Formula for Stiffness of Bolted-Joint Members with Sleeve and Its Applications

In the case of mechanical structures joined by bolts and nuts, many studies have been conducted on the stiffness of the joined members. Accordingly, an approximated formula for this case has already been formulated and verified by experimentation. However, the cased of joined members with a sleeve, which is a common situation in civil engineering, has not yet been considered. Consequently, an elastic closed-form solution is derived for evaluating the stiffness of bolted-joint members with a sleeve, the material of which is different form the joined members. The proposed formula is then verified by an experiment and finite element method. And then it is used to calculate member stiffness in a concrete structure. The results confirm that the proposed formula can be effectively used to calculate the stiffness of joined members with a sleeve, particularly when predicting the fatigue failure of a bolt under fluctuating loads.