Reseach On Vibration Control Simulation Of Cable-Stayed Bridge Under Semimic Excitations

Although the Cable-stayed Bridge has been widely applied because of its good performance of mechanics and economy, the research on its seismic resistant behavior is still a problem. The happening of earthquake is uncertain, so traditional earthquake-resistant technology that is to enhance the supporting forces of the structure often cause the structure unsafe and uneconomical. And then many researchers are attracted by structural vibration control that has many advantages to resist seismic action. But on the other hand, the control of flexible bridge structures has not been studied to the extent as building shade, because bridges are so different in geometric form, constructing method, dynamic behavior and operating demands to buildings. It is clearly that little expertise has been accumulated. In this paper, the active algorithm of Linear Quadratic Gaussion(LQG) and the semi-active variable damper algorithm are applied in simulation testing to control the vibration of cable-stayed bridge under seismic excitations. The solution to this problem is of great significance for both theory and practice.At first, an overview to the current development of earthquake-resistant research of cable-stayed, the current development of structural vibration control theory and their application in bridge engineering is given in this paper. And then based on the vibration control theory, numerical simulation model is founded by taking American Bill Emerson Memorial Bridge as prototype. Then the active algorithm of Linear Quadratic Gaussion(LQG) and the semi-active variable damper algorithm are utilized respectively in the simulation model to control the vibration of cable-stayed bridge under seismic excitations,. At last, the outcome of these simulation testing is analyzed to find which strategy is the best.The main research work is as follows:1. Based on detailed drawing of the Cape Gir Bridge, a three-dimensional evaluation model has been developed to represent the complex behavior of the full scale bridge, the linear evaluation model is developed using the equations of motion generated around the deformed equilibrium position.2. After giving the active algorithm of Linear Quadratic Gaussion(LQG) and the semi-active variable damper algorithm, through the software SIMULINK, the simulation testing model is created respectively.3. Evaluation criteria are present for evaluation effect of various strategies that are consistent with the goals of seismic response control of a cable-stayed bridge. And then the outcome of simulation testing is analyzed by comparing the evaluations.4. Active control, semi-active control including simple Bang-Bang, optimal Bang-Bang and HARVOT, and passive-on and passive-off control strategy are verified numerically and compared with each other.The analytical results show that all the designed strategies can effectively reduce the tower's base force and the cable tension's range, and has little effect on reduce the tower's deck force and deck's displacement. Additionally, the s has many advantages over other control systems such as system stability, power capability, work compatibility, etc. It is obvious the semi-active variable damper have a brilliant future.