Investigation of Long-Period Ground Motion in the NorthridgeEarthquake of January 17, 1994.

1994 年 1 月 17 日北岭地震中长周期地面运动的调查。

• 批准号: 9413273
• 负责人: Wilfred Iwan
• 金额: $ 2.27万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-06-01 至 1995-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9413273&HistoricalAwards=false
• 关键词: Investigation; Long; Period; Ground; Motion

9413273 Iwan The Northridge earthquake of January 17, 1994 yielded what may prove to be the most valuable set of strong motion data ever obtained from an earthquake. These data include the largest horizontal ground motion ever recorded. The damage associated with these large ground motions is well documented. In some of the near-field accelerograms, particularly the Sylmar station, there is evidence of a significant long period displacement pulse in the ground motion. The existence of such motion has recently been the subject of great concern as it relates to the design of base isolated and high-rise structures. These structures are particularly susceptible to large input displacements. There is a recognized need to better understand the nature of this long period motion and, ultimately, to be able to model and predict is occurrence. Present routine techniques for the processing of strong motion data tend to remove or distort the long-period information from recorded accelerograms. However, under a recent NSF exploratory grant, techniques have been developed to recover much of the long-period information in accelerograms. This is accomplished by nontraditional baseline correction and signal processing that is based on an improved understanding of the physics of the ground motion and the nature of the recording instruments. The techniques have been verified for ground motions from the Landers earthquake. The goal of this research program is to apply the recently developed data processing techniques to a suite of earthquake records from the Northridge earthquake. The ultimate goal is to provide a basis for guidelines that may be used to characterize the long-period content of earthquake motion for structural design. This exploratory investigation addresses the following questions: 1. What is the nature of the long period (displacement) content of ground motion from this type of thrust earthquake? 2. How does this vary with distance from th e epicenter and orientation with respect to the fault plain. 3. How is the long-period content (peak displacement) related to the short-period content (peak acceleration)? 4. What generalizations can be made to future events of this, or another, type? 5. Is there a correlation between the observed long-period ground motion and structural damage? The research is based on digital data obtained from the California Division of Mines and Geology and the U.S. Geological Survey. ***

1994年1月17日的北岭地震产生了可能被证明是迄今为止从地震中获得的最有价值的一组强震数据。这些数据包括有记录以来最大的水平地面运动。与这些大的地面运动有关的损害是有据可查的。在一些近场加速度计中，特别是Sylmar站，有证据表明地面运动中存在明显的长周期位移脉冲。这种运动的存在已成为近年来备受关注的主题，因为它涉及到基础隔离和高层结构的设计。这些结构特别容易受到大输入位移的影响。人们认识到需要更好地了解这种长周期运动的本质，并最终能够建立模型并预测其发生。目前处理强运动数据的常规技术往往会从记录的加速度图中删除或扭曲长周期信息。然而，在美国国家科学基金会最近的一项探索性资助下，已经开发出技术来恢复加速度图中的大部分长期信息。这是通过非传统的基线校正和信号处理来实现的，这是基于对地面运动物理和记录仪器性质的更好理解。这些技术已经在兰德斯地震的地面运动中得到了验证。本研究项目的目的是将最新开发的数据处理技术应用于北岭地震的一套地震记录。最终目的是为结构设计中描述地震运动的长周期内容提供指导依据。这个探索性调查解决了以下问题：1。这种逆冲地震的长周期（位移）地面运动的性质是什么？2. 这是如何变化的距离震中和方向相对于断层平原。3. 长周期内容（峰值位移）与短周期内容（峰值加速度）之间的关系如何？4. 对这种或另一种类型的未来事件可以做出什么概括？5. 观察到的长周期地面运动和结构破坏之间是否存在关联？这项研究是基于从加州矿业和地质部门以及美国地质调查局获得的数字数据。＊＊＊