土-结构系统随机地震响应的频-时域影响函数法

Influence Function Method for Random Seismic Response of Soil-Structure System

提出了分析土-结构系统随机地震响应的频-时域影响函数法。假定地震激励为具有演变谱的非平稳 Gauss 过程,土-结构系统为具有滞后型材料阻尼的线性时不变系统。采用频域的有限元复反应分析方法,首先确定土-结构系统的频率影响函数,然后通过快速富氏逆变换求得单位脉冲影响函数,根据线性时不变系统对随机激励的传递关系,确定系统非平稳均方响应及其谱参数,由此确定系统响应的概率分布特征和统计参数以及系统的动力可靠度。分析结果表明,频-时域影响函数法是考虑土与结构相互作用时分析结构动力可靠度的一种有效方法,数值结果显示,由平稳地震激励过程得到的动力可靠度小于按对应的调制非平稳激励过程得到的动力可靠度。

An influence function method is proposed in this paper for non-stationary random response of soil-structure system under seismic excitation.The seismic excitation is assumed as a non-stationary Gaus- sian process with evolutionary spectral density and the soil-structure system as a time-invariant linear sys- tem with hysteretic material damping.The finite element method for complex response in frequency do- main is used to determine the frequency influence function of soil-structure system.The unit impulse influ- ence function is obtained by inverse FFT from the corresponding frequency influence function.According to the transfer behavior of time-invariant linear system to random excitation,the non-stationary mean square responses and their spectral parameters are obtained.These parameters are then used to calculate the dynamic reliability of the system.Numerical calculation shows that the proposed method is an effective approach for dynamic reliability analysis of soil-structure interaction.Sample results indicate that under- estimated dynamic reliability may be obtained from stationary process compared with the corresponding modulated non-stationary process.