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2 ボルト軸に生ずる曲げ応力

Abstract

Consideration of bending stress in bolt shank of tee connections is described herin. According to the results from the fatigue tests described in Part 1 and the static tests, the results of consideration about bending stress in bolt shank are followings. (1) When the initial clamping force is introduced into high strength bolt, already the bending moment (M_O) occurs in the bolt shank of tee connections. The average quantity of this moment is 1.27 ton・cm irrespective of the bolt length or the shape of tee connections, and in other words, the amount of the 18.8% of the average stress in bolt shank take place as the bending stress. (2) The bending moment in bolt shank VS. applied load relationship (M-F curve) is affected by the initial bending moment (M_O) and direction of M_O. And so, the shapes of M-F curve are classified into three types in elastic region of bolt shank. (3) Now, it is impossible that the bending moment of bolt shank to any applied load would be estimated by theory. So, according to the results from fatigue tests, the bending moment (M_u) of bolt shank at the upper load in fatigue tests is estimated. The average moment of M_u is 1.26 ton・cm and in other words, the amount of the 18.5% of the average stress in bolt shank occures as the bending stress. (4) The bending moment in bolt shank (⊿M) that results from the range of applied load would be very important to estimate the fatigue strength bolt in tee connections. So herin, the moment (⊿M) is estimated according to the fatigue tests. The fatigue strength of the high strength bolt in tee connections would be estimated by these quantity of bending moment in this paper.