This paper presents an investigation on pre-stressed concrete sleepers based on the principles of fracture mechanics in concrete material. To evaluate fracture mechanics parameters pre-stressed concrete sleepers with different initiation crack length varying between 0 mm and 45 mm increasing by 5 mm steps are used. A three-point bending loading condition is considered. Finite element software is employed to model the sleepers and to calculate the parameters of fracture mechanics such as and crack growth. Finally, in this study for validation, load-displacement diagram of 5 experimental samples is compared with numerical model of finite elements for validation of model. The paper shows that an expansion in crack instability follows from increasing crack-to-depth ratio, initial toughness, the crack stability and crack unstable toughness, the crack instability expansion begins. The paper also shows a good agreement between the numerical and experimental results via comparing the results of the 5 samples with the numerical model.
