Seismic performance assessment of a 550 kV GIS porcelain insulated bushing: shaking table test and numerical simulation

Porcelain bushings in gas-insulated switchgear (GIS) substations are critical yet seismically vulnerable, owing to their slender geometry, large mass, and brittle material. This study presents a comprehensive seismic evaluation of a 550 kV GIS porcelain insulated bushing through shaking table tests and refined finite element analysis. Shaking table tests were conducted at three seismic intensities 0.15 g, 0.40 g, and 0.50 g (0.546 g actual) PGA, with full experimental details reported for the specimen, loading protocol, and instrumentation. A beam and shell finite element model was developed and validated against the test data. Test results show a maximum base stress of 9.12 MPa at 0.50 g far below the porcelain’s ultimate strength of 25 MPa and white-noise scans confirm that no structural damage occurred. A peak acceleration amplification factor of 6.94 at the bushing top highlights significant dynamic amplification through the structure. The FE model shows excellent agreement with the test results: the first-order frequency is nearly identical, the second-order frequency error is under 10%, and the maximum stress deviation is only 4.3%. These findings confirm the bushing’s seismic integrity under strong shaking and demonstrate that the validated FE model is a cost-effective tool for seismic assessment when experimental testing is impractical.