A system dynamics to integrate materials science and structural mechanics

(1)为了预测混凝土材料的长期耐久性，本研究对C-S-H凝胶晶体的离子迁移/溶解和分解进行了建模。所提出的材料模型被应用到DuCOM热-湿系统中，该系统涵盖了热量、水分、氯化物、二氧化碳和氧气的传输。此外，还收集了离子迁移的加速实验结果和现场测量数据。(2)通过重建描述胶凝材料水分分布的热力学理论，成功地预测了低水灰比混凝土的连续水化过程。(3)我们建立了一个广义平衡模型，描述了任意粉末材料中自由和束缚态氯化物之间的关系。在含有高炉矿渣的混凝土中，固定为fredel盐的束缚组分不显著，而致密微孔结构带来的吸附组分贡献较大。(4)进行了受ah电路腐蚀的钢筋混凝土梁抗剪性能和受拉加筋试验研究。已经明确，剪切能力取决于腐蚀区域的位置。验证了用分区法和多向裂纹模型可以对腐蚀结构的力学行为进行数值评价。(5)通过对膨胀混凝土弯曲构件和单轴构件的循环加载试验，提出了一个解释膨胀混凝土在拉应力作用下非线性行为的概念。结果表明，化学预应力构件的高抗裂性是由裂缝产生前的高变形能力和预应力引起的抗拉强度的提高带来的。(6)基于修改后的JSCE代码，对Windows环境下的DuCOM系统进行了修改和定制。该软件可以通过给出配合比和环境条件来预测混凝土的材料性能。

(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.