MODIFICATION OF SEISMIC INPUT FOR FULLY DISCRETIZED MODELS

概要

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The finite element method together with the solution of the equations of motion in the time domain are often used for seismic analyses of soil-structure interaction problems. In many situations it is reasonable to assume that the base of the finite element model is rigid and hence apply the seismic loading in the form of an accelerogram at the base. Base accelerograms are calculated from available criteria accelerograms, usually recorded at the surface, employing deconvolution analysis based on continuum soil models. However, contrary to theoretical predictions, when the deconvolved accelerograms are input at the base of the finite element model analyzed in the time domain, they do not exactly reproduce the original criteria motion. This discrepancy is attributed to the error characteristics of the discretized model such as cut-off frequency, dispersion and spurious reflections. A simple method is proposed to partly overcome this problem by modifying the base accelerogram employing a one-dimensional soil model which has the same error characteristics as those of the interaction model. This model employs a viscous dashpot at the base. Vertically propagating shear waves are considered.
社団法人地盤工学会の論文
1990-06-15