Influence of prestress losses on the dynamic over static capacity ratios of railway concrete sleepers

Railway sleeper, which is placed underneath the rail, is one of the main components of railway track. Railway sleepers can be made of timber, concrete, composite materials etc. Prestressed concrete sleeper is one of the most popular types which can be seen in railway track all over the world. However, loss of prestress is a significant concern as it can affect strength of member and its serviceability including stresses in concrete, cracking etc. In prestressed concrete applications, the most important variable is the prestressing force. It was observed that the prestressing force can be reduced with time because of several factors such as creep and shrinkage of concrete, steel relaxation, friction loss, anchorage slip etc. RESPONSE2000 was used to evaluate the static and dynamic capacities based on the modified compression field theory. The study results exhibit that the losses of prestress have significant effects on the overall strength of prestressed concrete sleepers. It is recommended to take into account the effect of prestress losses in standard design of prestressed concrete sleepers.