Investigation On Control For Wind Responses Of TV Tower With MR Dampers

Hefei Jade TV tower, the highest steel tower being erected in China, vibrates excessively under intensive wind. The project is used in this paper as engineering background to study the application of passive and intelligent semi-active MR dampers in wind-induced control of high-rise TV tower.A three-dimensional finite element static model of Hefei TV tower is first constructed by using link elements. On the base of it, a two-dimensional lumped mass dynamic model is then reduced from the three-dimensional model when incorporating several assumptions. Along-wind loading is digitally simulated with the aid of random vibration theory and used as load input of dynamic analysis of wind-excited tower.The properties of the MR smart materials and the MR dampers are all introduced in the paper. Then, some kinds of main mechanical models of MR damper are presented particularly and the analysis and comparison of their characteristic are executed. Simultaneously, the revised Bingham model of MR damper is introduced detailedly in line with the experiment results.The wind-induced control of high-rise TV tower using passive and intelligent semi-active MR dampers is studied mainly in this paper. With regard to semi-active control algorithm, a LQR semi-active method, which is based upon classical LQR theory, is put forward in seismie vibration control of Hefei TV tower. A fuzzy semi-active control algorithm, which uses the feedback of damper motion status, is also presented in wind-induced vibration control of Hefei TV tower. The two methods are used respectively and detailed parameter studies are taken in the last method. Then, the analysis and comparison of their results and feasibility are executed. The results indicate that intelligent dampers using the two algorithms can effectively reduce the wind responses, and the control effects aren't sensitiveto external load intensity. The parameter analysis shows that the factors of semi-active control algorithm have great influence on control effect. Obviously, the reasonable parameters are necessary for excellent control effects.Magnetic hysteresis is the intrinsic characteristic of MR dampers, which will have more serious effect on the performance of MR dampers. The analysis of the emulator show that the hysteresis will lead to the adverse results of the semi-active control and the influence will increase with the hysteretic time. The simulation results also indicate that the neural network predictive can effectively solve the problem induced by hysteresis.