Abstract
The slip load of high tensile bolted friction joint subjected to high temperature was experimentally investigated. The experiment was composed of two parts. In the first experiment the loading was performed at high temperature and in the second part the loading was done at room temperature, when the specimens had become cool after heating. The heating temperature was 300, 400 and 500℃, and the heating time was one hour. In this experiment three tightening method of bolt were used; grip bolt method, torque control method and turn of nut method. After evaluation of test results, the following conclusions could be drawn. The decrease of slip load is evident, when the high tensile bolted connection is affected by heat over 350℃. The decrease of slip load of heat affected joints is predicted by bilinear line. In case of room temperature loading the slip load does not decrease up to 350℃, but the decrease of the slip load begins at about 350℃ and the slip load becomes zero about at 600℃. In case of high temperature loading the decrease of slip load is about 20-35% more than room temperature loading. As the slip coefficient of the frictional surface (being rusted) is not affected by heating, the main reason of the decrease of the slip load of the heat affected high tensile bolted connection would depend upon the thermal relaxation of bolt tension at high heating condition.
