New MR Dampers And Semi-active Control System Of Long-span Spatial Structures

Magnetorheological (MR) damper is a semi-active control device, which takes advantage of both the reliability of passive devices and the adaptability of fully active control devices, so it is considered to be one of the most promising devices for mitigation of serious hazards induced by earthquakes, and the corresponding researches have attracted a lot of scholastic attentions. In this thesis, the design method, improved structure, performance test, mechanical model of MR dampers and semi-active control system of long-span spatial structures based on new MR dampers are studied. The primary research work and achievements in this dissertation are included as follows.(1) A simplified design method of share-valve mode MR damper is proposed. In this method, the design process of the MR damper is simplified through the combination of the magnetic circuit design and the structural design as one process based on the principles of magnetic circuit optimization. The results show that the proposed simplified design method is simple, efficient and reliable, and it may become one of the most practicable methods for the engineering design of the share-valve mode MR damper.(2) Tow new MR dampers are designed, produced and tested and a damping force prediction model is proposed. The structure of traditional share-valve mode MR damper is improved and two new MR dampers denoted MR damper with bidirectional adjusting damping force and MR damper with full-length effective damping path respectively are designed and the influence of the structure parameters and the distribution of magnetic field on the mechanic characteristics of the damper is studied by dynamic tests and magnetic field tests in the damping path. A damping force prediction model is proposed based on the results of magnetic finite element simulation and tests. The results show that both dampers are consistent with the design. Medium output powers without current input can be obtained by the proposed MR damper with bidirectional adjusting damping force which can ensure the fail-safe property of the system while the maximum output powers of the proposed MR damper with full-length effective damping path are doubled at least and the dynamic ranges of the output powers are increased by 70% at least compared to MR dampers of traditional structure and same dimension. The proposed model can predict the actual damping force of the MR dampers proposed accurately. (3) Tow new dynamic models of new MR dampers are proposed based on the Logistic function and the Gompertz function and parametric identifications of the models according to the tests results of the new MR dampers proposed are conducted. The results show that both models can identify the dynamic characteristics of MR dampers precisely without complicated function form.(4) A semi-active control system of long-span space structures based on new MR dampers is established. The semi-active control system of long-span space structures is established based the new MR damper with bidirectional adjusting damping force according to an actual indoor gymnasium. A medium bang-bang control algorithm, a hierarchical control algorithm and a revised clipped-optimal control algorithm are proposed based on the three states output power properties of MR damper with bidirectional adjusting damping force and control results of different control algorithms are compared. The results show that the control levels are greatly upgraded by the control algorithms proposed.