01.30: Evaluation on clamping load of high strength bolts under ambient environment

Abstract

The torque shear type high strength bolt is clamped in general when pin-tail of shank is cut off. However the clamping loads of high strength bolt did not often meet the required tension due to variation of torque coefficient. This is why the viscosity of lubricant on bolt shank affects the torque coefficient by temperature, dust and debris. In this study, the clamping tests of various high strength bolts were performed independently both at indoor condition and at construction sites for six years. The temperature of construction sites was recorded with the range from -11℃ to 34℃.. The temperature at indoor condition was set up to compose from -10℃ to 50℃ at each 10℃ interval. At construction sites, the clamping load of high strength bolt was varied from 159 to 210 kN and the torque value was varied from 405 to 556 Nm. The torque coefficients at construction sites were analyzed from 0.126 to 0.158 whereas tensions were measured from 179 to 192 kN by using tension meter. The torque coefficients at construction sites were analyzed to range from 0.118 to 0.152. From these tests, the diverse equations on torque coefficient, tension subjected to temperature were taken by statistic regressive analysis.

Weathering Impacts on the Tightening Behaviour of HV/HR‐Bolting Assemblies for Preloading

“…It could be shown that the required tightening torque which is needed to achieve a specific preload level decreases with increasing temperature and that the required preload is achieved with increasing system reserves for a pre-specified tightening torque. Furthermore, investigations regarding temperature influences on the preload of TCBs were carried out by field and laboratory tests [21]. Herein, laboratory test data and data from 24 construction sites were collected over a quality inspection time of five years.…”

Assessment of Different Metal Screw Joint Parameters by Using Multiple Criteria Analysis Methods

“…Izumi and Yokoyama et al [21,22] analyzed relaxation of screw joints with spring washers using the finite element method. In [23][24][25][26][27][28][29][30][31][32], loosening of screws of different types, geometry, and materials, was investigated by considering various clamping forces and temperatures: relaxation rate was related to clamping force. Friction between joint parts were investigated in [31,32] and 2 of 16 connection reliability was related to friction.…”