ファジィ理論のＲＣ床版の疲労解析への応用

Abstract

Recently, fatigue failure has become frequent in RC (Reinforced Concrete) decks of urban expressway bridges, because of the increase of heavy vehicle transit and the deterioration of the structure itself. In a usual fatigue analysis of mechanical components and systems, their fatigue lives are estimated by using the simple law of cumulative damage. This law is based on the relation between the load intensity and its repeated cycles until failure. This relation is presented in the form of a so-called S-N curve which is determined from experiments. To obtain a reliable S-N curve, a great deal of experimental data should be collected. However, it is difficult to conduct a sufficient number of fatigue experiments on RC bridge decks, due mainly to the financial and technical restrictions.In this paper, an attempt was made to apply the fuzzy sets theory to the fatigue analysis of RC bridge decks. The S-N curve was modeled through the fuzzy regression theory instead of using probabilistic concepts. This was because the concept of frequency is useless in case of having few data, i.e., about ten samples. By using the fuzzy regression analysis, it was possible to develop a possibility model to draw up an S-N curve and to estimate the fatigue life of RC bridge deck in a more realistic and significant manner.