Author : Sanat Marathe 1
Date of Publication :22nd March 2017
Abstract: Tuned mass dampers (TMDs) placed in sky scrapers show huge deflections and accelerations as they absorb a lot of the energy from the main structure. The responses of these TMDs need to be controlled with some additional dampers to keep their motion in check. The current paper deals with the numerical study of a similar system in which a TMD (secondary TMD) is used to control another TMD (primary TMD). Primary TMD is also analogous to an important equipment such as a server placed in a building which needs to be controlled. In the present study, the response of a 76-storey Benchmark building is investigated under across-wind loads. Dynamic Time History Analysis of the building is performed in MATLAB 2010a using the wind time history data by state space method. In addition to deflections, drift and acceleration responses have also been taken into consideration. Results show that for an optimum mass of primary TMD (0.33%), the overall response (i.e. peak, Root Mean Square (RMS) and average displacement, acceleration and drift) of the structure is reduced up to 56%. Moreover when secondary TMD is placed, for an optimum mass ratio (2%), the overall response reduction of the structure remains same (i.e. 56 %); whereas the overall response of the primary TMD reduces by 36%. With further increase in the mass of secondary TMD, a trend is observed where overall response of primary TMD goes on decreasing whereas that of the structure increases. Thus, a secondary TMD can be used effectively only up to a mass ratio of 2% of primary TMD. If mass ratio of secondary TMD is kept equal to or below 0.4%, more response reduction for primary structure can be achieved
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