[2192] NUMERICAL INVESTIGATION ON COMPRESSION FRACTURE LOCALIZATION OF CONCRETE UNDER STEEL TUBE CONFINEMENT
キーワード：compression fracture, localization, nonlinear shell, RBSM, steel-tube confined concrete, 圧縮破壊, 局所化, 鋼管拘束コンクリート, 非線形シェル
The effect of increasing steel ratio and slenderness on the length of compressive localization zone in concrete under steel tube confinement is investigated. The analysis is performed using the newly developed coupled Rigid Body Spring Model and nonlinear shell FEM which represents concrete and steel, respectively, in a steel tube confined concrete member. It was found that the compressive behavior of steel-tube confined concrete is also localized, and the length of localization damage tends to increase with increasing steel ratio. Evaluation of the development of lateral stresses in the steel tube shows that when the confining pressure provided by the steel tube is low, the steel tube is unable to restrain the lateral expansion of concrete, thus localization occurs. However, when sufficient confining pressure is provided by the steel tube, the damage is forced to propagate longitudinally along the length of the member causing a more or less uniform damage.