Unloading Analysis Of Seismic Structure's Dynamic Response

The problem of unloading in engineering is universal. Unloading concept is often used to do qualitative analysis on some engineering phenomena, such as the part of elastoplastic dynamic system yield derives unloading effects. This paper further sums up the unloading analysis idea and creatively develops it into a quantitative analysis method, to solve the changes of system's motion state under small perturbation. The followings are what have been achieved.The difference type direction integration is used for solving dynamic- equation, its calculation assumption causes a "calculation perturbation" effects to the system. According this, one method is presented in this paper to eliminate the "calculation perturbation" effects of Wilson-θ calculation, which greatly decreases the errors and the overshooting of the calculating result , also improves the stability of the calculating result.An energy equation is supplied to the system in time steps while using Wilson-θmethod to solve the dynamic equation, the calculating imbalance acceleration at discrete-time is also made use of, in according these, one method is presented to made the systematic calculation parameter cooperated (energy method) , which eliminates most errors and decrease the overshooting of results. Besides, by combining the preceding method and the energy method, the other advanced method is presented, and also, better calculation result is obtained. After analyzing the motion process of AVS structure system, a method is presented to analyze AVS structure system's dynamic response, the calculating result much allies with equivalent force method. Some proposals for the proper designing of AVS controller are also put forward. The calculating method for frequency perturbation of AVS structure system is presented and the system's dynamic unloading effects is analyzed in this paper. Some additional explanations are also given to the vibration absorption mechanism of multi-freedom AVS structure system. In this paper, a calculation method is derived on to calculate the excitation effects of elastoplastic system by time varying parameter. Basis of the increment of system's secant stiffness within the time step one energy- equation is set on the system, and the system's dynamic equation at discrete time is revised, the action between system's secant stiffness and motion state is calculated. Both of theoretical meaning and practical value for this method are obvious. According the damaged model of damaged Structure, the dropout function of system's elastic deformation energy is set up, to correspond with the system's damage and degradation effects. Beside, new damaged model and ductility model are posed to estimate the system's damage and deform capacity. Moreover, some pre-phase preparation had done for analyses the whole process of seismic damage of damage system.