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Title:	Development of hybrid tuned liquid damping device for vibration mitigation of structures
Authors:	Ali Akbar Pabarja (P62284)
Supervisor:	Mohd. Yazmil Md. Yatim, Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Structural dynamics Damping (Mechanics) Tall buildings -- Design and construction
Issue Date:	27-Mar-2019
Description:	Tall and slender structures have lower damping ratio when compared with other structures. This makes usage of auxiliary damping devices in these structures inevitable in order to mitigate structural vibrations to a safe and imperceptible level. Tuned Liquid Dampers (TLDs) have been widely employed as one of the damping devices in tall and slender structures. However, TLDs provide lower damping ratio when compared with other damping devices like Tuned Mass Dampers (TMDs). In addition, they can be only tuned to one frequency when they are constructed. In this study, a new type of damping device which combines the concept of TLDs and TMDs are introduced and tested. This new damping device is composed of a water tank and a pendulum (i.e. a mass suspended from a pivot) and aims to satisfy two main objectives; first to increase in the energy dissipation of conventional TLDs and second, to allow tuning of conventional TLDs to multiple frequencies without changing the size of their water tank. The first part of this study involved in the experimental tests in which the efficiency of the proposed damping device in reducing structural vibrations was evaluated through a series of free vibration and forced vibration tests. For experimental tests, a three-story one-bay 1/3-scale steel structure was constructed and equipped with accelerometers and LVDTs at each floor. Damping ratios, displacement and acceleration responses of each floor were measured and compared in the experimental tests. Two conventional TLDs together with three samples of the new damping device with single pendulum and a sample of the new damping device with double pendulum were constructed for the experimental tests. The second part of this study involved in the numerical modeling and analysis. It evaluated the efficiency of the new damping device when it was subjected to seismic forces. The results obtained from free vibration tests indicate that the new damping device produces twice more damping ratio at its optimal pendulum mass ratio compared to the conventional TLDs. In addition, under forced vibration tests, the measured peak displacement response at the resonance frequency was reduced 75.9% when the new damping device with single pendulum was installed at third floor. However, reduction in the peak displacement response of the structure was 60.7% when the conventional TLD was mounted at the third floor. The peak acceleration response at the resonance frequency of the steel structure was reduced, 51.8% and 68.2%, respectively, when the conventional TLD and the invented damping device with single pendulum was installed at the third floor. It was also observed that, when the invented damping device was tuned to the first and second natural frequencies (i.e. double pendulum) the peak acceleration and displacement response was reduced at least 15% more than the time when it was tuned only to the first natural frequency of the steel structure. Results of numerical studies also indicated that compared to the conventional TLD acceleration and displacement responses were at least 10% smaller when the new damping device was installed on the structure. Thus, it can be concluded that the new damping device is an efficient tool for vibration mitigation of structures especially when higher mode shapes contribute significantly in the dynamic responses.,Certification of Master's / Doctoral Thesis" is not available
Pages:	193
Call Number:	TA654.P334 2019 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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