Study On Rolling Ball Isolated Structure Based On Soil-structure Dynamic Interaction

Base isolation is one of the important protective measures to maintain normalusage function of buildings under earthquake. Most current theories of base isolation arebased on rigid foundation assumption, without considering the influence of soil-structure dynamic interaction on structure. Domestic and foreign scholars have studiedthe issue, but lack comparative analysis on the influence degree of soil-structuredynamic interaction on different isolation structures, and studies of ball isolationstructure based on the soil-structure dynamic interaction is still blank, so this article hasstrong theoretical significance for the research.Based on the finite element software ANSYS and theoretical analysis, the finiteelement analysis models of frame structure and frame-shear wall structure with groovedball isolation device were established in this paper, and then compared the influencedegree of soil-structure dynamic interaction on both isolated structures through timehistory analysis. It mainly completed the following work:1. Introduced the existing ball isolator with spring reduction and grooved ballisolator, then established mechanical model and motion equation of the grooved ballbearing isolation system, considering soil-structure dynamic interaction. Also soilmotion equation was established in three-dimensional time domain by the method oflumped-mass explicit finite element.2. Based on the finite element theory, it considered an8-story reinforced concreteframe structure as a research object. There were five cases:1) no isolation structurewithout considering soil-structure dynamic interaction;2) isolated structure withoutconsidering soil-structure dynamic interaction;3) isolated structure consideringsoil-structure dynamic interaction at site1, site2, site3(soil are softened). The analysismodels were established with direct method and used time history analysis by ANSYS.Through comparing seismic response of the superstructure in all cases, it found that thesofter the site soil was, the bigger the influence of soil-structure dynamic interaction onthe frame structure would be.3. Considered an8-story reinforced concrete frame-shear wall structure with thesame height and span as a research object. Using the same methods, it concluded thatthe softer the site soil was, the bigger the influence of soil-structure dynamic interactionon the frame-shear wall structure would be. 4. Through comparing the influence degree of soil-structure dynamic interaction onseismic response of both isolated structure at three sides, it found that in the same sitecondition, the frame-shear wall isolated structure was more susceptible to soil structuredynamic interaction than the framework isolated structure. The softer the site soil was,the more obvious the influence degree of soil-structure dynamic interaction the formerone would be compared with the latter one, and the influence degree was proportional tothe stiffness of the superstructure and inversely proportional to the stiffness of the sitesoil. Then further pointed out the necessity of considering soil structure dynamicinteraction in structure seismic isolation design.