Sensitivity of dynamic responses of railway prestressed concrete sleepers with under sleeper pads to impact energy

In railway track, under sleeper pads (USPs) have recently been adopted as a resilient component placed underneath the concrete sleepers to moderate track stiffness. By the insertion, USPs are generally used to improve railway track resilience in special locations such as turnouts, bridge ends, viaducts, track transitions etc. However, railway tracks usually face high-intensity impact loading due to any imperfection of either wheel or rail. This paper presents a nonlinear 3D finite element model of prestressed concrete sleepers with under sleeper pads in to order to study the effect of USPs under high impact loading. This study has confirmed field studies that the sleepers with USPs tend to have lesser flexures, contact force and impact energy. However, this study reveals that the sleeper with USPs could be amplified by the large amplitude impact energy. These behaviours imply that the applications of USPs should be very careful since the USPs could trade off the desired benefits by aggravating dynamic behaviour of sleepers with under sleeper pads.