Seismic Analysis and Testing of Equipment Using Historical Strong Motion Data Scaled To Satisfy Shock Response Spectra Specifications


Abstract eng:
A launch vehicle mounted on a pad at Vandenberg Air Force Base (AFB), California must be able to withstand a potential earthquake per the shock response spectrum (SRS) in the National Aeronautics and Space Administration NASA-HDBK7005 [1], due to the nearby San Andreas Fault. Nuclear, power substation, and telecommunication equipment in active seismic zones must likewise survive spectra given in the Institute of Electrical and Electronics Engineers IEEE Std 6932005 [2] and other standards. Launch vehicles and equipment are idealized as single-degree-of-freedom (SDOF) systems as a first approximation, but are in reality multi-degree-of-freedom (MDOF) systems. The response of an MDOF system to an SRS base excitation can be approximately calculated via the square-root-of-the-sum-of-the-squares (SRSS), National Research Laboratory (NRL) or some other modal combination method. But a time domain direct or modal transient analysis is desired in certain cases, which requires synthesizing a non-unique time history to meet the SRS. Time history synthesis is also needed for testing equipment on a shaker table, although this would be more typical in the nuclear industry than aerospace for seismic events. A common concern, however, is that the synthesized time history may be vastly different than the true source event, which could affect the response in terms of linearity, MDOF behavior, temporal moment energy, etc. This paper demonstrates a method for modifying a representative historical measured time history to satisfy a specified SRS to mitigate this concern. The measured data is decomposed into a series of wavelets as an intermediate step. The wavelets can then be scaled so that the synthesized time history meets the SRS specification. The focus of this paper is on seismic shock, but the method may be adaptable to other types of shock events such as pyrotechnic shock. The results of the method can be used for both transient analysis and shaker table testing.

Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 17.:
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