Time-history analysis provides for linear or nonlinear evaluation of dynamic structural response under loading which may vary according to the specified time function. Dynamic equilibrium equations, given by K u(t) + C d/dt u(t) + M d2/dt u(t) = r(t), are solved using either modal or direct-integration methods. Initial conditions may be set by continuing the structural state from the end of the previous analysis. Additional notes include:
- Step Size – Direct-integration methods are sensitive to time-step size, which should be decreased until results are not affected.
- HHT Value – A slightly negative Hilber-Hughes-Taylor alpha value is also advised to damp out higher frequency modes, and to encourage convergence of nonlinear direct-integration solutions.
- Nonlinearity – Material and geometric nonlinearity, including P-delta and large-displacement effects, may be simulated during nonlinear direct-integration time-history analysis.
- Links – Link objects capture nonlinear behavior during modal (FNA) applications.
|List of resources2|
|drafts-root||Time history analysis drafts|
|*Related Email:* * [7/14/2010 email from bm: Impact of time-step size (relative to modal periods) on results|$3145753] *Related Incident:* * 26167: Explains reason for inconsistent results for acceleration time-history input and displacement time-history input|