Damping Variations in Structures


Abstract eng:
The frequency and damping of an engineering structure control its dynamic response via Newton’s second law. These two modal parameters are likely to vary in time due to environmental conditions, to the appearing of damage in the system or to dynamic loading. These variations lead to a modification of its vulnerability but their analysis could thus give information on the state of health of the monitored structure. Being related to energy dissipation, damping is also a critical parameter to be determined for risk assessment for any engineering structure. Its precise evaluation is thus primordial but its measure is riddled with uncertainty considering the very strong scattering of its monitoring over time even if solicitation remains at ambient vibration level. Any dependency of damping on the noise amplitude has been ignored so far. However, experimental results on metric beams in the lab representing simplified building models exhibit a positive correlation between damping and acceleration whereas frequency remains constant. Their linear definitions command an equal relative variation of these two for any alteration of the structure's stiffness. This violation of the linear assumption is yet explained by mathematical results derived from the Helmholtz equation and the fluctuation-dissipation theorem which lead to the expression of a specific attenuation proportional to the noise intensity.

Contributors:
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 4194.:
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