| At present, researches on the base-isolated seismic have gone a long way and theories have been put into practice in actual construction projects. But the existing seismic isolation techniques mainly adopt the base isolation, which causes the design and construction of the base difficult to handle. As the isolation layer bears much loads, it gives considerable difficulty in designing some structural sections, like the beams and pillars. These defects result in the limitations of the base isolation in practice.According to absorb and draw on the results of recent researches on Lead Rubber Bearings(LRB) at home and abroad, this paper, in the spirit of spreading the application of LRB technique, especially of meeting the demand for earthquake energy absorption and the reinforcement on the old structures, suggests that the roof of the original main structure should be taken as the seismic isolation layer, on which new parts are added. With the introduction of lead bar-plugged rubber as the seismic layer, the dynamic characteristics of the original main structure are changed. As a result, when an earthquake comes, the main structure will react less violently, for the damping layer will absorb the energy transferred. And in this way, the anti-earthquake capability of the building is strengthened. This paper attempts to formulate reasonable computed model for the adding story and seismic decrease structures and derive dynamic equations. At the same time, according to the hysteretic characteristic of the LRB components, Newmark- β time-history analysis is adopted to analyze and calculate the dynamic response of the structures.While conducting vibration analysis of the main structure, the added parts are seen as an elastic quality system, which is connected to the lower parts through the LRB layer. By comparing the displacement and acceleration of the roof of the main structure, and the shearing force between the lower floors without or with the added...
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