Research On Seismic Vibration Of Transmission Tower Based On U-shaped Memory Alloyed Damper

Transmission tower system is one of the most important lifeline systems of a city.However,in the past few decades,it has been found that pylon systems are vulnerable to earthquake damage.Shape memory alloy(SMA)has attracted extensive attention and research in seismic engineering field in recent years due to its excellent ability of deformation recovery and energy dissipation.In order to reduce the impact of earthquake on transmission towers,a tuned mass damper(TMD)made of U type hyperelastic shape memory alloy(SMA)is proposed,and the damping effect of this damper on transmission towers is studied.(1)The performance of a self-reset superelastic SMA U-shaped damper under cyclic load is systematically studied.The mechanical behavior of SMA-UD was studied numerically.By comparing the numerical model with the experimental results,it was found that the model could better simulate the mechanical properties of the damper.Typical hysteresis characteristics,including yield strength,peak force,residual deformation and equivalent viscous damping ratio,in seismic applications under different loading amplitudes are studied numerically.The simulation results show that the damper exhibits good and stable flag hysteresis curve and good bending capacity in multiple loading cycles,and also shows ideal self-reset behavior under large displacement amplitude,which can minimize the residual deformation after strong earthquake.Compared with the traditional SMA damper,the damper can reduce the residual deformation after strong earthquake.SMA-UD provides a more attractive solution for seismic design in the future.(2)Taking a 220 k V transmission tower in Northeast China as an engineering example,the precise model of the transmission tower is established in the three-dimensional finite element software ABAQUS.The dynamic characteristics of the transmission tower structure are analyzed,and the natural frequency and modal array of the obtained transmission tower are analyzed.Then,four kinds of seismic waves are selected,and nonlinear dynamic time-history analysis method is adopted to study the seismic response characteristics of transmission tower model under different seismic waves.The performance indexes include peak displacement of tower top,peak acceleration and reaction force of transmission tower base support,and the response curve of transmission tower at any time under earthquake action is obtained.(3)An appropriate damper is selected by adjusting the damper parameters,and the damper’s control effect on transmission tower vibration under four different seismic excitations is simulated and studied in the finite element software.The analysis results show that it is feasible to adopt the tuned mass damper to control the transmission tower structure vibration.According to the layout principle of the damper,the number and position of the damper are adjusted,and three different damper installation schemes are designed.The seismic time-history response of the transmission tower under the three different schemes is analyzed,and the optimal location of the damper is determined at the top part of the tower with the largest displacement.