Research On The Seismic Effect Of The Transmission Tower-line System Under The Multi-dimensional Earthquake

Transmission tower-line system occupies an important position in economic development,the phenomenon of the transmission tower collapse and transmission line damage have occurred in a large number of earthquakes.A large number of earthquake damage show that,for the transmission towers such high-rise structure,the earthquake will lead to its significant dynamic response,and the influence of the ground motion tilt component and the vertical component cannot be neglected.However,due to the lack of recorded data of the tilt component,the research on the seismic effect of the transmission tower-line system under the multi-dimensional earthquake is limited,and the only research is mainly on the influence of the tilt acceleration,the influence of tilt angular displacement and vertical acceleration are poorly understood in earthquake engineering without in-depth research.Thus,this paper make a research on the methods of obtaining the ground motion tilt components and the dynamic response of the transmission tower-line system under the multi-dimensional earthquake including the tilt component.The main research contents and the corresponding conclusions are as follows:(1)The research on two methods,the methods of elastic wave theory and frequency-rate,for obtaining the tilt component have been made,then the tilt component in Taiwan Chi-Chi earthquake have been obtained by using these two methods,and the power spectrum of the tilt accelerations obtained have been compared.Through the comparison,it is found that the former has a wider frequency band and the high frequency part is rich,while the latter is mainly concentrated in the low frequency part,and the viewpoint that tilt components obtained by the two methods should been comprehensively considered is put forward.(2)The single tower and tower-line system are simplified,and the motion equation of simplified calculation model under horizontal acceleration,coupled horizontal,tilt acceleration and tilt angular displacement,and coupled horizontal,vertical,tilt acceleration and tilt angular displacement are developed.Then,the dynamic response of the structures are obtained by solving the motion equation.The results are very close to that of the finite element numerical simulation,so the accuracy and rationality of the motion equation are verified.(3)The obtained tilt components are applied to the dynamic time history analysis of the single tower and the tower-line system.It is found that the influence of the tilt component obtained by the method of frequency-rate on the dynamic response of the structures is much greater than that obtained by the method of elastic wave theory.This is due to that characteristics of their power spectrum are different,the characteristic frequency of the tilt component obtained by the method is closer to the frequency of the transmission tower,and the method of elastic wave theory is often underestimated the seismic effect of the structures caused by ground motion tilt components.(4)The ground motion component would cause the dynamic response of the structure increasing,especially when the influence of the ground motion tilt angular displacement is considered,the structure will have an additional P-Δ effect,while the dynamic response of the structure increasing,the displacement response of the tower would also been led to unilateral offset.At the same time,the influence of the ground motion vertical acceleration on the dynamic response of the structure would greatly increase,which should be paid attention to.