Service life evaluation system for durability of structures at the time of planning and design

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A framework was achieved for the durability in the service life of concrete structures, which is supposed to be carried out at the time of the design and planning before its construction. An evaluation method for initial properties to be achieved in RC structures was developed, in which the factors affecting the properties are construction method, structural details, and material properties and it made possible to evaluate the degree of the influence from each factor quantitatively and to evaluate initial properties of concrete simply. An evaluation method for time-dependent material and structural properties was developed by expanding thermo-hygro analysis system so that the interaction among hydration, micro-pore stricture, and moisture equilibrium can be treated. The concentrations of chloride ion, carbon dioxide, and oxygen were attached to the governing equations in the model and then as much as 100 parameters became included in the element model. It made possible to estimate the time-dependent deterioration of material and structural performance of structure.In the other hand, the model for each factors in durability of concrete structures were also modified as follows : structural behavior of RC member with corroded reinforcing bar, moisture transport in concrete with cracks, hydration rate of concrete with low water to cement ratio, interaction between autogenous- and drying shrinkages, effect of limestone powder on chloride diffusivity in concrete. In addition, fresh properties affecting the long term durability were also investigated. Influence of surface moisture content on the flowability of fresh concrete was investigated. The factors affecting the degree of sinking of coarse aggregate particles into mortar were examined, which affects the uniformity of concrete s composition.