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Vol�F10-1Šª
”N�F 1998”N
•Å�F 1193-1198•Å
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Œf�ÚŽGŽ��i‰p�j�F THE EARTHQUAKE ENGINEERING SYMPOSIUM PROCEEDINGS
’˜ŽÒ�i‰p�j�F Makoto KAMIYAMA,Tadashi MATSUKAWA,Masaru,YOSHIDA
ƒ^ƒCƒgƒ‹�i‰p�j�F NON-STATIONARY VARIATION OF SOIL RIGIDITY OBSERVED DURING THE 1995 HYOGOKEN NANBU EARTHQUAKE MAKOTO KAMIYAMA, TADASHI MATSUKAWA, MASARU, YOSHIDA
�´˜^�i‰p�j�F The array-downhole records observed at Port Island during the 1995 Hyogoken Nanbu Earthquake showed a notably non-linear response, suggesting the reduction of rigidity and increase of damping in the soils. Such a non-linear response was confirmed to be not stationary in time. In order to estimate non-stationary variations of rigidity and damping, the complex envelope technique was used together with a finite difference scheme. The method made it clear that the soils near the surface exhibited a remarkably non-stationary variation of rigidity and damping with complicated process of softening and hardening.
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