Low Frequency Characterization of Coherency Functions for Spatially Varying Earthquake Ground Motion

空间变化地震地面运动相干函数的低频表征

• 批准号: 9710953
• 负责人: Ronald Harichandran
• 金额: $ 3.92万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-10-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9710953&HistoricalAwards=false
• 关键词: Low; Frequency; Characterization; Coherency; Functions

ABSTRACT: CMS-9710953, Ronald Harichandran, Michigan State U. Observations from closely-spaced seismograph arrays since the late 1970's have shown that earthquake ground accelerograms measured at different locations within the dimensions of typical large engineered structures are significantly different. This has resulted in considerable attention being given to the modeling of spatially varying earthquake ground motions, and on determining its effect on the seismic response of large structures such as bridges, pipelines, and dams. Studies on various structural systems have shown that including the effect of spatially varying earthquake ground motions often increases critical responses, and hence large structures designed without consideration for this phenomenon may be unsafe. A key component in the characterization of spatially varying earthquake ground motions is the coherency function, which describes the incoherence between accelerations recorded at different spatial locations. Different functional forms have been proposed by different investigators for coherency functions, but studies on how these different forms affect the computed responses have been few. Also, since the low- frequency variation of coherency is significantly different among some of the commonly used models, it is critical to resolve contradictions and provide guidance to engineers. The objective of this research program is to use the high- resolution maximum entropy spectral estimation method and long-duration accelerogram records to resolve these contradictions, using records from the Valley of Mexico, the SMART-1 array in Taiwan, the Chiba array in Japan, and the Northridge earthquake in the U. S. This project is a cooperative research program with the Universidad Nacional Autonoma de Mexico (UNAM), involving a joint collaboration between a U. S. engineer, a Mexican engineer, and a Mexican seismologist.

摘要：CMS-9710953，罗纳德Harichandran，密歇根州立大学。 自20世纪70年代后期以来，从密集地震仪阵列的观测表明，在典型大型工程结构尺寸内的不同位置测量的地震地面加速度记录有显著差异。这导致人们对空间变化地震地面运动的建模以及确定其对桥梁、管道和水坝等大型结构地震响应的影响给予了相当大的关注。对各种结构系统的研究表明，考虑空间变化的地震地面运动的影响往往会增加临界响应，因此，设计时不考虑这种现象的大型结构可能是不安全的。 空间变化的地震地面运动的特征的一个关键组成部分是相干函数，它描述了在不同的空间位置记录的加速度之间的不相干性。不同的研究者提出了不同的相干函数形式，但关于这些不同形式对计算响应的影响的研究却很少。此外，由于在一些常用的模型中，相干性的低频变化显著不同，因此解决矛盾并为工程师提供指导至关重要。 本研究计划的目的是使用高分辨率最大熵谱估计方法和长时程加速度记录来解决这些矛盾，使用来自墨西哥谷、台湾SMART-1台阵、日本千叶台阵和美国北岭地震的记录。S. 该项目是与墨西哥国立自治大学（UNAM）的一项合作研究计划，涉及到美国一家大学和墨西哥国立自治大学之间的联合合作。S.一位墨西哥工程师，一位墨西哥地震学家。