SHAKING TABLE TEST ON UHV SINGLE CIRCUIT CUP TYPE TRANSMISSION TOWER- LINE COUPLING SYSTEM

Ultra high voltage (UHV) transmission structures have not been subjected to severe natural disasters since their large scale construction in China. In order to analyze the seismic response characteristics of a transmission tower-line coupling system and the dynamic influence on the tower from ground wire and conductors under earthquakes, a shaking table test on a 1000kV UHV transmission tower-line system aiming at proposing a rational suggestion for the aseismic design of a high-voltage tower-line system were carried out. Taking 1000 kV single circuit transmission lines of an ultra high voltage transmission structure as the prototype, a three-tower two-span model was made and the boundary conditions were also simulated. Seismic test were conducted under 8 degree seldom-occurred earthquakes and four types of earthquake ground motions were selected as the seismic excitations. By test results, it was found that the conductors have a greater impact on the natural vibration frequencies of a transmission tower in the cross-line direction compared with the case for the along-line direction. For the tower with conductors, the vibration energy on the tower top in the cross-line direction exhibited the shifting to a low-frequency, comparing with the corresponding standalone tower. In general, the values of the dynamic response for the transmission tower with conductors decreased by 4%-45%, compared with the standalone one. It shows that the existence of conductors improves the aseismic capacity of the transmission tower. Thusly, it is necessary to consider the influence of conductors in the dynamic analysis for the transmission tower to avoid the overestimation of seismic responses.