We are seeking a Mendenhall Fellow to study variation of modal properties from the ambient to the strong motion regime of vibrations. Comparison of modal properties that are obtained through the analysis of vibration data collected from a structure during its operational (i.e., ambient) conditions with those results extracted from the structure's response recorded during seismic events (i.e., strong shaking) reveals two major trends: decreased modal frequency and increased damping during strong shaking – even though it has been found in several studies that critical damping ratios are in general smaller than used in design practice. While the amplitude dependencies described above are well known, the tendency in the current state of earthquake engineering practice is to accept the dynamic characteristics (frequencies, damping ratios, and mode shapes) observed during low-amplitudes of motion in lieu of those that structures exhibit during strong ground shaking.
Research proposals are invited to identify and characterize the aforementioned variation of dynamic structural characteristics by addressing the following issues:
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Development of predictive relationships for deducing modal properties of building structures during strong motion events from those identified through the analysis of ambient vibration data.
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Investigation of the soil-structure interaction effects on the amplitude dependency of the dynamic characteristics of structures.
The effort by the postdoctoral fellow may include the development and deployment of techniques and tools to be able to efficiently process large quantities of data. Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
Proposed Duty Station: Moffett Field, CA
Areas of PhD: Civil/structural/earthquake engineering or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).
Qualifications: Applicants must meet the qualifications for: Research Civil Engineer
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)
Human Resources Office Contact: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov
