Passive Control of Wind-induced Vibration of Tall Buildings Using Combination of Controlled Mega-Sub and Secondary Skin Systems

Khodaie, Nahmat (2018) Passive Control of Wind-induced Vibration of Tall Buildings Using Combination of Controlled Mega-Sub and Secondary Skin Systems. Doctoral thesis, University of Mohaghegh Ardabili.

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Text (کنترل غیرفعال ساختمان‎های بلند در مقابل باد با ترکیب روش‎های مگاساب کنترل‎شده و سیستم رویه ثانویه) Nahmat Khodaie.pdf Download (490kB) | Preview

Abstract

The present study proposes a new structural system to reduce the wind-induced vibrations of super-tall buildings. The proposed structural system is a combination of an exterior tubular structure and an interior or core structure, and consists of two upper and lower parts. At the upper part, the exterior and core structures are isolated from each other. Damping devices are used in this part to limit the relative flexural motion between the exterior and core structures, and control wind-induced motions of the building by dissipating the vibration energy. In order to demonstrate the control effectiveness of the proposed structure, a numerical example of a super-tall building is presented, and the along-wind and crosswind responses are obtained using the frequency domain analysis of multi-degrees-of-freedom lumped mass models. The control performance of the proposed system is compared with that of the structure controlled by the tuned-mass-damper (TMD) system. The results demonstrate that the proposed control structure, which is a self-control system, can effectively reduce the wind-induced vibrations of super-tall buildings and improve occupant comfort during strong wind excitation. Beside this work, in the present study the effect of the number of the isolated substructures on the wind-induced vibration control of the passive controlled mega-sub (PCMS) systems is investigated. According to the numerical investigation on an example super-tall building, up to 90 percent of the control capability of controlled PCMS systems can be achieved by the system having only one isolated substructure. This option of PCMS systems, which shows very high control efficiency compared with the tuned mass damper (TMD) systems, is practically an exceptional option of PCMS systems and can be used as an economical and practical option for the wind-induced vibration control of tall and super-tall buildings. Using this result, another control idea is proposed and evaluated for reducing the wind-induced vibration of tall TV towers. Based on the proposed idea a portion of the structure of the towers at the observation deck is isolated and regarded as a vibration absorber substructure. In order to investigate the effectiveness of the the proposed system, the 310-m tall Nanjing TV tower in China, which has two observation decks at the heights 180 m and 240 m, is studied. The results indicate that the proposed self-control structural system has higher vibration control capacity than the TMD system. In the proposed system, since a part of the main structure performs as a vibration absorber, the limitations of the TMD system are overcome.

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