# Stress Behaviors at Rib-to-Floorbeam Weld and Cutout Details under Controlled Truck Loading
## 2 Field Loading Tests of OSD
### Test Results
#### 4.2.2.2 _Appl. Sci._**2022**, 12, 3012  
In this loading case, the wheel was centered between R12 and R13. The stress at the RF-R detail was the lowest, as shown in Figure 9. The maximum stress ranges at the RF-R, RF-F, RF-W and Cutout details were, respectively, 9.3, 16.9, 26.7 and 41.1 MPa. Compared to LC1 and LC2, it is clear that the LC2, i.e., the riding-rib-wall loading, is the most critical loading location for the RF-W and Cutout details.  
The wheel loads produced a high stress at those details directly underneath the wheel, such as the gauges on the west side of R13 and those on the east side of R12. For the details at the west side of R12, their stresses decreased. The stresses at the four details around R11 are very low and clearly negligible. This may also be due to the fact that their distances to the wheel center are larger than one rib spacing.  
Considering the load distribution function of the 70 mm asphalt overlay on the bridge deck, as well as a load dispersal angle of 45\({}^{\circ}\) to the vertical, the tire dispersal scale in the bridge transverse and longitudinal direction increases, respectively, to 640 mm and 340 mm on deck plate top surface, as shown in Figure 10. It should be noted that 640 mm on deck plate surface is wider than the center-to-center rib spacing.  
With this consideration, based on the stress shown in Figures 7-9, one can find that, if the gauges were underneath the deck plate covered by the tire width, the stress responses at these gauges would be significant. If the gauges were not underneath the deck plate covered by the tire width, its stress response would be small or even negligible.  
It is important to consider the stress responses at the four details under various transverse loading locations, with \(x\) defined as the distance from the wheel center from LC2 to the other loading cases and the eastern side being defined as a positive direction.  
Figure 9: Stress records under LC3. (**a**) RF-R; (**b**) RF-F; (**c**) RF-W; (**d**) Cutout.  
Figure 11 plots the peak stresses measured at the four details at the east side of R12, i.e., 2-1, 2-2, 2-3 and 2-4, under the seven loading cases in the crawl tests. For the apparent stresses at these gauges, it is clear that the stress level at the RF-W and Cutout details is notable higher than that at the RF-R and RF-F details. Hence, more attention should be paid to the RF-W detail based on its relatively low fatigue category. In addition, the riding-rib-wall loading is the most critical transverse loading location among the three typical loading cases.  
As shown in Figure 11, when the details are directly underneath the wheel (\(x=-0.15\), 0 and 0.15 m), high peak stresses appear, and if the details are underneath the deck plate covered by the tire width (\(x<0.365\) m), apparent stresses can still be measured. However, if the details are underneath the deck plate that is not covered by the tire width (\(x\geq 0.6\) m), their stresses are very small. This again confirms that, in the bridge transverse direction, the stresses at the RF-R, RF-F, RF-W and Cutout details present a significant local stress effect under wheel loading.  
Based on the above consideration, for a passing truck, the stresses at the RF and Cutout details generated by one side of the wheel would not be superimposed with those from another side. Particularly, the loading effects on the RF and Cutout details produced by multiple trucks traveling side-by-side in different lanes can be ignored. This consideration greatly simplifies fatigue truck loads in the FEA of OSDs and facilitates the stress analysis regarding various transverse and longitudinal loading locations.  
Figure 11: Peak stress at 2-1–2-4 versus distance to wheel center.  
Figure 10: Tire dispersal width in bridge transverse direction. (Unit: mm).