000013305 001__ 13305
000013305 005__ 20161114160335.0
000013305 04107 $$aeng
000013305 046__ $$k2009-06-22
000013305 100__ $$aVamvatsikos, D.
000013305 24500 $$aEstimating the dynamic instability of oscillators with non-trivial backbones

000013305 24630 $$n2.$$pComputational Methods in Structural Dynamics and Earhquake Engineering
000013305 260__ $$bNational Technical University of Athens, 2009
000013305 506__ $$arestricted
000013305 520__ $$2eng$$aNovel empirical relationships are introduced to estimate the median, mean and dispersion of strength ratios to cause dynamic instability in oscillators with non-trivial backbones and arbitrary periods. The backbones investigated range from a simple bilinear elastic-negative shape to a trilinear that includes an elastic, a hardening and a negative stiffness segment that terminates at zero strength. Using 72 ground motion records that were recorded on firm soil we calculate the mean, median, 16% and 84% percentiles of the corresponding lateral strength ratios required for the appearance of dynamic instability. Processing of the results shows the influence of the oscillator parameters to the occurrence of dynamic instability: Lengthening the oscillator period, delaying the onset of negative stiffness and decreasing the negative slope are all shown to delay the appearance of collapse. On the other hand, contrary to current engineering intuition, increasing the hardening stiffness while maintaining the same period and coincident negative branches has only a small effect on the onset of instability. Using nonlinear regression, parametric equations are developed that can accurately capture such effects in a simple, easy-to-use formula.

000013305 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000013305 653__ $$aOscillator, Hysteretic Systems, Nonlinear Dynamic Analysis, Dynamic Instability, Seismic Performance. Abstract. Novel empirical relationships are introduced to estimate the median, mean and dispersion of strength ratios to cause dynamic instability in oscillators with non-trivial backbones and arbitrary periods. The backbones investigated range from a simple bilinear elastic-negative shape to a trilinear that includes an elastic, a hardening and a negative stiffness segment that terminates at zero strength. Using 72 ground motion records that were recorded on firm soil we calculate the mean, median, 16% and 84% percentiles of the corresponding lateral strength ratios required for the appearance of dynamic instability. Processing of the results shows the influence of the oscillator parameters to the occurrence of dynamic instability: Lengthening the oscillator period, delaying the onset of negative stiffness and decreasing the negative slope are all shown to delay the appearance of collapse. On the other hand, contrary to current engineering intuition, increasing the hardening stiffness while maintaining the same period and coincident negative branches has only a small effect on the onset of instability. Using nonlinear regression, parametric equations are developed that can accurately capture such effects in a simple, easy-to-use formula.

000013305 7112_ $$aCOMPDYN 2009 - 2nd International Thematic Conference$$cIsland of Rhodes (GR)$$d2009-06-22 / 2009-06-24$$gCOMPDYN2009
000013305 720__ $$aVamvatsikos, D.$$iMiranda, E.$$iAkkar, S.
000013305 8560_ $$ffischerc@itam.cas.cz
000013305 8564_ $$s667962$$uhttps://invenio.itam.cas.cz/record/13305/files/CD450.pdf$$yOriginal version of the author's contribution as presented on CD, section: Progress and challenges in collapse prediction - i (MS).
000013305 962__ $$r13074
000013305 980__ $$aPAPER