摘要
利用谐小波变换对实际强震记录的时变谱进行估计,并统计分析了远场3类不同场地上地震波的时变谱特征,分析发现对于硬场地上的远场地震波在时域内平稳段较短,下降段衰减较快,而在频域内则具有较大的中心频率和较宽的频带.利用均匀调制非平稳模型和时变修正Kanai-Tajimi非平稳模型模拟地震波的时变谱,把非线性函数的参数识别问题转化成求解无约束优化问题,利用拟牛顿迭代法求得最优解,得到3类不同场地上这两种模型的参数具体取值以及参数函数集的具体表达式.为了定量地确定模拟模型的精度,定义了误差函数,验证了所提时变谱参数识别方法的精度,给出了与建筑抗震规范相对应的不同场地不同烈度下多遇和罕遇地震的谱强度因子的大小.最后提出了利用求解时变线性微分方程组来合成非平稳地震波的方法.
Time variable spectra of strong ground motion records are estimated based on the harmonic wavelet transform. The characteristic of time variable spectrum of the strong motion records on the sites of three classes are analyzed. It is shown that the records on hard soil site have shorter stationary duration in time domain,and have higher frequency center and wide frequency band in frequency domain. The average time variable spectra of strong motion records are simulated by uniform non-stationary stochastic model and time variable modified Kanai-Tajimi non-stationary stochastic model. The empirical formulas for the time variable spectra of strong motion records on three class soil sites are established by using nonlinear function fitting method. In order to demonstrate the precision of the simulated stochastic model,an error function is defined and the errors are calculated. The time variable spectrum factors corresponding to relevant seismic intensity and soil site class,which are compatible with the seismic code,are given. Finally,the artificial non-stationary ground motion is generated by solving the time variable linear differential equations.
出处
《地震学报》
CSCD
北大核心
2010年第6期733-743,共11页
Acta Seismologica Sinica
基金
国家自然科学基金项目(50778079)
湖北省自然科学基金项目(2006ABA067)资助
关键词
谐小波变换
时变谱非
平稳随机模型
地震波
harmonic wavelet transform
time variable spectrum
non-stationa-ry stochastic model
ground motion
