For the countermeasure technique of fatigue crack on the weld bead between orthotropic steel deck and U-shaped rib, it was proposed to use high-strength stud-bolts as the connection between steel deck and U-shaped rib. In this paper, fatigue strength of high-strength stud-bolt with patch plate under bending was investigated. The high-strength stud-bolt of M20 with the bolt tension of 100kN was used. As the results of bending fatigue test, it was found that the fatigue life of stud-bolt with patch plate is extremely longer than that of the stud-bolt without patch plate. Furthermore, it was revealed the crack depth of specimen with patch plate is lower than that without patch plate.
