| Time-varying strong typhoons such as downburst and typhoon have a great impact on the service safety of transmission towers.The time-varying strong wind field is significantly different from the near-ground wind field in the atmospheric boundary layer.Its particularity results in different response characteristics and failure modes of transmission tower structure from the normal damage.By studying the response characteristics and catastrophic mechanism of transmission towers under time-varying strong wind,we can understand the causes of structural damage and develop relevant performance evaluation methods to evaluate the wind resistance and potential threats of transmission lines in advance.Relevant work has important scientific value and engineering value.The purpose of this study is to systematically study the catastrophic behavior of transmission lines under strong dynamic loads and summarize the dynamic response characteristics and laws of transmission tower-line system under strong wind.A response analysis method considering the dynamic coupling effect of tower-line system is proposed to explore the causes of structural damage of transmission tower under time-varying strong wind.It mainly includes the following parts:In this paper,the time-varying wind load model of downburst is studied,and the existing downburst wind load model is introduced.Based on the improved OBV model,a time-varying wind load model for downburst of transmission tower-line system is established.Taking a practical transmission tower-line system as an engineering background,this paper studies the collapse mechanism of transmission tower-line system under downburst current.The wind-induced response law of transmission tower-line system under downburst load is analyzed.The collapse failure analysis method of transmission tower-line system under downburst load is established,and the dynamic catastrophe mechanism of transmission tower under downburst load is developed.This paper presents a performance evaluation method for high-rise transmission tower-line system under strong typhoon.The cause of wind-induced damage of transmission tower-line system under strong typhoon is studied,and the method of collapse analysis of transmission tower-line system under time-varying strong typhoon is established.Based on the theory of complete aeroelastic model design for transmission tower-line system,the complete aeroelastic model of one tower and two lines is designed and fabricated according to a certain scale.The accelerometer is used to measure the dynamic characteristics of the model,and the stochastic subspace method is used to identify the modal parameters of the aeroelastic model.Wind tunnel tests of large scale aeroelastic model of transmission tower-line system were carried out,and the response of transmission tower was obtained under different wind speeds and wind direction angles.Based on the destructive experiments,the failure morphology characteristics of the transmission tower aeroelastic model are obtained.The experimental results are compared with the theoretical analysis results,which verifies the correctness and effectiveness of the theoretical method. |
