Stress Behaviors at Rib-to-Floorbeam Weld and Cutout Details under Controlled Truck Loading

Abstract

The rib-to-floorbeam (RF) connection is the most complicated joint in orthotropic steel decks (OSDs), where four fatigue-prone details are created, i.e., the RF at the rib side (RF-R), RF at the floor beam side (RF-F), RF at the rib wall (RF-W), as well as the floor beam cutout detail. In order to clarify the behavior of those details under the passage of trucks, a controlled truck loading test and finite element analysis (FEA) are performed at various typical transverse loading locations on a newly built long-span cable-stayed bridge. The research finds that, in the bridge transverse direction, stresses at the four details presented significant local effects. Only when these details are underneath the deck plate covered by the wheel patch a notable stress can be produced at these details. In the bridge longitudinal direction, the wheel loading effect at the four details can be discerned only when the wheels load on the deck supported by their adjacent floor beams. The results find that, under wheel loading, the stress ranges at the RF-R, RF-F and Cutout details are compressive, while the stress at the RF-W detail is in tension. The riding-rib-wall loading is the most critical transverse loading location for the RF and Cutout details, and the RF-W is the most critical fatigue detail in the RF connection. The FEA indicates that, due to offset of wheel loads, floor beams may suffer from severe out-of-plane bending, while ribs may experience notable warping and distortion. Under the passage of the tandem axles, the individual axle cannot be identified, and only one stress cycle is produced at the four details.