| Experimental Study on the Effects of Tuned Mass Damper |
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Experimental Study On The Effects OF TMD On Structure Vibration Reduction
M H Pashaei(1), H Sheydaie (2) I Khatami (3) M jazayeri (4)
School of Engineering, University of Mazandaran, P O Box: 484, Babol, Iran Email: (1) , (2)< mn_khatami@yahoo.com >(3) , < mitrajazayeri62@yahoo.com >(4)
___________________________________________________________________________Abstract Damping is a phenomenon which exists in every system. Some systems have little and some have more. it is related to what elements and how they are assembled with each other in system .such phenomena dissipate energy and reduce the vibrating caused by external applied forces to system like earth quick, wind ,sea wave and thunder .Different types of dampers have been known regarding to their function: passive, active and semi-active. In the field of passive dampers we have many types: tuned mass damper TMD, tuned liquid damper TLD, friction dampers FD and viscose dampers VD. The present research experimentally studies damping ratio of a three-storey building using TMD and without TMD damper to see how damper increase the damping ratio . To carry out this study A structure and the necessary equipment including a loading system and a data acquisition system are used.. Structure examined under the free vibration in this way: A small displacement implemented to the structure as a free vibrations. And by carrying out more than 150 tests, the damping ratios of the structure using TMD and without TMD in different loading conditions are obtained. The results show that the Tuned mass damper has a major effect on the damping characteristics of the structure The results also show that the increasing the loading applied to structure doesn’t change the damping ratio which is analyses an Ansys software . Key Word: damping ,tuned mass damper ,damping ratio ___________________________________________________________________________ 1 Introduction
1.1 Damping concept Damping is a phenomenon where the amplitude of vibration in a mechanical system steadily diminishes. The effect of damping is to remove energy from the system. Energy in a vibrating system can be dissipated, being converted into heat [1,2,3].
Damping is present in all vibrating systems. Every system which possesses mass and elasticity is capable of vibration. Dampers are kind of device in order to dissipate vibration forces... Different types of dampers have been known .in general they are divided in three categories: passive, active and semi-active.[4,5,6,7].Tuned liquid dampers[8] and Tuned mass dampers[9] are very usual one which are using nowadays in many structural system and the second one is our research topic.
2 Examined model
In present research A structure is being designed and built as a model of a real structure in Fig.1
Fig 1: drawing and picture of model
the weight of the structure is 200 kg and the stiffness of that is k=6.666 N/mm and the natural frequency is w=0.056 Hz which was analyses in a finite element software Ansys Fig 2: analysed model in software
3 TMD design [11~25]
in order to design the TMD with study of many books and article and the real TMD used in some real structures in the world like Citicope tower in New York [10] we came to this result : the mass of TMD can consider 2 percent of structure’s mass or less, but it should be design in a optimum way . Natural frequency of TMD Should be as the natural frequency of real structure. When the real structure approach to its natural frequency caused by external applied forces, TMD must approach to its natural frequency too. The vibration of TMD at natural frequency causes turbulence in general movement. In this way the frequency of structure go further from its natural frequency. As a result, the stiffness of TMD also should consider 2 percent of structure’s stiffness to . be as the same.
The Mass Of TMD: (1)
The Stiffness Of TMD: (2)
After determination of mass and stiffness’ amount of TMD, a block and spring design and then manufactured at Fig 4 and 5. |
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