14.鉄筋コンクリート構造物の耐力に及ぼすコンクリート強度変動の影響

概要

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It is a well known fact that strength of concrete varies significantly at individual parts in a reinforced concrete structure and such a fluctuation evidently affects the load carrying capacity of the structure as a whole. So called allowable unit stress of concrete, therefore, should be understood and determined in this sense from the viewpoint of statistics. Fluctuations of concrete strength in actual buildings have been measured and analyzed by different investigators and many data have been made available. Based on those data of concrete strength fluctuation the author has tried in this paper to find out how the strength of a structure is affected by the fluctuation and what is the true significance of the fluctuation of material strength in the interest of structural engineers. First, the author has analyzed a section of flexural member by assuming Whitney's relationship between concrete strength and ultimate strength of the section, and has found out that the effect of fluctuation of concrete strength is little in this case, rather the effect of strength fluctuation of reinforcing bar being more important. Then, the load carrying capacity of a simple frame has been examined based on Prager's limit analysis theory, and the conclusion has been reached that the effect of concrete strength fluctuation rapidly becomes less important with the increasing number of indeterminacies in the structure.
社団法人日本建築学会の論文
1955-09-30