# Stress Behaviors at Rib-to-Floorbeam Weld and Cutout Details under Controlled Truck Loading
## 3 FEA of OSD Panel Model under Wheel Loading
### FEA Results and Discussion
For the same details, stresses at the details underneath the deck plate covered by the tire width are significantly higher than those that are not covered by the tire width, as displayed in Figure 18. Under the passage of the tandem axles, the highest stress response appears at the Cutout detail, followed by the RF-W detail. The maximum stress ranges at the RF-R, RF-F, RF-W and Cutout details are 14.7, 9.7, 33.1 and 37.8 MPa, respectively, which agrees well with the results of the crawl tests. Compared to the crawl tests, the stress curves after the passage of the rear axle in Figure 9 also agree well with those in Figure 18.  
For the three typical transverse loading cases, the results also indicate that the riding-rib-wall loading is the most critical transverse loading location, which produces the largest stress ranges at the four details. Meanwhile, stresses at the RF-R and RF-F details are relatively low, but high stresses are produced at the RF-W and Cutout details. Although the stress at the Cutout detail is the highest, which is only slightly higher than that at the RF-W detail, the Cutout detail accounts for the highest fatigue category (Category A) and the RF detail is in Category C, with constant-amplitude fatigue limits of 165 MPa and 69 Mpa, respectively [30]. As a result, the RF-W detail is the most critical detail in the RF connection, where more attention should be focused. Additionally, based on the relationship between the fatigue life and cubic stress range at the fatigue detail per AASHTO LRFD [30], under the passage of the tandem axles, only one stress cycle is produced at the four details. This may be due to the fact that the four details are relatively far away from the wheel loads. Figure 19 plots the von Mises stress contours and deformation of F3 and R12 when the middle axle loads on this floor beam, under the three typical transverse loading locations. Apparently, a significant stress concentration appears at the RF and Cutout details. Considering the deformation of the ribs at their intersection with the floor beams, as shown in Figure 19, the ribs undergo a complex deformation, such as rib distortion, which is highly dependent on its location with respect to the wheel loads. For the over-rib loading shown in Figure 19a, since the wheel centers on R12, a low portion of the rib undergoes apparent widening. The RF-W detail suffers from outward bending, and hence tensile stress is produced at this detail. The over-rib loading on R12 is an eccentric loading to the nearby R11 and R13, which produces notable torsional moment, and hence a significant distortion appears on the nearby ribs, which results in a warping deformation at the rib wall low portion. Consequently, a high tensile stress is created at the RF-W detail due to the constraint from the floor beam at their intersection. In addition, for LC2 and LC3, the wheel load is also eccentric to both R12 and R13, and hence a significant distortion and high stress appear at the RF-W detail. This explains why a high tensile stress appears at the RF-W detail under controlled truck loading.