隔震结构不同阻尼比地震影响系数曲线的改进研究

Research on seismic influence coefficient of seismic isolated structure with different damping ratio

对我国现行建筑抗震设计规范中不同阻尼比隔震结构的地震影响系数曲线进行了研究。对于隔震结构的计算分析,规范建议采用时程分析方法进行求解;在特定情况下,也可根据规范中不同阻尼比结构的地震影响系数曲线,采用简化的等效线性化方法进行迭代求解。建立了一个典型的采用叠层橡胶支座隔震的12层钢筋混凝土结构;分别采用等效线性化方法和时程分析方法,对隔震层位移、基底剪力等进行分析和比较。发现等效线性化方法的隔震分析结果相对于时程分析方法严重偏大,说明当结构阻尼比大于0.05时,我国规范的阻尼调整系数值过于保守。在此基础上,对规范中地震影响系数曲线采用的阻尼调整和形状参数提出了改进建议。在不同的场地类别和地震分组情况下,改进后的等效线性化方法的计算精度均得到了很大提高,可以准确计算隔震结构的基本动力响应。

The seismic influence coefficient curve of seismic isolated structure with different damping ratio, which was recommended in the Chinese code for seismic design buildings, was studied. In Chinese code, time-history analysis method is recommended for seismic isolated structure, while a simplified iteration procedure based on equivalent linear analysis is also permitted under limited conditions by using a response reduction factor to account for the variation of response as a result of damping. Subsequently, a typical 12-story reinforced concrete building isolated with lead-rubber bearings was established, and the displacement and base shear force of the isolation level were analyzed and compared by using the above two methods. The calculated results from the equivalent linear analysis are generally significantly larger than those from time-history analysis; and it can be concluded that, when the damping ratio of building structures is not equal to 0.05, the damping adjustment factor in Chinese code is too conservation. The improvement suggestions of damping adjusting and forming parameters on the seismic influence coefficient curve in Chinese code were proposed. Using the new parameters, the calculation precisions of the equivalent linear analysis can get greatly improved under different site-classes and design earthquake groups, and can be used to accurately analyze the basic dynamic response of seismic isolated building.