FRP/UHPFRC Composite Structural Systems for Elevated Rail Transit Structures

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The long-term goal of the proposed research is to develop a new type of lightweight girder suitable for elevated structures carrying light rail transit. The proposed single-cell box girder uses fibre reinforced polymer (FRP) and ultra high-performance fibre reinforced concrete (UHPFRC) acting compositely. Composite action enables each material to mitigate shortcomings in the other while maintaining its own intrinsic advantages, making possible a prefabricated system that is economical, easy and fast to construct using conventional means, durable, and which offers aesthetic possibilities superior to structural systems currently used.**The short-term goals seek to fill the following gaps in knowledge necessary to validate the proposed system: **1. Develop and validate a reliable means of transferring shear force along the interface between FRP and UHPFRC to ensure that both materials can work together at all levels of load**2. Characterize the fatigue resistance of the UHPFRC/FRP composite. Rail transit structures are subject to significant cycles of stress due to the passage of trains. It is necessary to ensure that the composite material will not undergo significant progressive damage due to these cyclic stresses.**3. Characterize the intrinsic damping of the UHPFRC/FRP composite. Rail transit structures must be designed to minimize vibrations, for the comfort of passengers and to ensure proper operation of vehicles. To provide an adequate basis for design, a proper quantification of the intrinsic damping of the material is required.**4. Develop critical structural details for structural continuity and validate the design concept over a representative range of spans and curvatures.**Due to its light weight, efficient consumption of materials, and ease of construction relative to other recently used structural systems, the proposed girder offers many possibilities for cost savings. The most important of these include a significant reduction in labour for both fabrication and erection, reduction in the size and reinforcement of piers and foundations due both to reductions in dead load reaction as well as reduced seismic vulnerability due to its extreme light weight. The proposed research thus has the potential to bring about a significant reduction in the capital costs of light rail systems and thus to encourage the creation and expansion of rapid transit networks in Canadian cities.