基于虚拟激励法的隔震LNG储罐随机地震响应分析

Random seismic response analysis of LNG storage tanks based on pseudo excitation method

基于等效线性化法和虚拟激励法,对地震激励下的圆柱形LNG(液化天然气)隔震储罐进行了随机振动分析,研究了隔震储罐的液位与形状对随机地震响应的影响。首先,基于加速度反应谱,根据Kaul方法得到了地震动功率谱密度函数,并建立了LNG储罐的HarounHousner模型。其次,根据等效线性化方法得到了隔震系统的等效刚度和等效阻尼,建立了等效线性系统的频域运动方程,并应用虚拟激励法进行求解。最后,在数值算例中,计算了不同液位与半径下隔震储罐的随机响应,研究了储罐半径和液位高度对响应的影响,为隔震储罐的优化设计提供一定的参考。

This paper bases on the equivalent linearization method and pseudo excitation method to conduct random vibration analysis of cylindrical LNG isolation tanks under seismic excitation and investigates the influence of the liquid level and shape of the isolation tanks on the random seismic response.First,based on the acceleration response spectrum,a seismic power spectral density function is obtained according to the Kaul method,and a Haroun-Housner model of the LNG tank is established.Second,the equivalent stiffness and damping of the isolation system are obtained according to the equivalent linearization method,and the frequency domain equations of motion of the equivalent linear system are established,and a pseudo excitation method is developed to solve them iteratively.Finally,numerical examples are given,where the random responses of isolated storage tanks under different liquid levels and radii are calculated and the effects of tank radius and liquid level height on the response are studied,so as to provide certain reference for the optimization design of isolated storage tanks.