# Impact Evaluation of Track Girder Bearing on Yeongjong Grand Bridge
## 4 Finite Element Analysis  
### Behavior of the Track Girder Bearing  
3D finite element analysis was performed to confirm the structural safety of the vertical and horizontal loads on each form of the bridge bearings. The vertical acceleration acting on the bridge should be within 0.5 g for the bridge decks with concrete tracks, as suggested by the Railway Design Criteria, Eurocode, etc. However, the Yeongjong Grand Bridge has a direct-fixation track and thus, it is not appropriate to apply the allowable vertical acceleration limit for the railway bridge decks with ballast or concrete tracks as presented in the Eurocode or Railway Design Criteria. Therefore, in this study, numerical analysis using field measurement results was performed to verify the adequacy of vibration levels by examining the effect of the vertical acceleration of the direct-fixation track on the structural safety of the supporting point of the track girders. As a result of field measurements,  
Figure 11: Measurement setting for the rail and the track girder: (**a**) view of accelerometer installation; (**b**) accelerometer.  
Figure 12: Comparison of vertical acceleration between the rail and the track.  
the current vertical acceleration of the track was about 1 g or more, which exceeded the standard set in the Eurocode and domestic criteria. Therefore, the structural problems of the support bearing due to the higher vertical acceleration of the track were identified, and the effect of the upward displacement of the support on the structural behavior of the line bearing was analyzed.  
In the case of the line bearing of track girders on the Yeongjong Grand Bridge, it is simply connected with the upper flange of track girders and there is a distance of 10 mm from the upper girder, as shown in Figure 4.  
ANSYS Ver. 17.0 [18] was used as the finite element analysis program, and Solid Edge was used for 3D modeling. Each component of the line bearing model are shown in Figure 13a. Figure 13b shows the ECB component models. Static analysis was performed, and the physical properties are shown in Table 2.  
In order to examine the stability of a bearing by applying a vertical load, all contacts for the vertical load were applied as bonded. The contacts of the bearing were applied as frictional by applying a horizontal load.  
The lower part of the bearing was fixed under supported conditions, and the maximum vertical and horizontal loads were 700 and 210 kN, respectively. To prevent the rotation of the top plate, the x and y displacements were fixed.  
The results of finite element analysis are shown in Figures 14 and 15, and the stresses generated by the members are compared and analyzed in Table 3. In the case of a line bearing, the cross section was small, and the stress of the top plate supported by the line bearing exceeded the yield stress. It was  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Component**} & **Modulus of** & **Poisson’s** & **Tensile Strength** & **Elongation** \\  & **Elasticity (MPa)** & **Ratio (MPa)** & **(MPa)** & **Percentage (\%)** \\ \hline \multirow{3}{*}{ECB} & Central and side cylinders (EP) & 2000 & 0.42 & 70 or more & 15 or more \\ \cline{2-6}  & Steel (SM355 or SCMn2A) & 200,000 & 0.30 & 490 or more & 17 or more \\ \cline{2-6}  & Bolt (10.9 G) & 200,000 & 0.30 & 1040 or more & - \\ \hline \multirow{2}{*}{Line bearing} & 200,000 & 0.30 & 450 or more & 19 or more \\ \hline \hline \end{tabular}
\end{table}
Table 2: Material Properties of ECB and Line Bearing.  
Figure 13: Modeling: (**a**) line bearing; (**b**) ECB.  
found that the safety factor for the common load was not satisfactory. Further, the cross-sectional change caused by the plastic deformation occurred in the top support plate upon exceeding the yield stress. The safety factor for the generated stress of the low plate of the line bearing was estimated to be 5.3 times smaller than that of the ECB.