Bending Tests of Pre-Stressed Concrete Rail Sleepers

Sleepers are railway elements subjected to demanding working conditions and strict structural requirements. The acceptance procedures proposed by standard EN 13230-2 for concrete sleepers include the execution of a sequence of static 3-Point Bending Tests. In each step, the maximum applied force is increased by a pre-fixed amount. As a main crack is detected, the corresponding width and residual opening displacement are measured. This kind of testing was performed in previous research work, monitoring fracture propagation by Digital Image Correlation (DIC). This contribution considers a different experimental setup and procedure, consisting of a 4-Point Bending Test with a continuous loading-unloading process. The deformation of the central portion of the sleeper, subjected to uniform bending, and the fracture pattern are monitored by DIC also in this case. The results demonstrate the substantial equivalence of the two alternative approaches compared here for the evaluation of the in-service mechanical performance of these structural elements.