What is it about?
In this study, an iterative step-by-step procedure is proposed for optimal placement and design of viscoelastic dampers in order to achieve a target damping ratio based on simple equations and quick estimation. Through the procedure, the dampers are placed one by one in stories with maximum inter-story drift at each sequence. Effect of lateral stiffness of added dampers and consequent changes in frequency of the structure, as well as changes in damping characteristic of the structure after adding each damper are also considered at each sequence. In order to achieve an economical design, dampers are designed according to the lateral stiffness at each story of the main structure instead of using identical dampers in all stories. During the whole procedure, a time-history analysis is performed at each sequence. Two numerical examples, including an 8-story and a 15-story building, are presented. The results indicate that optimal arrangement of dampers has a considerable influence on reduction of roof displacement up to 25% compared to uniformly distributed arrangement of dampers. In addition, with optimal arrangement, the number of dampers needed to achieve a specific inter-story drift is significantly reduced, and the structural damping ratio is improved to a target value reflecting global optimality of the proposed method.
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Why is it important?
It is explained how lateral stiffness values of VE dampers are determined through an iterative process and how required area as well as thickness of dampers are consequently calculated based on presented equations. Subsequently in section 4, proposed method is described clearly. It is clarified in this section that how an economical design can be achieved by this procedure. This procedure can therefore lead to reduction in dimensions, and consequently costs, and also the number of required VE dampers. In section 5, two numerical examples are introduced and the analyses will be performed on the represented models using proposed procedure. Then results of the analyses are illustrated in the form of tables and plots and then they are discussed in detail. These results are also verified with results of a 10-story model. Finally, a discussion is carried out on the damping ratio created by different arrangements of dampers.
Perspectives
In this study, in order to achieve optimal design and placement of VE dampers, a sequential procedure is proposed, which is a combination of methods presented by Zhang and Soong [6] and Soong and Dargush [1]. In the proposed procedure, contrary to Zhang and Soong method [6], identical VE dampers are not distributed in all stories, but they are designed in accordance with the lateral stiffness of each story, as proposed by Soong and Dargush [1], and at the same time, through a sequential process these dampers are placed in locations with maximum inter-story drift being more efficient. In fact, through the proposed procedure, characteristics and placement of VE dampers are interactively changed and updated until a general optimal design is achieved. Section 3 is devoted to design procedure of VE dampers.
Seyed Mehdi Zahrai
University of Tehran
Read the Original
This page is a summary of: Iterative step-by-step procedure for optimal placement and design of viscoelastic dampers to improve damping ratio, The Structural Design of Tall and Special Buildings, May 2017, Wiley,
DOI: 10.1002/tal.1361.
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