| Firstly the research states of base isolation at home and abroad are introduced in this thesis. Afterward based on earthquake response spectrum, the base-isolated structure is analyzed. Moreover the characters and the design method of the parallel isolation system and sand cushion isolation system are studied. The main contents and results are as follows.1. The research states of parallel isolation system are introduced firstly. Based on the kinematic formula of parallel isolation, the formula of equivalent damp, equivalent period and equivalent stiffness of its isolation layer are given out.2. the formula of the parameter A of parallel isolation system is also given out Based on the speciality of the parallel isolation system, which the transfer force between the rubber bearing and the sliding isolated bearing is considered, the formula of the parameterλis revised. If the parameterλof this system is reasonably designed, the period of the system will be longer than that of the common base isolated structure. The design technique of parallel isolation is given out, which can be used for reference in practical project aftertime.3. The research states of earthquake spectrum at home and abroad are introduced in this thesis. With the object of single mass particle, the common characteristics of statistic of parallel isolation are studied. The displacement and acceleration of earthquake spectrum of parallel isolation are given out. The rule of changes between the parameters and earthquake spectrum are studied.4. Arranged and analyzed a lot of test data of the sand cushion isolation, it is evident that the effect of sand cushion isolation is not only related with the thickness of sand cushion, but also effected by the grain diameters, compactness and gradation of sand cushion. Based on the analysis of test data, the design technique of sand cushion isolation layer are given out. It can be used for reference in practical project aftertime.
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