近断层地震动和单自由度体系地震反应的分形特征分析  

Fractal characteristic analysis of near-fault ground motions and seismic responses of SDOF systems

作　　者：张长庚[1] 杨迪雄[1] 

机构地区：[1]大连理工大学工程力学系,工业装备结构分析国家重点实验室,辽宁大连116023

出　　处：《地震工程与工程振动》2011年第6期45-54,共10页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(90815023,50978047);中央高校基本科研业务费专项资金项目(DUT11LK06)

摘　　要：从分形几何的新视角出发,分析近断层地震动的不规则性和复杂性。利用盒维数法计算了来自台湾集集地震和美国北岭地震的30条近断层地震动加速度时程的分形维数。计算结果表明,这些地震动加速度时程具有统计分形特征。近断层地震动运动特征对其分维数影响明显,滑冲效应脉冲地震动的分维数平均值最小,向前方向性效应脉冲地震动的分维数平均值居中,无脉冲地震动的分维数平均值最大,其波形不规则程度也最高。而且,地震动时程的分维数反映了其频谱特性,可作为频谱周期的表征参数。地震动的分维数D与特征周期TC具有较强的负相关关系。最后,对于近断层地震动作用下单自由度(SDOF)体系的弹性和非弹性动力反应时程,应用盒维数法计算了其分形维数,考察了其分形性质。From the new perspective of fractal geometry,the irregularity and complexity of near-fault ground motions are analyzed.Based on the method of box dimension,the fractal dimensions of 30 acceleration time histories of near-fault ground motions from Taiwan Chi-Chi earthquake and California Northridge earthquake are calculated.Numerical results indicate that the acceleration time histories of ground motions present the statistical fractal property,and the influence of motion characteristic of near-fault ground motions on their fractal dimensions is remarkable.The average fractal dimension of near-fault impulsive ground motions with fling step is the smallest,and the average fractal dimension of impulsive ground motions with forward directivity is middle,while the mean fractal dimension of non-pulse ground motions is the largest and the irregular degree of wave forms is the highest.Moreover,the fractal dimensions of ground motions reflect their frequency property,and can be regarded as an index to represent their frequency content.The fractal dimension D and characteristic period TC of ground motions have the negative correlation distinctly.Finally,for the time histories of seismic dynamic responses of elastic and inelastic single degree of freedom（SDOF） systems subjected to near-fault ground motions,the fractal dimensions are computed via the box dimension,and the fractal property is examined.

关 键 词：近断层地震动 分形维数 盒维数 SDOF体系地震反应 分形特征 

分 类 号：P315.91[天文地球—地震学] TU352.1[天文地球—固体地球物理学]