隔震结构振型分解反应谱计算方法研究

隔震结构采用分离式计算方法进行结构设计，由于使用统一的减震系数，部分楼层剪力调整偏大。采用振型分解反应谱法，将隔震层和上部结构作为整体结构进行分析可有效解决这一问题。然而隔震层的阻尼与上部结构显著不同，隔震结构是一个不同阻尼的组合体。采用振型分解反应谱法进行结构整体分析时，计算隔震结构的振型阻尼比，是计算地震作用的关键。采用能量法，推导出隔震结构振型阻尼比的计算公式，并对其进行简化。结合GB 50011-2010《建筑结构抗震规范》反应谱，给出了适用于隔震结构整体模型的振型分解反应谱地震作用计算方法。对一栋16层隔震框架结构地震作用分析表明，按振型分解反应谱法计算得到的结构基底剪力与时程分析的结果基本相符。

Study on mode-superposition response spectrum method applied in isolated structure

In the isolated structure design, calculating the structure and isolation layer separately will cause great computational mistake for some layer，because of the unified horizontal seismic decrease coefficient. Using the mode-superposition response spectrum method can get an accurate result of reinforcement assembly and structural deformation. The isolation structure is consisting of the isolation layer and the upper structure, whose damping ratios are different. In the mode-superposition response spectrum method, the way to calculate the isolation structure damping ratio is the key. Through the energy method, the mode damping ratio formula and the simplified form were derived for isolated structure. Using the response spectrum in GB 50011-2010, the earthquake response of isolated structure can be calculated. The application to a 16 stories base-isolation frame shows that the base shear of the frame calculated by mode-superposition response spectrum method agrees well with the result calculated by time history method.