Impact capacity of railway prestressed concrete sleepers
Extreme loading conditions on railway tracks may include dynamic impact loads with very high magnitude but short duration. These loading conditions are caused by wheel or rail abnormalities such as flat wheels, dipped rails, etc. This type of loading is very rare and could occur once or twice in their design life span. A high-capacity drop weight impact testing machine was constructed at the University of Wollongong, in order to evaluate the ultimate capacity of prestressed concrete sleepers under impact loads. This paper presents the experimental investigations to evaluate failure modes, flexural toughness, and energy absorption mechanisms for railway prestressed concrete sleepers under static and impact loadings. Energy absorption capacity of the prestressed concrete sleepers was evaluated to determine the amount of energy required to fail the sleeper under impact load. Static and impact tests were carried out on the Australian-manufactured prestressed concrete sleepers. The residual capacity of the prestressed concrete sleepers after impact has also been highlighted. Also, this paper presents a simplified approach to predict ultimate moment capacity of railway prestressed concrete sleepers under impact loading. Modified compression field theory has been employed in the flexural resistance prediction, based on a generalized sectional analysis software, Response-2000. Effects of dynamic strain and loading rates were taken into account for predicting the impact capacity. The test results exhibit very good correlation with the predicted results by the modified compression field theory.