Dynamic Field Response Studies and Earthauqke Instrumentation of the Meloland Road Overcrossing

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by James H. Gates, California Dep of Transportation, Sacramento, United States,

Document Type: Proceeding Paper

Part of: Structural Engineering in Natural Hazards Mitigation:

Abstract: Ambient vibration data was obtained at the Meloland Road Overcrossing near El Centro in California by The California Department of Transportation (CALTRANS) as part of a 1978 Federal Highway Administration (FHWA) research contract. The ambient level survey and results obtained are described. The bridge was also instrumented to record strong motion vibrations in 1978 by the California Strong Motion Instrumentation Program (CSMIP). The multi-channel instrumentation for this bridge is described. Recordings with a maximum acceleration of 0.51g on the bridge and maximum ground acceleration of 0.32g were recorded at the site during the October, 1979 Imperial Valley Earthquake. The results of a system identification analysis of both the ambient and strong motion data are presented. The differences noted between the two levels of vibration are compared. The system identification analysis indicates a significant decrease in overall structure stiffness as the level of excitation is increased. This difference in response is attributed primarily to the non-linear stiffness of the soils at the abutment and column foundations.

Subject Headings: Field tests | Instrumentation | System analysis | Soil dynamics | Highways and roads | Dynamic response | Soil analysis | Vibration | Dynamic structural analysis | Ground motion | Bridges | North America | California | United States

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