Double Resonance of Structures in San Fernando Valley During the Northridge Earthquake of January 17, 1994

该项目的目的是获得圣费尔南多谷地区地面运动的主要振动频率，并将其与1994年1月17日北岭地震中遭受重大破坏的几个关键结构的共振频率进行比较。这种比较允许“双共振”的识别。（当地面的基频周期与结构的谐振频率重合时，就会发生双共振。）具体任务包括：(1)测量在地震中遭受严重破坏的公路桥梁和立交桥的长周期微震反应（微震是自然发生的地面振动）；(2)测量圣费尔南多谷内70个地点的长周期微震反应，并在参考基岩地点同步记录。＊＊＊

9412759 Dravinski The objective of this project is to obtain the predominant frequencies of vibration of ground motion in the San Fernando Valley area, and to compare them with the resonant frequencies of several key structures which suffered significant damage during the Northridge earthquake of January 17, 1994. This comparison permits the identification of "double resonance". (Double resonance occurs when the fundamental period of the ground coincides with the resonant frequency of the structure.) The specific tasks include: (1) the measurement of long-period microtremor response at highway bridges and overpasses which suffered severe damage during the earthquake (microtremors are naturally-occurring ground vibrations), and (2) measurement of long period microtremor response at seventy sites within the San Fernando Valley with simultaneous recordings at a reference bedrock site. ***