高力ボルトを用いたスプリットティ接合部の疲労強度に関する研究 : その 3 接合部のボルトの疲労強度推定法

Abstract

An estimation method for fatigue strength of bolt in tee connections is very important as the fundamental data about fatigue design of tee connections. In this paper, the estimation method for fatigue strength of bolt of which bending stress is considered is described. The results of this consideration are followings. (1) Bolt tension versus applied load relationship is estimated by four equations proposed in this paper as bi-linear curve. (2) In high cycle fatigue, the reduction of bolt tension occurs always. The quantity of this reduction has important role in the estimation of fatigue strength and the amount is 7% of the initial clamping force. (3) The method A which considers the bending stress in bolt according to ΔM-ΔF curve is considered. After comparison between estimations and experimental data, it is indicated that this method yields proper estimation of fatigue strength of bolts in tee connections. (4) Considering the results ((1)-(3)), an estimation method B' which yields acurate estimation as the S-N curve is proposed for the fundamental data of fatigue design of tee connections.