Field experiment and FEM validation on fatigue performance of orthotropic steel decks composited with SFRC layer

For small and medium-span bridges using the OSDs, compositing the steel deck with a SFRC layer may provide a cost-effective solution to fatigue induced by repetitively passing trucks. In this study, strain gauges were first instrumented on OSD during the construction of an actual bridge using this composite deck system. Then, two-week continuous stress monitoring under random traffic flows was conducted. The measured stress ranges at those fatigue-prone details are far below the CAFLs of their fatigue categories, implying high resistance against fatigue. To further validate the measured stress behavior, a three-dimensional FEM of the OSD-SFRC composite deck was then established and loaded by the AASHTO fatigue truck. The FEM results also show extremely low stress levels at those measured fatigue-prone details. The SFRC layer significantly enhances deck stiffness and suppresses local stress effects, and hence creates a fatigue-resistant deck system.