| As a national lifeline support,transmission lines play an extremely important role in the production and construction of the national economy and normal operation of the daily life of the common persons.The transmission tower is one of the important components of a high-load electrical energy transmission carrier in transmission lines.The safety and stability of transmission tower is especially important in the transmission lines where the structure of UHV grid is the main body.However,for the high-rise structure of the transmission tower,large structural internal forces tend to be generated under the action of natural disasters such as earthquakes,which would lead to the structural damage and other accidents such as disconnection of barrows and collapse,etc.To further improve the transmission tower’s resistance to natural disasters,it is necessary to carefully control the performance of the transmission line tower under the action of large earthquakes and understand the improvement effect when the energy dissipation and shock absorption technology is applied to transmission tower structure.It makes great difference to the improvement of the transmission tower’s mechanical performance and the disaster-tolerant capacity so as to ensure their safe and reliable operation.Main tasks of the paper are listed as followings:The reaction of the transmission tower under earthquake action will be affected by its self-vibration characteristics.The analysis of the dynamic characteristics of the transmission tower is the basis for mastering the self-vibration characteristics of the tower structure and the dynamic time history analysis.In this paper,a common linear tower/drum tower is taken as the research object,and a three-dimensional simulation model of the transmission tower is established.The dynamic characteristics of the transmission tower structure are calculated and analyzed,including the natural vibration period and frequency,the circumference ratio,the vibration mode the damping ratio and the effective mass of the tower structure,etc.According to the model,the joint connection of the rod members of the tower structure,the size of the rod,and the rationality of calculating the lateral stiffness and torsional stiffness of the model are further judged.Based on the time-history analysis of the selection of seismic waves,the determination of seismic level and the amplitude modulation,the seismic response of the transmission tower(original structure)under strong earthquakes is carried out from the transmission tower structure level.The analysis includes the maximum layer relative displacement of the transmission tower under the action of seismic waves,the maximum layer relative velocity,the maximum layer absolute acceleration,the maximum interlayer deformation,the maximum layer shear force,the maximum layer shear coefficient,the maximum overlying bending moment,Maximum interlayer deformation angle,energy analysis,axial force-deformation,plasticity and cumulative plastic deformation ratio of the maximum yielding member.It is found that it is difficult to meet the loss and damage of the tower structure under the large earthquake from the design of the tower structure.It is recommended to pay attention to the cumulative plasticity of the structural members of the tower to determine the loss of the earthquake disaster in detail.To further improve the ability of transmission line towers to resist natural disasters and the structural damage,based on the introduction of typical dampers using energy dissipation technology.The seismic response to the earthquake,when the typical dampers are assembled to the axial and tower tops of the transmission tower,is calculated and analyzed,and the damping control effects of different types of dampers are compared with the original structure of the transmission tower.The results show that the transmission towers with different types of dampers have some differences in resisting earthquakes,but they all have better damping effects,which can provide an important reference for engineering practice.The research results can provide an important reference for mastering the yielding results of transmission tower components under strong earthquakes,optimizing tower structure design,and improving seismic disaster tolerance. |
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