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Deterioration mechanisms and life cycle of concrete monoblock railway sleepers in Finnish conditions

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

Details

Original languageEnglish
Title of host publicationWCRR 2016 Proceedings
Subtitle of host publication11th World congress on railway research, 29.5-2.6.2016, Milano
Publication statusPublished - 31 May 2016
Publication typeD3 Professional conference proceedings
EventWORLD CONGRESS ON RAILWAY RESEARCH -
Duration: 1 Jan 1900 → …

Conference

ConferenceWORLD CONGRESS ON RAILWAY RESEARCH
Period1/01/00 → …

Abstract

Thirty eight sleepers aged 30 to 40 years old were removed from Finnish railway lines and were loaded. Twelve new sleepers were also tested. The old sleepers fulfilled most of the requirements specified for the new ones. The old sleepers were also much more resistant to loading than predicted by structural calculations. The purpose of field tests was to establish the role of traffic loads in the life-cycle of sleepers: the actual stresses and moments in sleepers due to traffic loads; the distribution of the load through the underside of the sleeper to the ballast; and the variation in ballast-sleeper reaction on different sections of track in different seasons. Strain changes at the top surfaces of sleepers were measured on tracks while the rail was loaded by passing trains. Ballast-sleeper reactions tended to be concentrated under the rail along a length of sleeper of approximately 350 mm towards the centre of the track. The mean bending moments determined at the rail seat and centre of sleepers were about ±2.5 kNm, and the maximum moments were up to ±10 kNm. The purpose of fatigue loading tests was to analyse the long term properties of the sleepers and the effect of fatigue on the stiffness of sleepers. Several load levels were chosen in order to estimate the significance of the fatigue in a real operating situation. The fatigue limit determined based on the loading tests and the computational limit state of crack formation were clearly higher than the bending moments measured in the field tests.