Comparative Study Of Passive Optimum Interaction Control For Seismic Response Of Parallel Structures

Only design for strength seems to be insufficient and even difficult to ensure the comfort and safety of the occupants as the buildings suffer a strong earthquake since buildings become taller. The subject of structural control offers opportunities to design new structures and retrofit existing structures by application of various control devices, instead of just increasing the strength of the structures at a greater cost. Compared to the conventional seismic resistant design, this technology has the potential for significantly enhancing the seismic resistant capability, reducing the seismic damage of structures and making the building more comfortable to be lived in.An optimum passive control strategy to reduce the aseismic response of two parallel structures (a primary structure and an auxiliary structure) during earthquake action by utilizing the interaction of the two parallel structures is proposed in this thesis. Each structure is modeled as a single-degree-of-freedom system, which is connected to the other structure through a passive control element. In a simpler form, the strategy of the control approach is to reduce energy associated with vibration from only one system, the primary system. This is done by transferring energy to another system, the auxiliary system, and the passive control element by means of interaction between the two systems. In a more complex form, the control is to minimize the total energy of the combined primary-auxiliary system. The analytical formulas for determining optimum parameters of passive control devices used to link two parallel structures based on the principle of minimizing the averaged vibration energy of either the primary structure or the two parallel structures under a white noise ground excitation are firstly derived, and the influence of the structural parameters (damping ratio, mass ratio and natural frequency) of the system on the passive control effectiveness through three diffent numerical examples is also investigated. Then, in order to demonstrate the effectiveness of these strategies, two kinds of passive control devices including Voiget coupling element and Maxwell model-defined dampers, two optimization criteria and 3 kinds of earthquake named 1940 EI Centro NS, Kobe NS and Tangs ground excitations, are considered. Finally, the numerical results of comparing the control effectiveness of different control devices, ground motions on different types of structures are obtained. Emphasis has been placed on finding a suitable passive control device for effectively controlling the vibration of the system under different circumstances through the numerical comparison. The results demonstrate that the passive devices with optimum parameters derived based on the white noise ground excitation are also beneficial to reduce the responses of the parallel structures under the above-mentioned ground excitations and some suggestions about how to choose the passive control device are given.