Seismic Vulnerability Analysis Of UHV Transmission Tower-line System Considering SSI

As an essential component of power transmission system,UHV transmission lines are important carriers for long-distance transportation of high-load electricity,effectively alleviating regional disparities between power surplus in the western and northern regions and power shortage in the eastern and central regions,providing significant power support for high-quality economic and social development.The distribution range of transmission lines is very extensive,inevitably crossing through high-intensity earthquake areas.Under strong seismic effects,transmission lines are prone to damage or even collapse accidents,which seriously threaten the safety and reliability of cross-regional power transmission.Against the background of ensuring national energy security and stable supply,it is of great significance to conduct research on the seismic performance of transmission tower-line systems to ensure the safe and stable operation of the power system under earthquakes.Currently,seismic research on transmission lines rarely considerd the influence of SSI and ground motion of soil variation on the seismic performance of the transmission tower-line system,resulting in incomplete seismic performance assessments of the transmission tower-line system.Based on this,this paper established a finite element model of the transmission towerline system considering SSI,simulated the acceleration time history of seismic soil changes,and conducted research on the collapse,vulnerability,and earthquake losses of the transmission tower-line system considering SSI under seismic soil changes.The main research contents of this paper were as follows:(1)Finite element models of the transmission tower-line system were established using the finite element software ABAQUS.Solid elements and spring elements were used to simulate SSI.By comparing the dynamic characteristics and seismic response,the validity of using spring elements to simulate SSI was verified.A comparison was made with the transmission tower-line system that did not consider SSI,further clarifying the influence of SSI on the dynamic characteristics of the transmission towerline system.(2)Different seismic acceleration time history curves at pile nodes were generated considering soil variation.Based on the dynamic explicit analysis method and considering the cumulative damage effect of the transmission tower members,the continuous collapse mechanism of the transmission tower-line system was studied under seismic excitations without considering SSI,seismic excitations considering SSI but ignoring ground motion soil variation,and seismic excitations considering both SSI and soil variation.The influence of SSI and ground motion of soil variation on the seismic capacity,distribution of damaged members,and collapse mode of the transmission tower-line system were clarified.(3)Using the incremental dynamic analysis method,the probability seismic demand models of the transmission tower-line system were established under different performance states,including seismic excitations without considering SSI,seismic excitations considering SSI but ignoring ground motion of soil variation,and seismic excitations considering both SSI and ground motion of soil variation.The vulnerability analysis of the transmission tower-line system was conducted,clarifying the influence of SSI and ground motion of soil variation on the exceedance probability and seismic losses under different performance states.