Departmental Bulletin Paper CIP法による3次元弾性体の波動伝播解析

佐々木, 豊  ,  柳川, 智隆  ,  松下, 周平  ,  吉田, 長行

地震波解析にはよく有限要素法(FEM)が用いられる。しかし、FEMでは境界処理を行わなければならない。本研究では境界処理法としてCIP法を用いる。3次元解析への拡張を見据え、2次元解析にてFEMとCIP法の結合解析を行った。解析においてOpen Boundary Side scheme(OBS)とOpen Boundary Cell scheme(OBC)の2つの結合手法を用いた。また、波動伝搬においてSH波問題とP・SV波問題を扱い、結合解析の有効性を確認した。
When we calculate the earthquake response of the building, the effect of Dynamic Soil-Structure Interaction is considered. Generally the finite element method (FEM) is used to analyze the dynamic behavior of the soil. This method is well-known to be effective in dealing with the nonlinear behavior. The analytical domain of the FEM has to be closed with the boundaries. But the dissipated wave is propagated over the boundaries and not reflected. Therefore some numerical technique is required to realize the open boundary. The advection equation can decompose the wave of the field into the incoming wave and the out-going one. This property enables us to make the open boundary processing for the FEM analysis. The CIP (Constrained Interpolation Profile Scheme) method is a typical procedure with high precision for the advection equation. This paper investigates the basic characteristics of the CIP method for the transmission of the out-going wave against the three dimensional elastic field. Keywords : Elastic wave, CIP method, Three dimensional field, Open boundary
When we analyze wave propagation, we have to model the ground as if it is extended infinitely in the limited analytical region. Now we try to make an infinite ground model by FEM and CIP combined method. CIP method is usually used to analyze sound, noise and electromagnetic field. In this research, we propose the wave transmitting boundary by CIP method attached to the 2-dimensional FEM domain. Keywords : CIP Method, FEM, Wave Transmitting Boundary

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