GFRP-Reinforced Concrete Guideway Beams for Monorail Applications

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Wootton, Nikolaus
Field Study , Fibre Reinforced Polymer , Reinforced Concrete , Structural Analysis , Transit Infrastructure
Increased demand for reliable public transit is motivating new and innovative transportation solutions. Monorail trains are quickly being established as transportation solutions for dense urban areas, due to their unobtrusive infrastructure. To obtain maximum value from investments made, the infrastructure is required to last longer than typical reinforced concrete. This thesis will explore the use of glass-fibre reinforced polymer (GFRP) bars as reinforcement in concrete guideway beams as a means of avoiding the deterioration problems that plague steel-reinforced concrete. This thesis includes a two part investigation: a full-scale field application of a GFRP-reinforced concrete guideway beam (690 mm x 1,500 mm x 11,600 mm), compared to a typical steel-reinforced beam (both installed on a 1.86 km long monorail test track); and a laboratory study of a scaled-down version of the GFRP-reinforced beam to better predict behaviour beyond typical service load levels. A total of 450 test passes of a two-car monorail train were observed over the two instrumented beams on the track. These passes were performed at vehicle loads ranging from fully unloaded for the first testing phase, up to the maximum allowable design service load. At each stage of testing, vehicle speeds ranged from as low as 5 km/h to as high as 90 km/h, allowing for the dynamic behaviour of the guideway to be observed and quantified. Deflections, strains, and cracks were recorded and compared with code/guideline limitations as well as to numerical predictions to determine which design tools were most effective and could predict behaviour accurately. In the laboratory, the half-scale GFRP-reinforced beam was tested statically to failure, and the behaviour was compared to the same modelling tools used in the field study. Based on the testing performed, the GFRP-reinforced concrete beams performed satisfactorily and met all serviceability requirements, but did not perform as well as the steel-reinforced beam (as a result of the reduced stiffness of GFRP). The use of non-prestressed GFRP-reinforced beams should be limited to applications where spans are of comparable length to the field study. To maintain satisfactory performance, guideway spans significantly longer will need to continue to be design as prestressed beams.
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