Unification of thermo-physics of materials and mechanics of concrete structures

在本研究中，材料和结构的力学和热力学的统一是为了同时评估混凝土结构的整体结构和材料的寿命性能。本研究的结果可以总结如下。(1)提出了三维有限元、结构分析程序和三维有限元热湿物理分析的集成计算系统。这种多任务操作下的耦合方法，使得工程师即使编写不同的语言和算法，也可以很容易地将独立开发的计算机代码链接起来，因为每个系统都由操作系统管理，计算结果可以通过公共数据区共享。(2)在上述体系中，应评价胶凝材料因受潮、水化、传热而产生的体积变化。在本研究中，我们提出了一个基于微力学物理的自干燥收缩模型。从毛细张力和微孔结构的发展两方面模拟了收缩行为。该框架可以作为预测混凝土体积变化的一种方法，这种变化是由于混凝土的自收缩、干燥收缩以及它们在任意条件下的组合。(3)提出了一种基于微物理信息的凝固模型，用于预测硬化混凝土的徐变和收缩。骨料被理想化为具有完美弹性的悬浮连续介质，而水泥浆被视为具有各种力学性能的固化团块。用两相的组合来表示早期不稳定瞬态情况下的整体复合材料。在这个框架中，基本蠕变、干燥蠕变和无约束收缩行为可以统一地进行评估，而无需区分每种现象。

In this research, the unification of mechanics and thermo-dynamics of materials and structures is tackled for simultaneous evaluation of the total structural and material performances over the life span of concrete structures. The results of this research can be summarized as follows.(1) An integrated computational system of 3D FE, structural analysis program, and 3D FE thermo-hygro physical analysis was proposed. This coupling method under multi-task operation enables engineers easily to iink independently developed computer codes even if being written different languages and algorithms, since each system is managed by operating system and the calculated results can be shared through the common data area.(2) in the above system, the volume change of cementitious materials due to moisture, hydration, and heat transfer should be evaluated. In this study, we proposed an autogenous and drying shrinkage model based on micro mechanical physics. The shrinkage behavior is modeled from the capillary tension force and the development of micro-pore structure. This framework can be a predictive method of the volume change of concrete due to the autogenous, drying shrinkage and their combination for arbitrary conditions.(3) A solidification model based on microphysical information for the prediction of both creep and shrinkage of hardening young concrete is proposed. Aggregates are idealized as suspended continuum media of perfect elasticity, whereas cement paste is treated as the solidified clusters having each mechanical property. The combination of both phases is used to represent the overall composite under unstable transient situations at early age. In this framework, basic creep, drying creep, and unrestrained shrinkage behavior can be evaluated in a unified manner without distinguishing each phenomena.