Abstract
The rail and track girder of the direct fixation track (DFT) system on the Yeongjong Grand Bridge (YGB) in Korea exhibit integrated behavior. Therefore, unlike the DFT system in general concrete tracks, the track support stiffness (TSS) of the DFT system on the YGB cannot be evaluated with only the displacement of the rail. The actual TSS of the DFT system supported by the flexible track girders was lower than that of the DFT system supported by the general substructure. For this reason, field measurements and a finite element analysis that reflects the actual operating speed of railroad vehicles on the YGB (i.e., Airport Railroad Express (AREX), nonstop Airport Railroad Express (AREX Express), and Korea Train Express (KTX)) were conducted in this study to determine the interactions between the rail and the track girder. The results indicated that the DFT system on the YGB is supported by track girders that exhibit relatively flexible behavior. As a result, the TSS is directly influenced by the bending stiffness of the track girder.
Highlights
Numerous studies have been conducted on the rail support. e dynamic response to rail support was studied by researchers by performing the theoretical study and the finite element analysis (FEA) [1,2,3,4,5,6]. e dynamic response of a track is not affected by dynamic properties of the train other than its unsprung mass
E results shown in Figures 4(g) and 4(h) indicate that the changes in the dynamic wheel load and rail vertical displacement according to the change in the speed of each train are not very significant. erefore, the dynamic response of the direct fixation track (DFT) is not directly influenced by the velocity of the trains if they are running within the operational velocity
Results and Analysis. e results of the analysis and measurements show that the analyzed and measured vertical displacements of the track girder in Figure 6(b) were similar, indicating that the DFT supported by track girders has a similar deflection for both the rail and track girder (Figures 4(h) and 4(i)). erefore, the track support stiffness (TSS) of the DFT placed on top of the relatively flexible track girder is directly influenced by the bending stiffness of the track girder and the deflection that has the same position. erefore, the analytical displacement of the track girder calculated on the basis of the numerical analysis model was compared with the measured displacement
Summary
Numerous studies have been conducted on the rail support. e dynamic response to rail support was studied by researchers by performing the theoretical study and the finite element analysis (FEA) [1,2,3,4,5,6]. e dynamic response of a track is not affected by dynamic properties of the train other than its unsprung mass. The rail support responses are investigated by performing field measurements and numerical analysis with track support stiffness of the direct fixation track on the railway bridge. E track system on the Yeongjong Grand Bridge (YGB) is a direct fixation track (DFT) attached to a long-span special bridge (cable and truss), and its concept originated from the track style of the Great Seto Bridge in Japan [7]. Such a track type is the only special case in Korea, which leads to the lack of studies far [7]. Owing to its bending behavior, the bending stiffness of the track girder must be accounted for in the calculation in order to evaluate the actual TSS of the DFT on the YGB. erefore, by performing field measurements of the tracks and considering the operational velocity of the trains that run on the DFT of the YGB (i.e., Airport Railroad Express (AREX), nonstop Airport Railroad Express (AREX Express), and Korea Train Express (KTX)), the actual TSS of the DFT was evaluated in this study
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