Experimental study of effects of track systems on static and dynamic behavior of railway bridges

The characteristic exposure of railway bridges to periodic live loads makes an understanding of their dynamic behavior important to their design and construction. This, together with the fact that the behavior of a railway bridge is affected by its track system, has prompted our study of the static and dynamic properties of such bridges. The deflection and stress due to the bending moment were measured, and the location of the neutral axis of each section, the natural frequency, and the damping ratio were analyzed for three systems: girder only, ballast track, and concrete track with various stiffnesses of resilience pad of rail fastening system. Compared to the ballast track, the concrete track extended the location of the neutral axis of the structure by about 6% in the upward direction. Moreover, the dynamic responses of the structure linearly increased with the maximum load and dramatically increased with the load amplitude during resonance. However, the damping ratio was the same with and without a track system. These results confirm the importance of a track system on the essential behavior of railway bridges, especially when a concrete track system is used