Computation of Rayleigh Damping Coefficients for the Seismic Analysis of a Hydro-Powerhouse

The mass and stiffness of the upper and lower structures of a powerhouse are different. As such, the first two vibration modes mostly indicate the dynamic characteristics of the upper structure, and the precise seismic response of a powerhouse is difficult to obtain on the basis of Rayleigh damping...

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Bibliographic Details
Published in:Shock and vibration 2017-01, Vol.2017 (2017), p.1-11
Main Authors: Song, Zhiqiang, Su, Chenhui
Format: Article
Language:English
Subjects:
Coefficients
Construction
Damping ratio
Dynamic characteristics
Earthquake dampers
Earthquake resistant design
Earthquakes
Hydraulic engineering
Hydroelectric power plants
Least squares method
Mathematical models
Mechanical properties
Methods
Modal choice
Nuclear power plants
Observations
Ratios
Seismic analysis
Seismic engineering
Seismic response
Stiffness
Vibration control
Vibration mode
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Summary:The mass and stiffness of the upper and lower structures of a powerhouse are different. As such, the first two vibration modes mostly indicate the dynamic characteristics of the upper structure, and the precise seismic response of a powerhouse is difficult to obtain on the basis of Rayleigh damping coefficients acquired using the fundamental frequencies of this structure. The damping ratio of each mode is relatively accurate when the least square method is used, but the accuracy of the damping ratios that contribute substantially to seismic responses is hardly ensured. The error of dynamic responses may even be amplified. In this study, modes that greatly influence these responses are found on the basis of mode participation mass, and Rayleigh damping coefficients are obtained. Seismic response distortion attributed to large differences in Rayleigh damping coefficients because of improper modal selection is avoided by using the proposed method, which is also simpler and more accurate than the least square method. Numerical experiments show that the damping matrix determined by using the Rayleigh damping coefficients identified by our method is closer to the actual value and the seismic response of the powerhouse is more reasonable than that revealed through the least square method.
ISSN:1070-9622
1875-9203
DOI:10.1155/2017/2046345