基础隔震高层建筑结构减震系数研究

Seismic reduction coefficient of base-isolated high-rising building structures

针对质量、刚度沿高度分布相对均匀的基础隔震高层建筑结构建立其等效梁模型,基于振型分解反应谱法对隔震及非隔震结构振型数、振型参与质量、地震剪力、力矩等关键指标进行探讨分析。给出了确定水平向减震系数指标的临界刚度比、临界周期比,进一步分析了该两个临界比值对减震系数的一般性控制规律。研究结论表明:当隔震后、前结构基本周期比r_(T1)>1.3或上部结构整体等效刚度与隔震层水平等效刚度之比r_(kh)>0.8时,可有效抑制高层剪力墙隔震结构高阶振型反应,仅需考虑基本振型对结构地震反应的贡献;结构隔震后、前的底部剪力比、力矩比与上部结构整体等效刚度与隔震层水平等效刚度之比r_(kh)、基本周期比r_(T1)有关,与质量、阻尼等参数无关;当r_(kh)小于临界刚度比r_(kh)B或r_(T1)小于临界周期比r_(T 1B)时,底部力矩减震效果较剪力要差,应以隔震后、前结构底部力矩比作为减震效能评价指标,当r_(kh)大于临界刚度比r_(kh)B或r_(T1)大于临界刚度比r_(T 1B)时,则应以底部剪力比作为评价指标。其中,r_(kh)B,r_(T 1B)可按该研究所给数值取用。所得相关研究成果可为相关理论研究及工程应用提供参考和依据。

An equivalent beam model was established for a base-isolated high-rising building structure with relatively uniform mass and stiffness distribution along the height.Based on the method of vibration mode decomposition response spectrum,the key indexes of vibration mode number,vibration mode participation quality,seismic shear force and moment of isolated and non-isolated structures were discussed and analyzed.The critical stiffness ratio and critical period ratio of the horizontal seismic reduction coefficient were given,and the general control rule of the two critical ratios on the seismic reduction coefficient was further analyzed.The study concluds that:when the basic period ratio r_(T1)>1.3 or the equivalent stiffness ratio r_(kh)>0.8,the high-order vibration mode response of the isolated structure can be effectively suppressed,and only the influence of the basic mode on the seismic response of the structure needs to be considered.The base shear force ratio and moment ratio of the structure after and before being isolated are related to the ratio of the overall equivalent stiffness of the superstructure to the horizontal equivalent stiffness of the isolation layer as well as to the basic period ratio,and have nothing to do with the parameters such as mass and damping.When r_(kh)<r_(kh)B(critical value of r_(kh))or r_(T1)<r_(T 1B)(critical value of r_(T1)),the base moment reduction effect is worse than that of the shear force,so the bottom moment ratio should be taken as a control index;or otherwise,the base shear force ratio should be taken as a the control index when r_(kh)>r_(kh)B or r_(T1)>r_(T 1B).The values of r_(kh)B and r_(T 1B) can be determined in accordance with the data given in the paper.The research results can provide a reference and basis to the related further theoretical research and engineering application.