Study On Semi-active Control Of Seismic Response For Bridge Structures

As widespread construction of long-span bridges and extensive application of efficient construction materials, the problems of bridge structure vibration have become increasingly prominent. As communications hinge and the lifeline project, the earthquake resistant design and seismic reliability analysis of bridge structures is become significant. Structural vibration control, as a kind of active strategy, withstanding external power input with the teamwork work of the control system and structure to withstand external power input, can effectively reduce the structural dynamic response. This paper describes the basic principles and design of the fuzzy controller steps; forming a suitablestructure of the magnetic damper fuzzy semi-active control strategy; and how to apply with the fuzzy semi-active control to structures to reduce the response of structures by installing MR damper devices in bridges.Firstly, this paper introduces the seismic damage of bridges, the current situation of bridge design, The main failure types of bridge, the classification of vibration control of structures and engineering in recent years. The further simply introduces the basic principles and engineering applications of semi-active control and fuzzy control.Secondly, on the base of the analysis of MRF's performance, various kinds of static and dynamic model have been studied, and their capability of describing the MR damper's virtual performances have been compared. And according to the Parameters of the 200KN full-scale Magneto-rheological fluid which produced by Lord corporation of USA, the SIMULINK model of the MR damper based on the modified Bouc-Wen model has been constructed and the numerical simulations about the performance of the MRFD under the sine wave loads have been processed.Thirdly, implements fuzzy semi-active control to a three-floor frame states installed with MR dampers according to the basic theory and design program of fuzzy control. The seismic response analysis and compared analysis of the magneto-rheological structure are carried with semi-active bi-state and full-state control strategy, and corresponding conclusions are given.Finally, the semi-active control for seismic responses of a long-span cable-stayed bridge was performed using 200KN full-scale MR damper. According to the internal mechanism of structure motion, builds the fuzzy control rules. And they are applied to fuzzy semi-active control of the bridge structure. Comparing and analyzing the effect to structural seismic response with different input variables. Adjusting control voltage of MR, simulates the earthquake response of passive control, semi-active control. The analysis shows that this type of control is capable of reducing the structural vibration efficiently than the passive control.Fuzzy control doesn't depend on accurate model and its operation is easy, it can control MR damper effectively, decrease displacement and velocity. It supplies theory criteria for engineering practice, but also is a good reference for other methods.