Influence of Soil-Structure Interation on Motions Recorded at the Jensen Filtration Plant during Northridge Earthquake & Aftershocks & its Implications for Nonlinear Site R

1994年北岭地震序列（主震和余震）期间，詹森过滤厂（JFP）记录的强地面运动为研究土壤非线性提供了机会。 在JFP的两个靠近的地震站记录了地震运动;一个地震站位于中等硬度的土壤上，另一个位于非常坚硬的土壤上。 这两个记录的特点，这是完全不同的，这表明在中等刚度的土壤网站的非线性土壤反应。 不幸的是，记录运动的两个建筑物在施工中并不相同;这就提出了一个问题，即土-结构相互作用（SSI）是否影响了一个或两个台站的运动。美国地质调查局（USGS）维护、检索、处理和传播JFP记录的强震数据。 美国地质勘探局的研究人员研究了这些记录的非线性现场反应，他们的研究结果表明，SSI效应可能会影响结果。 首席研究员最近完成了一项研究计划，该计划涉及对JFP两栋建筑物的动态SSI调查：3层的主行政大楼（JMB）和小得多的1层发电机大楼（JGB）。该行动将继续执行以下任务：（1）分析惯性SSI效应的动态试验数据，（2）分析运动学相互作用（建筑物地基的高频滤波）基于北岭地震和其他地震期间在其他地点记录的数据，（3）分析JMB和JGB站以及美国地质勘探局最近安装的新的JMB和JGB自由场站同时记录的运动;（4）建立JMB和JGB站的SSI分析模型;（5）修正SSI的JMB和JGB强震记录;（6）重新评估非线性场地反应（与美国地质勘探局研究人员合作），（7）准备一份技术报告，然后发表期刊。这项调查的最终目标是进一步了解弱，中，和强烈的地面震动 研究结果有望为非线性场地响应提供更多的见解，并在未来的地震强地面运动衰减和场地响应模型的改进中考虑非线性场地响应。

The strong ground motions recorded at the Jensen Filtration Plant (JFP) during the 1994 Northridge earthquake sequence (mainshock and aftershocks) provide an opportunity to study soil nonlinearity. Two stations close together at the JFP recorded the earthquake motions; one station was situated over moderately stiff soil, the other on very stiff soil. The characters of the two recordings, which were quite different, suggest nonlinear soil response at the moderately stiff soil site. Unfortunately the two buildings where the motions were recorded were not identical in construction; this raises the issue whether soil-structure interaction (SSI) affected the motions at one or both stations.The United States Geological Survey (USGS) maintains, retrieves, processes and disseminates the strong motion data recorded at JFP. USGS researchers have studied these records for nonlinear site response, and their findings suggest that SSI effects may be affecting the results. The principal investigator recently concluded a research program involving dynamic SSI investigations of both JFP buildings: the 3-story main administrative building (JMB) and the much smaller 1-story generator building (JGB).This action is to continue the program with the following tasks: (1) analyze the dynamic test data for inertial SSI effects, (2) analyze kinematic interaction (high frequency filtering by the building foundation) based on data recorded at other sites during the Northridge and other earthquakes, (3) analyze motions recorded simultaneously at the JMB and JGB stations and at new JMB and JGB free-field stations recently installed by the USGS, (4) construct SSI analytical models for the JMB and JGB stations, (5) correct the JMB and JGB strong motion records for SSI, (6) reassess nonlinear site response (in cooperation with USGS researchers), and (7) prepare a technical report followed by journal publications.The ultimate objective of this investigation is to further the understanding of nonlinear site response during weak, moderate, and very strong ground shaking. The results are expected to provide additional insights into nonlinear site response, and its consideration in future refinements of attenuation and site-response models of earthquake strong ground motions.