空间相关多点多维地震动的模拟  

Simulation of multi-point and multi-dimension spatially correlated earthquake ground motions

作　　者：李忠献[1] 李笑穹 李宁[1] 

机构地区：[1]天津大学滨海土木工程结构与安全教育部重点实验室,天津300072

出　　处：《地震工程与工程振动》2014年第4期64-72,共9页Earthquake Engineering and Engineering Dynamics

基　　金：国家重点基础研究发展计划(973计划)项目(2011CB013603);国家自然科学基金重大研究计划项目(91315301)

摘　　要：对大跨度结构的地震响应分析应考虑地震动的空间效应。采用合理的功率谱、相干函数和传递函数模型,基于原型谱表示法,得到基岩和地表处的空间相关多点多维人工地震动模拟方法,并通过实例验证模拟方法的可行性。结果表明:局部场地条件对入射波产生放大和过滤效应,导致其振幅和频率成分明显改变,在特定的场地条件下,其影响远大于行波效应和相干效应;在对大跨度结构进行地震响应分析时,采用合理考虑局部场地效应的空间相关多点多维地震动模型作为激励输入是非常必要的;在采用数值方法模拟人工地震动时,由于相干函数存在临界值,可以将多维多点地震动简化为三个单维多点地震动的模拟。该模拟方法可以作为实际工程中大跨度结构的地震响应分析获得地震输入的一种有效途径。Spatially varying ground motions should be considered during the seismic response analysis of long-span structures. Based on original spectral representation method, a simulation method for multi-component and multisupport ground motions on both bedrock and surface considering spatial correlation is developed, with reasonable spectral density function, coherence function and site transfer function, and the feasibility of the method is verified by an example. Results show that amplification and filtering effects on the incident wave from local site conditions lead to obvious changes in its amplitude and frequency components, even much greater than changes caused by wave propagation effects and coherency effects under specific site conditions. It＇ s necessary to use non-uniform spatially varying ground motions with rational consideration of local site effects as input during seismic analysis in long-span structures. Simulation of multi-point three-dimensional ground motions can be simplified to three independent multi-point one-dimensional ground motions owing to the critical value of coherency functions through numerical method. Therefore this simulation method offers an effective seismic input way in practical engineering seis- mic response analysis of long-span structures.

关 键 词：地震动 空间相关 场地效应 多点多维 功率谱密度 数值模拟 

分 类 号：P315.9[天文地球—地震学]