Haytham Nour El-Din Zohny

At horizontal railway curves, the track is frequently subject to coinciding vertical and lateral wheel loads, which in some cases could be of high intensity. Currently, the influence of such loading pattern on the centre negative flexural response of prestressed monoblock concrete sleepers (PMCS) is not clearly analysed. As a result, the current codes of practice provide limited guidance pertinent to the design of PMCS under this loading condition. To address these issues, finite element models were accomplished and rigorously verified against analytical and experimental studies existing in the literature. The noteworthiness of the numerical findings, based on the considered loading scenarios, is that the presence of lateral load could increase the flexural stress at the top fibre of midspan sections by 223% compared to the influence of vertical load alone. Based on the numerical outputs, an equation has been proposed to quantify the increased flexural stress of PMCS due to lateral load, and further studies are recommended to complement the results expressed in this research.

The prediction of additional stresses in ballasted track due to subgrade deformation is the main objective of the present paper. In this context, a 2D finite element model of ballasted railway track was built using the ANSYS Workbench program. Based on this model, an investigation of stresses and deformation values of track elements was conducted in three cases with different contact types. It was found that the case introducing the status of a new track, which has frictional contacts between sleepers and ballast with bonded contacts between other elements, has lower stresses in most of the track elements. Moreover, this case was applied for studying the effect of the settlement on track elements. It was found that stresses increased with increasing the settlement value. The average percentages of increased stresses are 4.18%, 5.85%, and 7.21% in railhead, tie plate, and sleeper, respectively, due to a 1 mm increase in the settlement. Finally, a second-degree polynomial equation was derived to predict the additional stresses in each element due to track settlement. It is expected that this study would help to decrease the maintenance costs and extend the service life of the track elements by predicting the additional stresses in them.