【摘要】 介绍了Hilbert-Huang变换的原理和波内调制的概念,对比了地震动作用下单自由度和多自由度结构的线性体系与三线性刚度退化体系绝对加速度响应的Hilbert幅值谱、能量谱,分析系统进入非线性力学状态的重要标志。结果表明:"频带展宽"和"优势频率漂移"是体系动力响应非线性力学行为的两个重要标志。线性体系加速度响应的能量集中在自振频率附近的窄小频带内;而三线性刚度退化体系由于波内调制的原因使Hilbert能量谱频带展宽。并且,能量谱的优势频率受体系屈服频率和开裂频率的影响向低频漂移。在短周期结构中,频带展宽和优势频率漂移较显著,而在长周期结构中表现不明显。更多还原

【Abstract】 Hilbert spectrum and intra-wave modulation were introduced here.For a SDOF system and a MDOF system,Hilbert amplitude spectra and energy spectra of the absolute acceleration responses under earthquake for both their tri-linear stiffness retrograde systems and their linear systems were compared.The symbols of the non-linear mechanical behavior were analyzed.It was shown that band broadening and dominant frequency drift are two important symbols of the nonlinear mechanical behavior of the dynamic response of a system;the acceleration energy of a linear system is concentrated in a narrow frequency band near its natural frequency and intra-wave modulation causes band broadening in Hilbert energy spectrum of a tri-linear stiffness degradation system;due to influence of yield frequency and cracking frequency,the dominant frequency of the energy spectrum drifts to lower frequency;in short period structures,band broadening and dominant frequency drift are obvious,but in long period structures,they are not significant.更多还原