New Dynamic Participation Factor for Turbine-Generator Foundations
Publication: Practice Periodical on Structural Design and Construction
Volume 15, Issue 1
Abstract
This paper proposes a new dynamic participation factor (DPF) for analysis and design of structures supporting rotational machines, especially large turbine generators. The new DPF takes into account the distribution patterns of the machine unbalanced forces and addresses the phase lags among the forces at different bearings and between the different force components. An example of a real turbine-generator foundation is presented and the new and traditional DPFs are compared along with examination of the vibration modes. The results show that the new DPF can clearly identify the local vibration modes that cause severe resonance. Using the traditional DPF could cause engineers to ignore these modes and, consequently, result in unsafe design. The common misconceptions of dominant fundamental modes and low tuning are clarified. Harmonic analyses (frequency sweeps) are also performed and the results are compared with the results of the new DPF analyses. The new DPF analysis has clear advantages over the harmonic analysis in that it provides a complete picture of the dynamic behavior of the whole structure and does not need the engineer to anticipate the local vibration points. The new DPF analysis can also be used to guide the selection of locations for vibration amplitude check and provides an alternative method to consider the different phasing of bearing loadings, which produces responses to real loading cases.
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Acknowledgments
This study originated from the writer’s work at Bechtel Power Corporation. The writer thanks her colleagues, Jack Demitz, Farhad Farzam, Hongchun Liu, Luis Moreschi, and Janine Smith, for their help with her work on analysis and design of large turbine generator foundations. The constructive suggestions and encouragements from Professors T. T. Soong, Y. K. Wen, J. Shen, and D. A. Foutch are also sincerely acknowledged.
References
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© 2010 ASCE.
History
Received: Feb 25, 2009
Accepted: May 22, 2009
Published online: May 23, 2009
Published in print: Feb 2010
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