Wind-induced Vibration Response Of Transmission Tower Structure

The transmission tower is a special kind of structure because it contains three features----high,hollow-out and slim tower body.It has been widely applied in civil engineering infrastructures such as electricity transmission,radio and television system,communication and construction projects of large-span bridges.With the growth of demand and progress of technique requirements,the transmission tower has been developed to be much higher,lighter and softer.And the other requirement also means to control its sensitivity to wind load.If the transmission tower is destroyed,the power-supply system will be paralyzed.To be worse,it would cause secondary disasters such as the fire hazard.Then these problems will seriously affect people’s production and life.Therefore,it is very important to study the wind-induced dynamic response of the transmission tower.A cat-shaped transmission tower is analyzed as an example in this dissertation,using SAP2000 software to establish the finite element model of transmission tower structure.The wind load acting on transmission tower are digitally simulated and applied to the finite element model to obtain the structural response in time domain.The main contents are as follows.(1)To analysis the basic characteristics of the wind speed and the wind load simulation method.The realization process of the AR method is also introduced with main contents.Based on the AR method,it is convenient to use MATLAB software to stimulate the whole process of fluctuation wind speed.Then it is important to compare the simulation result with the target wind speed spectrum----Davenport spectrum.Therefore,the result is almost in good agreement and it verifies the correctness of the previous simulation.(2)This dissertation adopts the angle beam element simulation.Then it will use SAP2000 software to establish the finite element model of transmission tower structure.And it also will do modal analysis,and get some dynamic characteristics,such as the mode of vibration and natural frequency.Lastly,it is useful to determine the practicability of the model through the further analysis.To be compared,the first order natural frequency of vibration observed from the analysis of the SAP2000 model is similar to the outcome calculated from the empirical formula.And this resultrepresents that the finite element model can realistically reflect the dynamic characteristics.Thus,the useful analysis verifies the practical of this model.(3)The wind load acting on transmission tower is digitally simulated to the finite element model by nodal force method.And then it will also apply to analyze the wind-induced response in time domain through the Newmark method.By the means of time-procedure analysis,it can obtain the displacement,velocity and acceleration time of transmission tower under four respective wind angle of 0°,45°,60°,90°.The maximum of displacement and the acceleration mean square deviation of acceleration response will be finally compared through selecting some nodes to calculate the different displacements of two directions----X and Y.And further analysis of the displacement average number and acceleration response mean square deviation in two directions all add when the height is increased.And these numbers are obviously increased at the top of the tower.To be more specific,the displacement response reaches the maximum at the wind angle of 60°in X direction.And when it comes to the Y direction,the result has the largest number at the angle of 0°.At the meantime,the acceleration response has the same regular.