Researches Of Control Method Of Towers And Girders Of The Cable-stayed Bridge Based On Hybrid System Theory

ABSTRACT:It is a flexible structure for the cable-stayed bridge. Its dynamic response under wind or sesmic excitation has important impacts on the structure safety, and corresponding control measures will be taken usually. At present, there have been many theoretical researches and engineering applications of the control problem for major bridges, but it lacks further studies of the collaborative prevention of multi-hazard. This topic is from the major science and technology project "Disaster prevention and mitigation and the safety control technology of major bridges" of transportation construction in2011. As a new theoretical exploration, the subject "Theoretical research of the disaster prevention and mitigation based on hybrid system theory of the major bridges" trys to apply hybrid system theory to the control of bridge systems, which aims at providing a new theoretical analysis of disasters and optimization technologies of control for the bridges having been built and will be built. This paper takes components of the cable-stayed bridge-the bridge tower and girder as the main study objects, which explores the application of hybrid system theory in order to lay a foundation for further studies of the hybrid control of bridge systems.First, the paper reviewed theory and application status of the structural vibration control and hybrid systems and introduced the mixed logical dynamical model. Based on the results, the hybrid characteristics of the structures and the applicability of hybrid system theory were discussed.Secondly, the article studied the control method of wind-induced vibration of the tower of a cable-stayed bridge under construction state with the MLD model. The model of bridge tower was firstly built and the analysis of its vibration characteristics and associated dynamic responses were conducted, and then the design of control scheme was accomplished. Based on the results metioned above and according to the MLD model, the paper conducted derivation of MLD model of the system. Numerical simulations were finally conducted applying the MATLAB to analyze the damping effect of the bridge tower and comparations were made to compare the damping effect of hybrid control and traditional control.Thirdly, the paper studied control methods of the seismic-induced vibration of the bridge tower and girders of an existed cable-stayed bridge with the theory of MLD model. The model of a cable-stayed bridge was firstly built and the analysis of its vibration characteristics was conducted, and then corresponding dynamic response analysises were respectively conducted to the tower and girders. Based on the results above, the paper accomplished the design of control scheme and conducted derivation of MLD model of the system. Then, numerical simulations were conducted applying the MATLAB to analyze the damping effect and comparations were made to compare the damping effect of hybrid control and traditional control.Finally, by comparing the analysis results, the paper got the conclusions. MLD has a certain damping effect on the control of wind-induced vibration of the bridge tower of cable-stayed bridges under construction state and the seismic-induced vibration of the bridge tower and girders of a cable-stayed bridge having been built, and the effect is relatively good which is between the damping effects of traditional active control and passive control. The research results verified validity and applicability of the application of hybrid system theory laying a foundation for further researches.