Fatigue properties of orthotropic steel decks with root-deck cracks in the rib-to-deck welded joints at the floor beam intersection

Abstract

Root-deck cracks have been observed from orthotropic steel deck (OSD) bridges under severe traffic conditions. These cracks are primarily caused by the stress concentration due to out-ofplane bending caused by heavy vehicle loads. The quantitative relationship among crack depth, load cycle, and fatigue life remains underexplored due to the difficulty in crack propagation measurement. Fatigue tests were conducted on specimens under varying load ranges to investigate the crack propagation behavior and clarify the fatigue strength of OSDs. Crack depths were estimated from the strain range reduction rate and the fatigue limit state was defined as the load cycle when the crack depth reached approximately 60% of the deck plate thickness. S-N curves were constructed based on effective notch stress.