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Analysis of the influence of cracked sleepers under static loading on ballasted railway tracks.

Montalbán Domingo L, Zamorano Martín C, Palenzuela Avilés C, Real Herráiz JI - ScientificWorldJournal (2014)

Bottom Line: Central and rail-seat crack detection require visual inspections, as legislation establishes, and involve sleepers' renewal even though European Normative considers that thicknesses up to 0.5 mm do not imply an inadequate behaviour of the sleepers.The track model considers three different sleeper models: uncracked, cracked at central section, and cracked at rail-seat section.The results show the insignificant influence of the central cracks and the notable effects of the rail-seat cracks regarding deflections and stresses.

View Article: PubMed Central - PubMed

Affiliation: Institute for Multidisciplinary Mathematics, Polytechnic University of Valencia, Camino de Vera s/n, 46022 Valencia, Spain.

ABSTRACT
The principal causes of cracking in prestressed concrete sleepers are the dynamic loads induced by track irregularities and imperfections in the wheel-rail contact and the in-phase and out-of-phase track resonances. The most affected points are the mid-span and rail-seat sections of the sleepers. Central and rail-seat crack detection require visual inspections, as legislation establishes, and involve sleepers' renewal even though European Normative considers that thicknesses up to 0.5 mm do not imply an inadequate behaviour of the sleepers. For a better understanding of the phenomenon, the finite element method constitutes a useful tool to assess the effects of cracking from the point of view of structural behaviour in railway track structures. This paper intends to study how the cracks at central or rail-seat section in prestressed concrete sleepers influence the track behaviour under static loading. The track model considers three different sleeper models: uncracked, cracked at central section, and cracked at rail-seat section. These models were calibrated and validated using the frequencies of vibration of the first three bending modes obtained from an experimental modal analysis. The results show the insignificant influence of the central cracks and the notable effects of the rail-seat cracks regarding deflections and stresses.

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Related in: MedlinePlus

FE of the sleeper cracked at its central section (a) and at rail-seat section (b).
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fig2: FE of the sleeper cracked at its central section (a) and at rail-seat section (b).

Mentions: Once the model of the uncracked sleeper was correctly developed, it was necessary to introduce in the model some modifications in order to simulate the effect of the crack. A crack is a discontinuity in the material that introduces a decrease in the cross section inertia since less part of the concrete section is working. Thus, the cracks weaken the bearing capacity of the sleeper [22]. This decrease in the inertia has associated a decrease in the flexural stiffness. Since the inertia could not be modified because of the geometric characteristics of the model, the same effect was achieved by introducing a decrease of the Young's modulus in the area where the crack appears. That is, the crack was simulated as a volume of more flexible material as observed in Figure 2.


Analysis of the influence of cracked sleepers under static loading on ballasted railway tracks.

Montalbán Domingo L, Zamorano Martín C, Palenzuela Avilés C, Real Herráiz JI - ScientificWorldJournal (2014)

FE of the sleeper cracked at its central section (a) and at rail-seat section (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4228732&req=5

fig2: FE of the sleeper cracked at its central section (a) and at rail-seat section (b).
Mentions: Once the model of the uncracked sleeper was correctly developed, it was necessary to introduce in the model some modifications in order to simulate the effect of the crack. A crack is a discontinuity in the material that introduces a decrease in the cross section inertia since less part of the concrete section is working. Thus, the cracks weaken the bearing capacity of the sleeper [22]. This decrease in the inertia has associated a decrease in the flexural stiffness. Since the inertia could not be modified because of the geometric characteristics of the model, the same effect was achieved by introducing a decrease of the Young's modulus in the area where the crack appears. That is, the crack was simulated as a volume of more flexible material as observed in Figure 2.

Bottom Line: Central and rail-seat crack detection require visual inspections, as legislation establishes, and involve sleepers' renewal even though European Normative considers that thicknesses up to 0.5 mm do not imply an inadequate behaviour of the sleepers.The track model considers three different sleeper models: uncracked, cracked at central section, and cracked at rail-seat section.The results show the insignificant influence of the central cracks and the notable effects of the rail-seat cracks regarding deflections and stresses.

View Article: PubMed Central - PubMed

Affiliation: Institute for Multidisciplinary Mathematics, Polytechnic University of Valencia, Camino de Vera s/n, 46022 Valencia, Spain.

ABSTRACT
The principal causes of cracking in prestressed concrete sleepers are the dynamic loads induced by track irregularities and imperfections in the wheel-rail contact and the in-phase and out-of-phase track resonances. The most affected points are the mid-span and rail-seat sections of the sleepers. Central and rail-seat crack detection require visual inspections, as legislation establishes, and involve sleepers' renewal even though European Normative considers that thicknesses up to 0.5 mm do not imply an inadequate behaviour of the sleepers. For a better understanding of the phenomenon, the finite element method constitutes a useful tool to assess the effects of cracking from the point of view of structural behaviour in railway track structures. This paper intends to study how the cracks at central or rail-seat section in prestressed concrete sleepers influence the track behaviour under static loading. The track model considers three different sleeper models: uncracked, cracked at central section, and cracked at rail-seat section. These models were calibrated and validated using the frequencies of vibration of the first three bending modes obtained from an experimental modal analysis. The results show the insignificant influence of the central cracks and the notable effects of the rail-seat cracks regarding deflections and stresses.

Show MeSH
Related in: MedlinePlus