NEHRP Clearinghouse
- Title
- Experimental and Analytical Studies of Base Isolation Systems for Seismic Protection of Power Transformers.
- File
- PB2006111702.pdf
- Author(s)
- Murota, N.; Feng, M. Q.; Liu, G. Y.
- Source
- National Science Foundation, Washington, DC., September 30, 2005, 252 p.
- Identifying Number(s)
- MCEER-05-0008
- Abstract
- This report presents a comprehensive study involving tri-axial earthquake simulator testing on seismic isolation of electric power transformers. The lightweight nature and base displacement constraints of power transformers require a different philosophy (from buildings and bridges) in designing a base isolation system. In this study, two isolation systems were developed, one using sliding bearings combined with rubber bearings and the other segmented high-damping rubber bearings. Tri-axial earthquake simulator testing was performed using a large-scale transformer model equipped with real bushings. Important observations were made on the seismic responses of the transformer and its bushing. In particular, the vertical component of the ground motion induced high-frequency response of the bushing when the transformer was isolated with the sliding isolation system. Numerical simulation confirmed that the two isolation systems, even designed with the same force-displacement hysteresis, can perform differently under tri-axial ground motions. This is because the vertical motion changes the friction forces in the sliding bearings that can excite high modes in the transformer-bushing system. Furthermore, the effect of the interaction with the bushing connecting cables on the seismic isolation performance was experimentally evaluated in this study. In conclusion, the base isolation technology, when properly designed, is a highly effective measure for seismic protection of power transformers.
- Keywords
- ; Simulators; Numerical analysis; Electric power; Earthquake engineering; Power transformers; Seismic isolation