With the widespread application of gas-insulated transmission lines (GIL) in ultra-high voltage converter substation

the impact of seismic on its structural safety has been concerned. In this paper

the response characteristics of GIL under seismic action is analyzed on the basis of a refined finite element model

and specific performance enhancement methods for the seismic weak points are proposed. The study shows that the primary weak points of GIL are located at vertical bends

with such two failure modes as damage of enclosur

e strength and of internal pull-out of internal conductor joint. Additionally

the dynamic amplification effect of the supports is significant

the acceleration amplification factors generally exceed 2.0

however

the dynamic amplification effect of the supports is not the sole factor determining the seismic performance of the GIL. By increasing the fundamental frequency of the supports and fixing the connections between the supports and the enclosure

the peak of the relative displacement of the internal conductor and the peak stress of the enclosure can be reduced effectively

thereby significantly improving the overall seismic performance. The reinforcement measures can reduce the seismic vulnerability of the GIL by more than 50% when the peak ground acceleration (

PGA

) exceeds 0.4g. This study in this paper provides theoretical support and practical guidance for improving the seismic performance of GIL.