Theoretical And Experimental Studies On Smart Piezoelectric Friction Dampers

Normal friction damper is a type of passive energy dissipation devices. When the contact force is very large, the damper may not slide under a small or moderate earthquake and therefore dose not dissipate any energy. On the other hand, when the contact force is too small, the damper only dissipates litter energy under a large earthquake due to its small sliding frictional force. However, smart piezoelectric friction damper has the ability to adjust the normal force on the contacting surfaces of the friction damper in real time by utilizing the negative piezoelectric effect. Thereby, the energy dissipation ability of the friction damper can be greatly improved.For proposing a new control strategy and a novel piezoelectric friction damper, the followings are conducted or developed in this dissertation:First of all, the development process of civil structural control using piezoelectric materials is reviewed, which mainly discusses smart piezoelectric actuators and smart piezoelectric energy dissipation devices in details.Second, by comparing the velocity feedback control algorithm with the displacement feedback control algorithm, it is suggested that the controlled structure with variable friction dampers subjected to near-fault earthquake with distinct pulses should be controlled by velocity feedback algorithm.Third, Aim at the shortcomings of suboptimal Bang-Bang control, a kind of continuous function of story velocities such as hyperbolic function is introduced to improve the sub-optimal Bang-Bang control principle and it is developed to a semi-active control strategy for adjusting variable friction dampers. By using the genetic algorithm, the parameters in the controller or in the damper are optimally determined. The influence of the continuous function on control effectiveness is analyzed. By keeping the related parameters fixed, the adaptive ability of the improved controller is compared with other control algorithms presented in this paper as the earthquake intensity is altered.Fourth, the simulation model for the building controlled by semi-active friction dampers subjected to multi-dimensional earthquakes is established and it is further converted to a real time (on-line) model using the real time interfaces in Dspace Control System.Then, a new type of piezoelectric fiiction damper composed by a slotted bolted connection and two tube piezoceramic actuators is designed. By testing, the mathematical expression of the input voltage and the output contact force provided by actuators is obtained.Finally, the relation of the performance based aseismic design and the structural control is discussed preliminarily. The promising prospects of structural control are proposed.