Fatigue Life Prediction of Vulnerable Welded Joints in Q500qENH Weathering Steel Bridge Deck in Low-Temperature Environment

To accurately evaluate the fatigue performance of welded joints in weathering steel bridge decks under the coupling effect of low-temperature environment and multiple vehicle-borne factors， this paper conducted tensile tests and fatigue crack propagation tests on Q500qENH weathering steel specimens under multi-temperature conditions. To verify the test results， corresponding finite element simulations of fatigue crack propagation in the specimens were performed. An orthotropic steel bridge deck finite element model was established to conduct a comparative analysis of the fatigue crack propagation behavior of vulnerable welded joints under multiple constant temperature conditions. Based on this model， the fatigue life prediction of vulnerable welded joints under variable temperature conditions was carried out. The results showed that： the yield strength and tensile strength of Q500qENH weathering steel significantly increased at low temperatures， while the fatigue crack propagation rate significantly decreased； the fatigue life test result fit well with the simulation result， indicating the effectiveness of the test data； the life of vulnerable welded joints decreased with the increase of temperature， the fatigue performance of the top plate weld toe joints was poor， and the longitudinal rib butt joints had a longer fatigue life； low average temperature can effectively delay the crack propagation of the top plate weld toe of the bridge deck and improve the fatigue life.