Semi-active Control Strategy And Its Optimization For The Vibration Mitigation Of The Building Structure With MR Damper

How to improve the resistance to the dynamic disturbances such as earthquakes and strong winds for building structures to ensure the personal and property safety is one of the research hot spots in the field of civil engineering.The MR damper is a kind of intelligent semi-active damping device which has a broad application prospect.However,the MR damper-based vibration control needs to be further studied.Firstly,due to the complex and strong nonlinearity of the MR damper,developing its inverse model which can accurately predict command signal is very difficult.Secondly,MR damper-based semi-active control algorithms still need to be the further studied in terms of control effect,and the effect of time-delay and structural parameter uncertainty.Thirdly,all of the the present studies on the connection control of adjacent structures with the MR damper adopt the rigid foundation hypothesis.Therefore,in this dissertation,to mitigate the seismic vibration of building structures,the semi-active control strategies based on MR damper are further investigated.The main contributions of this dissertation are as follows:1.To overcome the difficulty of developing an accurate inverse dynamic model of the MR damper,genetic algorithm and shuffled frog-leaping algorithm(SFLA)are introduced respectively to modify the adaptive-network-based fuzzy inference system(ANFIS),and the modified ANFIS is used to build the MR damper inverse model.Numerical analysis results show that the modified ANFIS strategies perform significantly better than the standard ANFIS in terms of the modelling accuracy and generalization capability.Among these three models,the SFLA-based ANFIS inverse model has the highest command signal prediction accuracy and damping force prediction accuracy.On the other hand,the dynamic characteristics of the MR damper are tested.Based on the test data,a Bouc-Wen forward model is developed,and the effectiveness of the forward model is verified.2.Considering that fuzzy control can directly calculate the MR damper control signal from the structural responses,and yet the parameters of the control system are difficult to choose and the controller optimization is incomplete,a modified SFLA-based semi-active fuzzy control for the building structure is proposed.In this method,the coding strategy of SFLA is modified,so as to achieve the complete optimization of the key modules of the fuzzy control system.The simulation analysis results show that the proposed control method has better control performance than several other control methods,and can still effectively suppress vibration even when the structural parameters vary.3.To meet the requirement of the MR damper-based semi-active vibration control of the building structure with consideration of time-delay effect,a semi-active linear optimal prediction control strategy(GP-ICA-LQG-COC)is proposed which integrates the grey prediction system into ICA-LQG-COC.In this control strategy,considering that LQR is easily combined with grey prediction system but two issues exist in this control system including weighing matrix determination and full-state feedback,a semi-active control,called ICA-LQG-COC,which combines imperialist competitive algorithm,LQG and clipped optimal control is presented.Numerical analysis results show that in the ideal system,ICA-LQG-COC outperforms LQG-COC and two passive control methods.Besides,in the time-delay system,GP-ICA-LQG-COC can effectively achieve the time-delay compensation in the internal system through prediction mechanism.4.To ensure the structural vibration control effect with MR damper and the robustness of the control algorithm,a semi-active robust control strategy considering the design of the mixed sensitivity is proposed.In the control strategy,in view of the conservation and inflexibility in the design of the H∞ control of structural vibration with MR damper,the design of H∞ control system is converted into the optimization design of mixed sensitivity with multi-objective function with constraints,and an output feedback mixed-sensitivity H∞ control is proposed.On this basis,the modified ANFIS technology for building an inverse model is introduced so as to improve the control effect.Numerical analysis results verify the effectiveness of the semi-active control.In addition,the three semi-active control strategies proposed in the dissertation are compared in terms of control effect,the ability to solve the time-delay problem and the ability to deal with the uncertainty of the structural parameters,and the comparison results show that every control strategy has its own characteristic.5.As for the adjacent building structures considering soil-structure interaction(SSI),a control strategy using the MR damper as the connection device is proposed.Besides,to optimize the MR damper positions,a modified GA which can solve nonlinear integer optimization problem with constraints is presented.The numerical analysis results show that SSI has certain effect on the vibration characteristics of the structures and the seismic responses.Especially when the high-rise structure built on the soft foundation is controlled,the SSI effect should be considered.Through connecting the adjacent structures with MR dampers,not only the seismic responses but also the minimum anti-collision spacing can be effectively reduced.In addition,after optimizing the positions of the MR dampers with the modified GA,the vibration and collision problem of the structures can be ameliorated.