Research On Aero-elastic Model Of Lattice Tower Based On Wind Tunnel Test

Along with the rapid developments of modern science technique and economic construction, more and more high-rise lattice towers are widely used, such as television towers, power transmission towers and microwave communication towers. These structures play a much important part in people's daily life. Because of their characteristics of highness and flexibility, wind induced their responses, especially dynamic responses are quite notable and make people give a serious consideration on this problem. To seize wind induced dynamic responses of lattice structures, there is still much investigation to be carried out. Aerodynamic damping of lattice towers plays an important role in wind-induced dynamic response, but research on this problem is very limited. This paper focuses on wind-induced dynamic response and aerodynamic damping of lattice towers, and the main work is as followings.1. Wind tunnel tests of the lattice towers' aero-elastic models are introduced in detail, which include simulation of the wind field, manufacture of the model and method of the experiments. The author processed the experimental data, analyzed the action mechanism of the apex acceleration response, calculated the RMS of the apex acceleration response in along wind direction, and analyzed the rules by which the RMS responses varied with the wind velocity and wind directional angels.2. Determination of aerodynamic damping of lattice towers. Various methods for determination of aerodynamic damping are available. At the present time, the empirical mode decomposition (EMD) method is thought to be the most suitable method to extract data array trends or mean value, which can treat nonlinear problems objectively. According to the experimental results, the rules that the aerodynamic damping varied with the wind velocity are analyzed with the combined use of the empirical mode decomposition (EMD) method, the random decrement technique (RDT) and the Hilbert transform (HT).3. Using the frequency domain analysis method of the random vibration theory, the author analyzed the dynamic response of the two aero-elastic models respectively, calculated the RMS of the along-wind accelerations and displacements under different wind velocity, conducted comparisons between the experimental results of the wind tunnel tests and two kinds of calculated results, those only structural damping is considered and those aerodynamic damping is also included.