Performance Evaluation of GFRP Reinforced Railway Sleepers

Verrall, Jacob (2019) Performance Evaluation of GFRP Reinforced Railway Sleepers. [USQ Project]

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Australia’s rail network is an integral part of Australia’s transportation network as 1.3 billion tonnes of freight is moved by rail annually. The majority of Australia’s rail infrastructure remains timber which is susceptible to rot, splitting and insect attack. Recent studies have estimated that 90% of the existing timber sleepers in Australia will deteriorate beyond repair by 2025 meaning they will need to be replaced at an estimated cost of more than $1 billion. To reduce maintenance costs, the rail industry is seeking a more durable alternative than traditional timber sleepers. Composite sleepers have emerged an effective solution but many are still failing before their predicted design life as they are susceptible to cracking and corrosion. This research has designed, manufactured and evaluated the performance of two new composite sleepers using Portland concrete and epoxy based polymer concrete reinforced with glass fibre reinforced polymer (GFRP) bars. These materials have purposely been selected in an attempt to manufacture a more robust and durable sleeper in comparison to timber and other composite sleepers currently available.

To design the GFRP reinforcement, two finite element simulation models based on elastic foundation theory were used to determine maximum bending moment and shear force acting on a sleeper. Once the reinforcement was designed, two test sleepers were manufactured. The polymer concrete sleeper was designed with a traditional concrete core as research highlighted that polymer concrete has a relative low stiffness. Destructive and non-destructive test methods were used to evaluate the performance of these two composite sleepers.

Non-destructive tests proved that both sleepers were able to achieve an acceptable effective modulus of elasticity. By using polymer concrete, the sleeper’s modulus was reduced by 29.44% compared to Portland concrete. This justifies the use of a traditional concrete core to retain an acceptable effective modulus. Stress analysis principles have proven that GFRP bars are a suitable replacement for steel reinforcement. Non-destructive results were also used to predict that both sleepers will fail due to concrete crushing while the GFRP bars will utilised up to 70% of their tensile strength. Destructive testing showed that both sleepers failed due to negative bending moment at the centre, indicating that this behaviour should be carefully considered in the sleeper design. However, minor modifications on the proposed 5-point bending test may be needed to achieve a reasonable ratio of positive-to-negative bending moment and to closely replicate on how the sleeper would be loaded in-track. This theory was proven in Strand 7 as simulations of the test setup indicate that flexural failure first occurred at the middle support which doesn’t align with the failure mode predicted. Although the sleepers failed prematurely, some creditable results were found. One of the most significant findings was that polymer concrete helped to reduce the degree of cracking; the major cause of premature concrete sleeper deterioration. Destructive testing also highlighted that the transverse shear capacity of GFRP bars and deflection might be two limiting design factors.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Manalo, Allan
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 25 Aug 2021 23:56
Last Modified: 27 Jun 2023 04:10

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