Physically Based Modeling of Spatially Variable Seismic Ground Motions

基于物理的空间变化地震地面运动建模

• 批准号: 9725567
• 负责人: Aspasia Zerva
• 金额: $ 6.46万
• 依托单位: Drexel University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725567&HistoricalAwards=false
• 关键词: Physically; Based; Modeling; Spatially; Variable

The spatial variation of seismic ground motions has an important effect on the response of lifelines, such as bridges and pipelines; it may induce significant additional loads in the structure than the ones obtained if the structure's supports are subjected to the same seismic motions. The spatial variation of seismic ground motions results from the apparent propagation of the waveforms on the ground surface and the differences in their shape at the various locations of the supporting structure.In a previous study, the PI developed an alternative methodology for the investigation of spatially variable seismic ground motions recorded at dense instrument arrays. It models the seismic motions as superpositions of sinusoidal functions, described by their amplitude, frequency, wavenumber and phase. The application of the methodology to data recorded at the SMART-1 array in Lotung, Taiwan, revealed that the common, coherent component approximates to a very satisfactory degree the actual motions,and that the spatial variability is caused by arrival time delays at the array stations associated with the upward traveling of the waves through the site topography, and by variabilities in both the amplitudes and phases of the motions around the common component characteristics.The developed methodology considers simultaneously the amplitude and the phase variation in seismic motions. Its application to recorded data recognized correlation patterns between amplitude and phase variabilities around a coherent approximation of the motions; this observation may lead to significant developments in the description of spatial variability. However, the methodology has been applied to one site only, and, for the generalization of its results, it is necessary that it be applied at different sites subjected to various earthquakes.Therefore, the present study uses extensive additional sets of data recorded at rock and soil sites. Differentiation is made in terms of the earthquake magnitude: small and large events (e.g., main event andaftershocks) at the same site are investigated. The effect of the water table at the sites ('wet' and 'dry' sites) is also taken into consideration.

地震地面运动的空间变化对生命线（如桥梁和管道）的响应有重要影响;它可能会在结构中产生显著的附加载荷，而不是结构的支撑受到相同的地震运动时获得的载荷。地震地面运动的空间变化是由于地表上波形的明显传播以及支撑结构不同位置处波形的差异造成的。在以前的研究中，PI开发了一种替代方法，用于调查密集仪器阵列记录的空间变化地震地面运动。它将地震运动建模为正弦函数的叠加，由其振幅、频率、波数和相位描述。将该方法应用于台湾罗东SMART-1台阵记录的数据表明，共同的相干分量在非常令人满意的程度上近似于实际运动，并且空间变化是由与波通过场地地形向上行进相关的台阵站的到达时间延迟引起的，该方法同时考虑了地震运动中振幅和相位的变化。它的应用程序记录的数据之间的相关模式的幅度和相位的变化周围的一致近似的运动，这一观察可能会导致显着的发展空间变异性的描述。 然而，该方法仅适用于一个场地，为了推广其结果，有必要将其应用于遭受各种地震的不同场地，因此，本研究使用了大量的岩石和土壤场地记录的数据。根据地震震级进行区分：小事件和大事件（例如，主震和余震）。还考虑了场地（“湿”和“干”场地）地下水位的影响。