摘要
首先引入具有统计参数的时-频包线函数,近似模拟地震动频率的非平稳特性,建立了能够匹配多目标的空间相关多点非平稳地震动拟合方法,实现了近似定量控制输入地震动特性的目标;然后以天然地震动为种子,分别采用3种不同的包线函数基于多个拟合目标进行地震加速度时程的模拟,建立了满足不同频谱特性的地震动输入方案;最后分别采用一致和多点地震动输入模式,对大跨结构进行非线性响应分析。结果表明:(1)建立的空间相关多点非平稳地震动拟合方法,能够较好地模拟地震动频率非平稳特性及空间变化,且拟合精度较高,能够实现对输入地震动的定量控制;(2)具有统计参数的时-频包线函数能够较好地表征地震动频率非平稳特性,与真实地震动频率随时间的变化规律符合较好;(3)无论采用一致或多点地震动输入模式,仅考虑地震动强度非平稳特性,存在低估结构非线性响应的风险;(4)对于大跨结构,一致地震动输入模式存在低估桥梁结构位移响应的风险。因此,大跨结构抗震分析中应合理刻画地震动时间-空间耦合特性,估计结构的非线性响应,保证结构设计的安全性。
It is vital to evaluate the effects of spatial variation and the frequency non-stationarity of earthquake ground motion on the structural responses.Firstly,by introducing a frequency-dependent amplitude envelope function with statistical parameters to simulate the non-stationarity of frequency in earthquake ground motion,the simulation method of spatial correlation multipoint ground motion is developed,which can match multiple targets and can consider the non-stationarity of frequency in ground motion simultaneously.Secondly,three sets of acceleration time histories for the same target spectrum are successfully obtained through three different methods by taking the natural ground motion as the seed.Finally,these time-histories are used to analyze the nonlinear response of structure under the multipoint or uniform input.The results suggest that:(1)The fitting method of spatial correlation multipoint ground motion can reflect the frequency non-stationary and the spatial variation of ground motion with higher fitting precision;(2)The time-frequency envelope function with statistical parameters can better simulate the frequency non-stationary of the ground motion,which agrees with the frequency time-variation of the natural ground motion;(3)Regardless of the uniform or multipoint inputs,the earthquake ground motion only considering the non-stationarity of intensity will have the risk of underestimating the structural nonlinear response;(4)For large-span structures,there is the risk of underestimating the structural displacement response under the uniform earthquake input.Collectively,in the seismic analysis of long-span structures,the time-space coupling characteristics of ground motion should be considered in the simulation of the artificial ground motion so as to evaluate the structural nonlinear responses reasonably and guarantee the safety of the structure design.
作者
俞瑞芳
曲国岩
张冬锋
YU Rui-fang;QU Guo-yan;ZHANG Dong-feng(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Logistics Department,Nankai University,Tianjin 300071,China)
出处
《振动工程学报》
EI
CSCD
北大核心
2020年第5期1013-1023,共11页
Journal of Vibration Engineering
基金
国家自然科学基金资助项目(51878627,51478440)。
关键词
大跨结构
多点地震动合成
空间变化
频率非平稳特性
结构非线性响应
large-span structure
simulation of multi-supported earthquake
spatial variation
non-stationarity of frequency
structural nonlinear responses
