# Stress Behaviors at Rib-to-Floorbeam Weld and Cutout Details under Controlled Truck Loading
## 2 Field Loading Tests of OSD
### Test Results
#### 2.3.1 Crawl Tests  
A specific test scheme was designed to obtain the stress at the measured details under truck loading. When the data acquisition system was initialized, all records were zero clearing, but the truck was already loaded on the details. Hence, the indicated time histories were not the actual responses of the four details. Hereafter, they are called the gauge records. It can be understood that, after the truck traveled away from the test section, the stress responses at the measured details would be gradually small, and eventually became negligible when the truck was far away from the test section. One can see that when \(t\) is large enough, such as \(t>12\) s in Figure 6, the gauge records were steady and smooth, which means that the truck was already far away from the test section and did not provide any loading effect. With this consideration, gauge records that were steady and smooth were treated as constants to the corresponding gauges. Then, the actual stress records at the four details were obtained by subtracting the constants from the gauge records, as shown in Figure 7. Assuming that the truck was back to the start point, the stress curves were read from right to left, which helps to understand stress responses at different details. Due to limits of space in this paper, strain gauge records at the four details will not be presented any longer hereafter; instead, only the actual stress is provided.  
Figure 6: _Cont._  
LC1 is the over-rib loading on R12. Figure 6 illustrates the stress gauge records at the RF-R, RF-F, RF-W and Cutout details produced by truck crawl running. The truck started to leave floor beam F3 and traveled to the south. For a specific detail, such as the RF-R, the eastern two gauges are symmetrical to the western two along the wheel center, and their  
Figure 6: Strain gauge records under LC1 loading cases. (**a**) RF-R; (**b**) RF-F; (**c**) RF-W; (**d**) Cutout.  
Figure 7: Stress records under LC1 loading cases. (**a**) RF-R; (**b**) RF-F; (**c**) RF-W; (**d**) Cutout.  
curves are expected to be similar if the test arrangement is justified. As shown in Figure 6a, the curves of gauge 2-1 agrees well with 3-1, and 1-1 is close to 4-1, which confirms that the expected wheel location is guaranteed in this loading case.  
Figure 7 plots the actual stress records at the four details under loading case LC1. As shown in Figure 7, gauges 2-1 and 3-1, 2-2 and 3-2, 2-3 and 3-3, as well as 2-4 and 3-4, which are directly underneath the wheel, produced high stresses. Due to their distance to the wheel center larger than one rib spacing, other eight gauges generated low stress. Hence, both the RF and the Cutout details present significant local stress effects to wheel loads. In addition, the stresses at the RF-R, RF-F and Cutout details are compressive, while stress at RF-W is in tension, with a maximum stress range of 13.6, 15.5, 40.8 and 27.5 MPa, respectively. It is clear that the RF-W detail is the most critical detail in the RF connection, and the Cutout detail produced the highest stress range.  
LC2 is the riding-rib-wall loading on the east side of R12, and the actual stress responses at the four details are plotted in Figure 8. As in the case of LC1, the stresses at the RF-R, RF-F and Cutout details are also compressive, while stress at RF-W is in tension, with a maximum stress range of 11.6, 14.5, 42.4 and 29.4 Mpa, respectively. Compared to LC1, the stress ranges at the RF-W and Cutout details increased. As shown in Figure 8, when the detail was close to the wheel center, the stress response at that detail was large, and particularly significant stress response appeared at the detail that was directly underneath the wheel center, such as 2-1, 2