# Stress Behaviors at Rib-to-Floorbeam Weld and Cutout Details under Controlled Truck Loading
## 2 Field Loading Tests of OSD
### Test Results
#### 2.3.2 Dynamic Test  
As indicated in the crawl tests, the riding-rib-wall loading is the most critical transverse loading location for the RF and Cutout details. Hence, the loading case of LC8, with the wheel centered exactly at the same location as LC2, was employed in the dynamic test. The truck traveled with a speed of about 40 km/h, and the data were sampled with a frequency of 100 Hz.  
The dynamic stress at the four details under LC8 is plotted in Figure 12. Since the transverse loading location is the same as LC2, the results from the two loading cases are comparable. In the crawl tests, the rear axle was initially centered on the floor beam and then moved away from it. Hence, one can compare their stresses produced by the rear axle. The curves after the stress peaks or valleys in Figure 8 share almost the same trends with those in Figure 12. In the dynamic test, stresses at the RF-R, RF-F and Cutout details are in compression, while the RF-W detail is in tension, with maximum stress ranges of 14.5, 11.8, 41.7 and 33.5 MPa, respectively. Those values agree well with the results of the crawl test. In addition, the four details on the east side of R11 presented very small stress responses. It is again confirmed that if, the details are not underneath the deck plate covered by the tire width, their stress responses will be small.  
Figure 12b shows the stress peaks of 2-2 with the marked truck axles. Having the time interval that took the truck axles to pass on the same detail, the truck speed can be estimated. In Figure 12b, considering \(t_{0}\) = 0.29 s, \(t_{1}\) = 0.56 s, \(t_{2}\) = 0.90 s, \(t_{3}\) = 1.01 s and \(t_{4}\) = 1.27 s, the calculated truck speed, based on the front and rear axle, is 41.6 km/h, which is close to the expected speed of 40 km/h.  
Figure 12: Stress records of the four details under the passage of the truck with intermediate speed. (**a**) RF-R; (**b**) RF-F; (**c**) RF-W; (**d**) Cutout.  
The stress influence line of the four details in the bridge longitudinal direction can be estimated. Based on the truck speed of 41.6 km/h, \(t_{0}\) and \(t_{1}\) as shown in Figure 12b, the calculated length of the stress influence line produced by the front axle at the RF-F detail ahead of the peak stress is about 3.0 m, which means that only when the front axle crossed the adjacent floor beam and approached the tested floor beam, gradual apparent stress can then be observed at this detail. Considering the stress generated by the rear axle, the instant corresponding to its peak stress in Figure 12b is \(t_{3}\) = 1.01 s, and its negligible loading effect starts from \(t_{4}\) = 1.27 s. Consequently, the estimated length of the stress influence line after the stress peak is around 3.0 m, which means that only when the rear axle moved across the floor beam ahead of the test floor beam, the wheel loading effect at this detail is small and negligible. Accordingly, for the RF-R, RF-F, RF-W and Cutout details on the specific floor beam, their wheel loading effects are limited between their adjacent floor beams. In other words, if the wheel loads outside this area, its loading effects can be negligible. Hence, the length of the stress influence line for this bridge is 6 m.