A system dynamics to integrate materials science and structural mechanics

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(1) In order to predict long-term durability performances of concrete materials, ion migration/dissolution and decomposition of C-S-H gel crystals were modeled in this study. The proposed material model were implemented into DuCOM thermo-hygro system, which covers heat, moisture, chlorides, carbon dioxide, and oxygen transport. In addition, the accelerated experimental results on ion migration and in-situ measurement data were gathered.(2) By reconstructing the thermodynamics theory describing moisture profile in cementitious materials, it has been succeeded to predict continuous hydration process of low water-to-cement ratio concrete.(3) We developed a generalized equilibrium model presenting the relationship between free and bound chiorides for arbitrary powder materials. In case of concrete containing blast furnace slag, the bound component fixed as Freedel's salt is riot significant, but the contribution of adsorbed component brought by dense micro-pore structure is relatively large.(4) A experimental study on shear behavior and tension stiffening of RC beam corroded by ah electric circuit was carried out. It has been cleared that shear capacity depends on the location of corrosion area. We verified that mechanical behavior of corroded structure can be numerically evaluated by the zoning method and the multi directional crack model.(5) Through cyclic loading test for bending and uni-axial members of expansive concrete, we proposed a concept to explain nonlinear behavior of expansive concrete under tensile stress. It was shown that high crack resistance of chemical prestressed member was brought by high deformability before the generation of crack as well as the increase of tensile strength due to prestressing.(6) Based on the revised JSCE code, DuCOM system was modified and customized for Windows environment. This software can predict material properties of concrete by giving mix proportions and environmental conditions.