地震工况下考虑主体结构塑性损伤致调谐阻尼器频率偏差影响分析

Study on the frequency deviation of the tuned damper effect on structure due to the plastic damage under earthquake

调谐液体阻尼器在地震下无法锁死,而中大地震下结构塑性损伤会导致调谐阻尼器频率偏差(失调谐),研究调谐阻尼器频率偏差对结构的负面效应对其抗震设计非常重要。本文给出了基于频响函数得到的主结构和调谐阻尼器阻尼比对调谐阻尼器处于不同频率偏差时减振率的影响。为进一步考虑中大地震下主结构塑性损伤,将一个高层建筑弹塑性结构等效为单自由度非线性结构,输入183条天然波计算有控结构和无控结构在设防地震、罕遇地震和极罕遇地震下的顶点位移响应。结果表明,地震工况下,调谐阻尼器加剧了有控结构在大震下响应的离散性。不计调谐阻尼器的阻尼效果、仅将调谐阻尼器考虑为固定质量加在结构顶部,有概率低估了调谐阻尼器对结构的负面效果。建议考虑调谐阻尼器的动力效应,采用概率统计方式估计结构的最大负面效应。基于正态分布假定,本文给出了中大震下99%保证率的有控结构振幅放大系数与延性系数计算公式,可为相关工程设计提供帮助。

The plastic damage of the structures during earthquake causing the plastic damage of the main structures may lead to the frequency deviation(miss⁃tuned)of the tuned liquid dampers.The damping effect of the tuned damper is obtained at different frequency deviations under various damping ratios of the main structure and the tuned damper by frequency response function.To further consider the influence of plastic damage of the main structure during earthquake,a single⁃degree⁃freedom nonlinear structure is built to simplify a high⁃rise building.A nonlinear time history analysis of the equivalent structure with and without tuned dampers is conducted with 183 pieces of natural earthquake records.The earthquake records are set to the peak acceleration of the design earthquake,rare earthquake,and extremely rare earthquake stipulated by Chinese code.The conclusions are that,under actual seismic conditions,the discreteness of the response of the structure with a tuned damper increases under rare earthquakes.Considering a tuned damper as a fixed mass added to the top of the structure and ignoring the damping effect,there is still a probability of underestimating the negative effects of the tuned dampers on the structure.It is recommended to use a probabilistic statistical method to estimate the maximum negative effect of the tuned damper.Assuming the negative effect consistent with normal distribution,an equation is proposed to predict the amplification factor of the negative effect of the structure with 99%guarantee rate during earthquake,and the equation may provide references for the design of tuned dampers.