Theoretical And Experimental Investigations Of Structure Control Based On Piezoelectric Friction Damper

Normal friction damper is a type of energy dissipation device in civil engineering, and has the good ability of energy dissipation. However, as a passive device, it could not change its performance according to structure purpose, load condition and structure response. Piezoelectric actuator has the ability of negative effect. Although its stroke is small, the actuator could generate large force by limiting its deformation. So, it plays an important role in developing smart friction damper. Combined piezoelectric actuator and friction damper, a novel piezoelectric friction is designed and fabricated. Control strategies are also proposed to adjust the control force of damper. In this dissertation, a systematic study on theory and experiment of structural control system with piezoelectric friction damper was performed, and the primary innovative contents include:(1) A new type of piezoelectric friction damper is proposed, and the mechanical performance of the damper is tested on MTS electro-fluid servo-universal machine. The hysteresis behaviors of the damper under various normal forces and voltages are tested when exposed to displacement excitations of different frequencies and amplitudes. Experimental results indicate that the force generation of the piezoelectric actuator increases as preload grows. The force generation is nearly independent of the preload when the preload is greater than certain value. The load-displacement loops of the damper are stable and independent of the excitation frequency when the damper is only exposed to clamping force. The force generation of the piezoelectric friction damper is stable when applied to the linearly increasing voltage signal.(2) The control strategies based on piezoelectric friction damper are further investigated, and the fuzzy sub-optimal bang-bang control and velocity input Takagi-Sugeno (T-S) fuzzy control are proposed. Numerical simulations indicate that the proposed two kinds of methods of semi-active control strategies can suppress the seismic responses. Fuzzy sub-optimal bang-bang control eliminates the amplified accelerations when applying bang-bang control method. However, the implementation of the method increases cost due to all structural state. The implementation of velocity input T-S fuzzy control needs only velocity response, so the control cost decrease and has a high application value.(3) The vibration control approach of the nonlinear structure using piezoelectric friction damper subjected to seismic excitations is investigated. The equation of motion for nonlinear building structure with continuous Bouc-Wen hysteretic model is presented. The initial control force of the damper is determined by time history analysis under minor earthquakes. The seismic reduction of the nonlinear structure installed with piezoelectric friction damper is implemented. Simulation results indicate that the continuous Bouc-Wen model can be conveniently coupled with the equations that describe the motion of the building structure. This model avoids locating transition points that exit in bi-linear models. The acceleration responses of the nonlinear structure may be amplified due to fixed friction force. The proposed fuzzy semi-active control method can generate control force according to structure response, and is very efficient in reducing structure responses.(4) The vibration control approach to the asymmetric-plan building using semi-active friction dampers subjected to multi-dimensional seismic inputs is investigated. In order to reduce the translational and rotational responses of structure, the piezoelectric friction dampers are located on x and y directions, respectively. The proposed strategy is used here to control irregular structure responses under seismic excitations. Numerical results indicate that the friction dampers that are located on x and y directions are effective in reducing both translational and rotational responses of irregular building, and semi-active control method can acquire better effect.(5) A series of shake table tests are conducted on a two-storey steel structure model controlled with a piezoelectric friction damper. The performance of the designed piezoelectric friction damper and the control strategy are evaluated experimentally. The simulation model including damper and structure has been built based on MTALAB/SIMULIMK software environment and hardware/software resources of dSPACE. Shaking table tests of the structure with piezoelectric friction damper is implemented by rapid control prototyping (RCP) technology. The seismic reductions are compared under different earthquake waves. Experimental results indicate that the designed piezoelectric friction damper is effective in mitigating both passive control and semi-active control, and the semi-active control strategy can achieve better performance as compared to passive state.