# Load Transfer Efficiency Based on Structural Deflection Assessment of the Precast Floating Track
## 5 Results and Discussion
### Load Case II  
Figure 12 shows the results when the loads were applied to the 2 nd panel at 4/4 loading points (Load case II). The main reason of this Load case is to determine the effectiveness of transferring the load from one panel to another. The loading point was set up at the junction between two panel (2 nd and 3 rd panel). The loads were transmitted between two panel without any dowel bar or connection joint. Figure 11: Comparison of rail relative displacement (Load case I), (**a**) at center point, and (**b**) at end point. Figure 12: _Cont._The previous research about concrete pavement pointed out that at least 10% of initial cost increase if install the dowel bars between the panel [21,22]. To limit that issue, this precast floating slab track used rails to transfer the load from the panels and the distance between each slab was 75 mm. In this type of track, the upper part of the panel was fastened only by the rails, which were separated from the track slab. Because the train runs on these rails, it is necessary to consider the relative deflection of the connected panel. If a difference occurs in the upper part of the panel of the relative deflection of the rail, then the railway train will affect the dynamic behavior, such as the vehicle acceleration, and body acceleration will increase due to a step difference that occurs when the train passes through the connected portion [23]. The vertical deflection of the panel and the rail at the endpoint and the adjacent point were therefore measured. The load transfer characteristics of the slab panel connection can be determined by using load transfer efficiency (LTE), which is defined as by [24]:  
\[\text{LTE}=\frac{\delta_{2}}{\left(\frac{\delta_{1}+\delta_{2}}{2}\right)}= \frac{2\delta_{2}}{\delta_{1}+\delta_{2}} \tag{5}\]  
where, \(\delta_{1}\): is the rail/panel displacement at panel endpoint (mm). \(\delta_{2}\): is the rail/panel displacement at panel adjacent point (mm). Figure 12: Vertical displacement results for three-panel testing (at 2 nd panel 4/4 loading point), (**a**) vertical displacement of the panel (mm), (**b**) vertical displacement of the right rail (mm), and (**c**) rail relative vertical displacement (mm). As shown in Figure 13, the load transfer efficiency (LTE) of this precast floating track was based on the displacement of rail and panel between the loaded panel endpoint (\(\delta_{1}\)) and unloaded panel adjacent point (\(\delta_{2}\)). In this paper, the precast floating track has used the rails mounted on the slabs to transfer the load from one slab to another instead of the connection joint or dowel. If the displacement of loaded slab panel approximated with the unloaded one (\(\delta_{1}\approx\delta_{2}\)), the result in LTE will reach 100% [22]. High stresses will occur if the load transfer is poor and it may cause the pumping, faulting and breaks at the corner. Therefore, load transfer efficiency is especially important to ensure the running safety of floating slab track. The evaluated results are shown in Tables 6 and 7. According to the measurements, when a load of 150 to 440 kN was applied at Load case II, rail deflection was 2.24 to 6.48 mm at the panel's endpoint and was 2.21 to 6.4 mm in the adjacent panel. Meanwhile, the displacement of the panel was 1.31 to 4.68 at the loaded panel and was 1.29 to 4.59 at the adjacent one. However, these values of rail and panel which were calculated by FEA was slightly larger as shown in Figure 14. Based on the 250 kN load of Korea's standardized cargo design load, the rail deflections difference between the ends was 0.08 mm and the panel deflection difference between the ends was 0.06 mm, which was within 2 mm of the Japanese usability standard for high-speed railway bridges. When the track slab separation distance was 75 mm, the inclination of rail was a maximum of 1.2%, which is less than the standard of comfort (2.5 %) as well as the safety standard (2.0%) in Japan.