Response behavior of a nonlinear structural system subject to environmental loadings
is investigated in this study. The system contains a nonlinear restoring force due to large
geometric displacement. The external excitation is modeled as a narrowband stochastic
process possessing dynamic characteristics of typical environmental loadings.
A semi-analytical method is developed to predict the stochastic nonlinear response
behavior under narrowband excitations in both the primary and the subharmonic resonance
regions. Preservation of deterministic response characteristics under the narrowband random
field is assumed. The stochastic system response induced by variations in the narrowband
excitations is considered as a sequence of successive transient states.
Due to the system nonlinearity, under a combination of excitation conditions, several
response attraction domains may co-exist. Presence of co-existence of attraction domains and
variations in the excitation amplitude often induce complex response inter-domain transitions.
The response characteristics are found to be attraction domain dependent. Among different
response attraction domains, their corresponding response amplitude domains overlap. In
addition, within an individual attraction domain, response amplitude domains corresponding
to different excitation amplitudes also overlap. Overlapping of response amplitude domains
and the time-dependent variations in the excitation parameters induce response intra-domain
transitions.
Stationary Markovian assumption is employed to characterize the stochastic behavior of the response amplitude process and the excitation parameter processes. Based on the stochastic excitation properties and the deterministic response characteristics, governing equations of the response amplitude probability inter- and intra-domain transitions are formulated. Numerical techniques and an iteration procedure are employed to evaluate the stationary response amplitude probability distribution.
The proposed semi-analytical method is validated by extensive numerical simulations. The capability of the method is demonstrated by good agreements among the predicted response amplitude distributions and the simulation results in both the primary and the subharmonic resonance regions. Variations in the stochastic response behavior under varying excitation bandwidth and variance are also predicted accurately. Repeated occurrences of various subharmonic responses observed in the numerical simulations are taken into account in the proposed analysis. Comparisons of prediction results with those obtained by existing analytical methods and simulation histograms show that a significant improvement in the prediction accuracy is achieved. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33585 |
| Date | 10 June 1998 |
| Creators | Shih, I-Ming |
| Contributors | Yim, Solomon C. S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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