Performance of Prestressed Concrete Sleepers under Static Loading
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Date
2021-10
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Addis Ababa University
Abstract
Railway pre-stressed concrete sleepers are an integral part of the railway track as they hold and move the wheel loads from the rails to the track foundation. Prestressed concrete sleepers are subjected to various types of static load condition after a certain time, which can lead to some reduction in the effective behaviour of sleepers. Consequently, in order to preserve efficiency and to prevent the deg-radation of the railway system, it is important to consider various conditions of support during the design of the railway sleepers. The objective of this research was to study the load-carrying capacity of the prestressed concrete sleepers where Polybeam and BOEF were used for flexural analysis and a Finite element package ABAQUS was used to analyse the static loading response on prestressed concrete sleepers considering elastic support. From flexural analysis, at the rail seat the results have shown that the maximum bending from Polybeam and maximum bending moment from BOEF the percentage difference is 0.19% and at the center of the sleeper the maximum bending moment from BOEF and maximum bending moment from Polybeam the percentage difference is 5.12%. The max-imum shear force at rail seat the results have shown that maximum shear force from BOEF and max-imum shear force from Polybeam are similar because the percentage difference is 0.01%.For deflec-tions for rail seat and at the center of the sleeper the results have shown that the percentage differ-ence is 4.9% and 5.47% respectively. Therefore there is a small portion of difference between re-sults from Polybeam and BOEF.From static modeling, the possible favorable and unfavorable elastic support circumstances have been analyzed. With a lot of variance in ballast rigidity and very soft support underneath the center of the sleeper and along the length of the sleeper, for all circumstances the results show that the displacements and stresses are significant on the rail seat and it has shown that onceballast stiffness reduce at the centre of the sleeper from 100% to 90%,80%.70%,60%,50%,40%.30%, 20%, and 10% supported , the displacement of the sleeper in-creased a small portion of (0.004%-0.091%) more than 100% supported and stresses in-creased(0.027%-0.07%) more than 100% supported. Therefore, once the ballast stiffness reduces at the center of the sleeper there is a small increase in displacement and stresses but to keep the perfor-mance of the sleeper, the low ballast stiffness at the center of the sleeper should be avoided. once the ballast stiffness reduce along the sleeper from 100% supported (full supported) to 90% , 80%, 70%, 60%,50% and 25% supported , the displacement increased with 3.27%, 7.29%, 12.37%, 18.97%, 27.94% and 76.7% respectively more than full supported and von mises stresses increased 0.28%, 0.86%, 1.06%, 1.062%, 3.12% and 12.04% respectively more than 100% supported . Therefore, when there is high ballast stiffness reduction along the sleeper, there is more increasing in displace-ment. Because it is impossible to predict the exact support distribution, it is of importance for sleeper designers and manufacturers to evaluate the influence of variations in ballast stiffness and distribu-tion
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Keywords
prestressed concrete sleepers, static loading, elastic full support, partial support, Abaqus