Abstract
The high strength bolted joint is one means of connecting structural steel. This method utilizes the high strength of bolts by tightening them high stress and consequently forms rigid joint. Joint strength of the h.s. bolted joint of friction type is determined by taking product of joint member's slip coefficient and bolt clamping force. It has been found that whenever h.s. bolted joint is subjected to heat, there is a reduction of the initial clamping or tension force. The cause of the reduction, however, was not fully explained. In this report, the results of mechanical property tests of the materials used in the relaxation tests of those h.s. bolted joints performed at elevated temperature are reported. These fundamental material properties are used to explain the reduction of initial clamping force in bolts used in h.s. bolted joints subjected to heat. And also the degradation of heat treatment at temperature above the tempering temperature is examined.
