| The transmission line is an important part of the national life project,and the transmission tower is the main supporting structure of the line.The safety of the transmission tower is closely related to the national economy and the people’s life.The transmission tower is a wind-sensitive structure.Due to the large windward area,the transmission tower-line system has strong coupling effect under the strong wind,which makes the wind vibration response and stress of the transmission tower more complicated.In this paper,one tower and two-spans system of 220 kV transmission line of Zhanjiang-Chikan A-B line in Guangdong province is taken as the research object.Based on the wind tunnel test of aeroelastic model and the nonlinear dynamic time history analysis of the finite element model,the wind vibration response characteristics of single transmission tower and tower-line system under multiple working cases and the analysis of tower collapse under extreme wind load are carried out.The wind-induced vibration response characteristics of transmission tower-line system under multiple working conditions and collapse of tower under extreme wind load were analyzed.It provides some reference for the structural design of transmission tower and the prevention of its instability The main contents and conclusions of this paper include:(1)According to the aerodynamic similarity theory,the aeroelastic model of the tower-line system is designed and made by using the discrete stiffness method,and the dynamic characteristics of the model are verified.Wind tunnel tests under various conditions are carried out and the failure of the tower-line system under the ultimate wind load is observed.(2)By analyzing the wind-induced vibration response results of the displacement and acceleration of the structure measured in the test.And the variation rule of the acceleration power spectral density of the transmission single tower and tower line system is compared.It is found that the coupling effect of the tower line causes a strong coupling resonance response along the wind direction of the transmission tower at the 90° wind direction angle.It is suggested to strengthen the direction of the transmission tower perpendicular to the line.(3)The finite element non-linear dynamic time history analysis of tower-line system is carried out,and the results of dynamic internal force of conductors/ground wires,insulators and main rod are extracted.The accuracy and precision of the finite element results are analyzed.The failure path and collapse of tower under different wind directions are studied.It is found that the bending elastoplastic instability of the transmission tower is the key factor that causes the collapse of the transmission tower.(4)The influence of local yield state on dynamic characteristics of transmission tower is studied.The relationship between load-dynamic characteristics of the transmission tower under the vertical force and horizontal force is calculated.It is suggested that the instability degree of transmission towers can be monitored according to the dynamic characteristics of transmission towers. |
