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

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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.