| Compared with the traditional seismic structure,the base-isolated structure and the structure with energy dissipation devices can better satisfy the people’s requirements for building safety and comfort.The displacement response of the superstructure can be decreased significantly by the utilization of base isolation system.While the displacement response of the isolation layer,accord ingly,could not be overlooked,which is the concentration of the study.Due to the limited deformation capacity of the rubber isolation bearings,if which were damaged,the superstructure would be seriously destroyed,the isolation layer is the weakness o f the whole base-isolated structure.So it is very important to control the displacement response of the isolation layer,the most effective way to solve which is to add energy dissipation devices in the isolation layer.In order to overcome the drawback to the overlarge mass of Tuned Mass Damper(TMD),which is one of traditional energy dissipation devices,inerter,proposed according to electromechanical analogy theory,has drawn amounts of attention in the field of structural vibration control in recent years,because of its remarkable mass amplification effect.The main research object of the thesis is a kind of tuned damper based on inerter,Tuned Inerter Damper(TID).Firstly,the analytical solution of the dynamic response,such as modal frequencies,modal shapes,damping ratios,participation factors,etc.,of the 2-degree-of-freedom base-isolated system with supplemental inerter was derived.The simplified system with the specific parameters was analyzed,and it was found that the inerter could decre ase the displacement responses of the isolation layer.However,except for the reductions of the displacement responses of the isolation layer,the acceleration response of the superstructure increased greatly.To address the problem,TID was obtained by combining the inerter with damping element and stiffness element,and was attached to the base-isolated structure.Since the base-isolated structure could control the displacement response of the superstructure effectively,only the displacement response of the isolation layer and the acceleration response of the superstructure need to be optimized.Due to the difficulty of multi-objective optimization,a constrained single-objective optimization method,the optimization method based on the performance requirement,was utilized in the study.The horizontal displacement of the isolation layer determined in advance according to the performance requirement was taken as the constraint condition,and the absolute acceleration response of the superstructure was optimized as the objective.Finally,it was found that TID could control the acceleration response of the superstructure and the displacement response of the isolation layer simultaneously.In addition,due to the fact that the base isolation system is almost always nonlinear,which would cause the great equivalent damping ratio under the small displacement of isolation layer and have a major imapct on the response of superstructure,it is necessary to carry out the optimization design under the design-based earthquake(DBE)and the maximum considered earthquake(MCE).The nonlinear multi-level objective optimization design was carried out for the base-isolated structure with supplemental TID,which concurrently considered the displacement response of the isola tion layer under MC E and the acceleration response of the superstructure under DBE. |
