Fatigue crack propagation behaviour of the rib–to–diaphragm junction in orthotropic steel bridge deck
Jie Wang, Di Jin, Xiangyu Qiu, Xi Peng, Fengjiang Qin
Abstract
This study investigates the fatigue crack propagation behaviour of rib-to-diaphragm junctions in orthotropic steel bridge decks, with a particular focus on large through-thickness horizontal fatigue cracks at the weld toe of the rib (RTH). A full-scale OSBD test model was subjected to 10 million cycles of constant-amplitude fatigue loading, validating the applicability of ABAQUS and FRANC3D interactive technology for simulating crack propagation, with an error margin of approximately 6.42 %. The fatigue strength of the RTH detail, evaluated using the hot spot stress method, was determined to be 119.7 MPa, representing an improvement of 19.7 % over European standards. Both the crack propagation life and the effective stress intensity factor (Δ K eff ) increase with increasing thickness of the deck, rib, and diaphragm. Notably, increasing the rib thickness from 6 mm to 14 mm resulted in a 64.9 % increase in propagation life and a 54.5 % decrease in Δ K eff . Under actual bridge conditions, fatigue cracks predominantly exhibit Mode I characteristics, whereas Modes II and III are associated with sliding and tearing mechanisms, respectively. Furthermore, a correlation between fatigue vehicle traffic volume and crack length was established. The fatigue crack reaches the deck after 28.03 million vehicle passes, suggesting an estimated service life of 14 years for high-traffic roads and 56 years for medium-traffic roads. These results offer valuable insights into the prediction of crack propagation paths and lifetimes based on traffic volume, thereby supporting the development of effective repair strategies and maintenance scheduling.