抄録
Deterioration of the structural bearing force is generally caused by corrosion of the structural materials except in the case of earthquacke or typhoon. When we discuss and make out preservative counteraction against the damage to the building, we must make clear the corrosion speed. In the first part of this report I have shown the general equation between the loss in thickness of steel and time according to the electrochemistry theory, and the practical equation (1) considering various elements, which are composition of the steel (n), local conditions of the building lot (α), conditions of construction method (β), and effect of the anticorrosive treatment (γ). [table] On the next step we must gain the values of α, β and γ from many investigations of building and experiments of steel corrosion. I have shown these values which were obtained by the experiments carried in the chemical plant and the other districts. Clearing the values of coefficients shown as equation (1) we can presume the life of the building according to the equation (2). [table] In the second part of this report I have shown the preservative schemes based upon the economic ground. Ordinally the cost of the building to which some preservative methods are given is higher than the cost in the case of non-treatment, but the life is extended. Therefore the preservative method given on the building should be determined by comparison of economical benefit considering the cost and the life of the building. In the method of economical comparison I chose the idea of capitalized cost, and using this idea I have stated in this report the selective method of structural materials, the method of structural calculations and the selective method of anticorrosive treatment. Accordingly this report has pointed that we can presume the life of the building and choose the preservative scheme which gives economical benefit to the building.
