Numerical Research on the Equivalent Transformation Between Structural Dynamic Analysis in Time-Domain and Frequency Domain

Abstract eng:
Numerical analysis methods in time-domain and frequency-domain are commonly considered as two important ways for seismic evaluation of structure responses. In terms of the seismic wave excitation and the structural output response, the expressions of time histories are usually applied in the time-domain method, while the complex harmonic waves or their summation generally used in the frequency-domain method, it is a focus in the field of structure engineering to construct equivalent expressions of seismic wave excitation and structural responses between time-domain and frequency-domain solution methods. In this paper, as far as general dynamic analysis of structure is concerned, a formula of trigonometric coefficients in time domain is deduced to compute frequency spectrum values at arbitrary frequency points for time history data, which avoids the disadvantage of the conventional discrete Fourier transform (DFT) method that merely suiting for the discrete frequency points. Hence, according to the seismic analysis of structural responses, a quantified assessment of equivalent expressions for various wave signals are given in detail, which builds a transformation bridge between time-domain and frequency-domain solution methods. Finally, the validity and feasibility of the transformation algorithm in time-domain and frequency-domain are numerical verified by the dynamic response analysis of multiple particles damp system and long span structure with seismic wave excitations. It’s also shown from the results, as the trigonometric coefficient method (TCM) is concerned, only inputted the real part or the imaginary part of the seismic wave exaction time history, the equivalence response of structure in frequency domain can be obtained by a simple combination of trigonometric coefficients in time domain.

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