非平稳地震激励下结构随机响应及动力可靠性研究

基于美国西部121条基岩强震加速度记录,采用Hilbert-Huang变换(HHT)生成能真实反映地震记录频率和强度双非平稳特性的非均匀调制演变功率谱,并用经验统计方法建立了根据地震矩震级、震源距预测演变谱的统计模型。运用虚拟激励法得到具有特定震级、震源距的演变功率谱作用下结构的非平稳随机响应特性,同时结合首次超越理论,分析了结构的动力可靠度问题,并且与仅具有强度非平稳特性的均匀调制地震随机激励作用进行比较,结果表明,在总能量相同的情况下,双非平稳功率谱的激励会使结构的响应更大,结构更容易失效。

THE RANDOM RESPONSE AND DYNAMIC RELIABILITY ANALYSIS OF STRUCTURE SUBJECTED TO NoN-STATIONARY SEISMIC EXCITATION

The evolutionary power spectrum reflecting the earthquake energy contribution characteristics on time-frequency plane was estimated by the Hilbert-Huang Transform(HHT),and with reference to the experiential statistical method,an evolutionary spectrum prediction model for given earthquake magnitude and distance was established based on the 121 near-source acceleration records at rock surface with large magnitude from the ground motion database of western U S.The pseudo excitation method was adopted to acquire the solution for linear structural random response under specific non-stationary seismic excitation and structural dynamic reliability was discussed based on the first-excursion failure criterion.The results demonstrated that the non-stationary contents included in seismic excitation would increase greatly the random response and failure probability of structure in comparison with strength non-strationary excitation.