Investigations of static and dynamic performance of railway prestressed concrete sleepers

摘要

Ever increasing axle loads and train speeds are pressing track owners to extract as much performance as possible from their asset without wholesale or catastrophic failure. Unfortunately, there is insufficient knowledge of the static and dynamic loadings that a track may be subjected to in its lifetime, and there is widespread suspicion that track components have reserves of strength that are untapped, especially concrete sleepers. Addressing these issues has the potential for substantial savings for track owners. It's important therefore to ascertain the spectrum and amplitudes of forces applied to tracks, to understand more clearly the manner in which track components respond to those forces, and to clarify the processes whereby concrete sleepers in particular carry those actions. In this paper the load-carrying capacity of the selected Australian prestressed concrete sleepers is investigated under static and dynamic loading conditions. The sleepers are subjected to impact loading using a large capacity drop hammer to simulate the repeated impacts due to wheel flats or engine burns. These repeated impacts could eventually lead to cracking and failure of the sleepers, and hence are important in the context of developing the limit state design approach for the concrete sleepers. Using the impact loading technique, such phenomena as impact damage and residual strain, as well as the fracture energy as a performance indicator of damage for the selected limit states, are also quantitatively evaluated.