# Fatigue Performance of Different Rib-To-Deck Connections Using Traction Structural Stress Method
## 3 Fatigue Performance of Rib-To-Deck Connection Types in Orthotropic Steel Bridges
### The Law of Traction Structural Stress of Geometric Parameters of the Rib-To-Deck  
Figure 19 shows the Mises stress distribution of the connection of rib-to-deck, and Figure 20 gives the von [PERSON] stress distribution and fatigue cyclic lives distribution trend of the bottom side of the bridge deck. The Mises stress at the middle of the connection was more significant than that at other locations, and the stress decreased along the weld seam. The stress at the weld root was more significant than that at the weld toe, and the minimum cyclic life was obtained in the middle of weld root. Various stresses, including the Mises stress (Mises), stress intensity (s_int), principal stresses (S1-3) and equivalent structural stress (SS), were determined as the evaluation indices. In the stress distribution contours shown in Figure 21, Figure 22, Figure 23, Figure 24, the left coordinate axis represents the value of the Mises stress (Mises), stress intensity (s_int) and equivalent structural stress (SS). The right coordinate axis stands for the value of the principal stresses (S1-3). Weldline1 represents the weld toe of the weld seam and Weldline2 stands for the weld root of the weld seam. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Size** & **Parameter** & **Parameter Range** \\ \hline Deck plate size & \(600\times 400\times 18\) & Circle radius & 5–25 mm \\ U-shaped rib size & \(300\times 200\times 180\times 8\times 400\) & Groove angle & 20–65\({}^{\circ}\) \\ Crossbeam size & \(600\times 340\times 10\) & Deck thickness & 12–24 mm \\ Weld type & Groove weld & U-shaped rib thickness & 6–16 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Overall schemes and geometric parameters of OSBD. Figure 19: Mises stress distribution of the rib-to-deck connection. Figure 18: The constraint, fatigue load and component of the OSB in the partial model. Figure 21 shows the trends of various stresses with the groove angle. The Mises stress, stress intensity, principle stress and the equivalent structural stress of Weldline1 and Weldline2 are calculated and plotted as the contours. The comparative contours show that the Mises stress, stress intensity and equivalent structural stress of Weldline1 were small and decreased slightly with an increase in the groove angle. The trends of Mises stress and stress intensity of Weldline2 were similar. The Mises stress, equivalent structural stress and stress intensity of Weldline2 decreased with an increase in the angle. The principal stresses of Weldline2 remained constant with an increase in the groove angle. Figure 22 shows the trends of various stresses with the radius of the weld seam. The results indicate that the Mises stress, stress intensity and equivalent structural stress of Weldline1 were relatively small and decreased sharply with an increase in the radius. The trends of Mises stress and stress intensity were similar. The Mises stress, equivalent structural stress and stress intensity decreased with an increase in the radius. The principal stresses decreased with an increase in the radius. In addition, the third principal stress (S3) of Weldline2 decreased sharply by 32.6% with an increase in the radius from 5 mm to 25 mm. Figure 20: Mises stress distribution and cyclic life distribution of the deck plate. (**a**) Distribution contour of the Mises stress at the bottom side of the bridge deck (Pa). (**b**) Distribution of the fatigue cyclic life of the rib-to-deck connection, 1 the number in the contours is the base 10 log of the contour line. similar. The Mises stress, equivalent structural stress and stress intensity decreased by approximately 55% with an increase in the bridge deck thickness. The principal stresses of Weldline1 and Weldline2 decreased slightly with an increase in the bridge deck thickness.