Design and Development of Glass-Fibre-Reinforced Polymer and Ultra-High-Performance Fibre-Reinforced Concrete Guideway Girder

An innovative design for prefabricated rail guideway girders is developed and validated. The proposed concept uses compositely acting glass-fibre-reinforced polymer (GFRP) and ultra-high-performance fibre-reinforced concrete (UHPFRC), achieving a girder that is 30% lighter than state-of-the-art prestressed concrete designs. Questions regarding the structural behaviour of compositely acting GFRP--UHPFRC are addressed through prototyping and experimental studies. A robust structural connector for GFRP--UHPFRC, which can be fabricated during the same vacuum infusion process that produces the GFRP shell, is developed and tested. The tensile fatigue behaviour of UHPFRC is characterized through a series of direct tension cyclic tests, showing that for peak cyclic tensile stress below 7.5MPa, there is no progressive damage to the UHPFRC. The intrinsic damping of UHPFRC is investigated through a series of free-vibration tests, demonstrating that a loss factor of eta = 0.04 is typical for UHPFRC under tensile cyclic loading, with higher values possible under reversed cyclic and short-duration loading. The unprecedented lightness of the proposed guideway, together with the high strength of GFRP, means that serviceability and fatigue limit states govern the dimensioning of the girders. This calls for a rational means of assessing the vibration response of the guideway system, from the points of view of passenger comfort and girder fatigue life. A frequency-domain method for the analysis of train-girder interaction dynamics is developed and presented. Relative to existing analysis methods, this approach eliminates the need for Monte Carlo simulation of random track irregularities, and allows for rapid assessment of the effects of long-term deformations.