devices. The current codes such as FEMA 273/274 suggested the equivalent damping ratio, but the development of efficient procedures which leads to optimal placement of dampers has received less attention. Therefore, the current research on optimum design of dampers was conducted in order to detect the optimal damper placement in the structures which are effective in reducing the seismic responses.
Passive energy dissipating devices, such as linear viscous dampers are easy to be instal in the structures. However, the structure with the supplemental dampers usually belongs to the non-classically damped system. Generally, these systems can be analyzed by direct integration methods like Newmark method, so that the responses of the structures can be obtained. But if the degree-of-freedom of the structures is considerable, the direct integration method is thus time consuming. This study presents current researches on mode superposition methods for the non-classically damped systems. Base on the concept in decoupling the non-classically damped system, the response spectrum methods are developed to implement on the Simple Approach proposed by Leu (2010) and it affects computational efficiency of optimizing placement of dampers.
The illustrative examples show that the search algorithm can not be base on the inter-story drifts when response spectrum analysis methods are implemented on the Simple Approach. Hence, the pseudo strain energy and the roof displacements of the structure are adapte for the optimization strategy. The effectiveness of different optimization strategies are then verified by numerical examples. Numerical results show that all damper designs are truly effective in reducing the dynamic response of the structure. To observe from the application of the articial earthquake synthesized from the design response spectrum, it is efficient by applying response spectrum analysis methods in the relocation process when the pseudo strain energy of the structure is used in the optimization strategy.
Although the computational efficiency of optimizing placement of dampers is improved greatly by using response spectrum analysis methods, the results in the higher story shear frames obtained from conducting the optimization where the sensitivity of pseudo strain energy is used may be not so good that the maximum inter-story drifts would over the limit, thus the optimal strategy lose its effectiveness. To make a suggestion, it can be improved by using other optimization strategies and the search algorithms. Besides, the planar shear building structure frames should be taken into consideration for conducting the further research.
Subjects
非古典阻尼系統
模態疊加法
反應譜分析法
阻尼器最佳化配置
人工合成地震
設計反應譜
Type
thesis
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