Strain relaxation analysis of steel-structure heavy-hex high strength bolts

The strain relaxation of heavy-hex high strength bolts in end-plate connections was investigated experimentally using 58 grade 10.9 heavy-hex high strength bolts.The data was fitted by several functions with one recommended for the time variation of the relaxation.The shift method,the sectioning method,and the probabilistic method were used to analyze the high strength bolt strain relaxation for various guaranteed rates.The recommended function predicts the heavy-hex high strength bolt strain relaxation and the probabilistic method is more accurate than the other two methods.