Theory And Experiment Of Semi-Active Structural Control Based On MR Damper

Magnetorheological (MR) damper, due to its mechanical simplicity, rapid response, low power requirement, large and adjustable damping force capacity and robustness, has shown to be one of the most promising realizations of semi-active dampers, and the research on its application to civil structures has been attracted lots of scholastic attention.In this dissertation, a systematic study on the theory and experiment of semi-active structural control based on MR damper was performed, and the primary innovative contents are included,(1) A kind of MR damper, named as MRF-04K damper, using the mixed mode (i.e. the valve mode combined with the shear mode) had been designed and manufactured. The used MR fluid is the type of MRF-04K provided by Chongqing Instrument Materials Research Institute of China and the completed damper is approximately 0.5m long and with a mass of 50kg. To accurately understand the performance of MRF-04K damper, the dynamic characteristics of the damper under sinusoidal excitation with different frequency and different amplitude and different applied current levels were experimentally studied. The maximum force produced by MRF-04K damper at a full magnetic field strength is about 20kN while the maximum power required is less than 50w. Further more, the modified Bouc-Wen model had been proposed according to the test data of the dynamic behavior of MRF-04K damper. Comparison with the data between the experimental and the predicted indicates that the modified Bouc-Wen model can accurate portray the behavior of the MRF-04K damper. (2) The semi-active control systems based on MRF-04K damper were further investigated, and the semi-active control law based on the Instantaneous Optimal Control (IOC), the Classical Linear Optimal Control (COC), and the Linear-Quadratic Gaussian (LQG) (only required the acceleration responses of structure as the feedback) algorithms was proposed. On the basis of predictive control theory, the semi-active multi-step predictive control system with the function of time delay self-compensation based on MR damper was proposed. The numerical analysis results indicate that the MRF-04K damper is a semi-active control device with good performance and the semi-active control systems can take full use of the performance of MR damper to reduce the structural responses effectively. (3) The hybrid control system, consisting of a passive base isolation system combined with a semi-active control system based on MRF-04K damper, was explored. Simulation analysis results indicate that the hybrid control system is able to achieve both low interstory drift and acceleration and, at the same time, limit the base displacement. The security of isolated structure was improved largely. (4) Based on the theory and the simulation analysis above, a series of shaking table tests of the semi-active structural control systems based on MRF-04K damper were carried out. Under three different seismic input, the validity of the semi-active control systems based on three different control algorithms, the Instantaneous Optimal Control (IOC) algorithm, the Classical Optimal Control (COC) algorithm and the Linear Quadratic Gaussian (LQG) control problem, and two passive control situations, in which the applied current was fixed at the minimum value of 0A and the maximum value of 2.0A respectively, was verified. The test results indicate that the control systems based on MRF-04K damper are very effective, and either two passive control situations or the semi-active control systems are all able to significantly reduce the seismic responses of the model structure, while the semi-active control systems can effectively utilize the behavior of MRF-04K damper and achieve a better control effectiveness with less control forces compared with the case of passive 2.0A. Which make the realization of the semi-active control systems based on the MRF-04K damper more simple and provide the reliable test basis for applying the semi-active control systems based on MRF-04K damper to civil structures.