Fatigue test study on the joint structure between the deck and longitudinal rib web of orthotropic steel bridge deck

The joint structure between the deck and longitudinal rib web of orthotropic steel bridge deck is liable to have fatigue cracks. Therefore, fatigue tests are carried out on 48 test specimens of 5 groups with different longitudinal rib web and deck thickness as well as manufacturing technology to study the fatigue performance and fatigue design S-N curve of the joint structure. The results show that: when the thickness of longitudinal rib web is 8 mm and deck thickness is 12 mm, shear failure will occur along the thickness direction of the deck and fatigue performance is poor; when the deck thickness is increased from 14 to 16 mm, the fatigue performances of test specimens have been somewhat improved; when the deck thickness is increased from 16 to 18 mm, the thickness of longitudinal rib web is increased from 8 to 9 mm, the fatigue performances of test specimens have hardly changed; the fatigue performances of test specimens have not been improved at all by bilateral penetration welding, instead, slightly lower than 75% unilateral penetration welding. S-N curve regression analysis on the fatigue test data of joint structure shows that the joint structure can be classified into IX category in code for design of steel structures in railway bridge. When failure cycle is 2×106, the stress amplitude is 71.9 MPa.