INNOVATIVE HYBRID FRP-CONCRETE TRUSS BRIDGE GIRDERS

摘要

An innovative corrosion-free system for short- and medium-span bridges in currently underdevelopment at the University of Calgary. The new system consists of precast prestressed concrete trussgirders and cast-in-situ concrete deck. The truss girders consist of top and bottom concrete flangesconnected by precast vertical and diagonal members made of fibre reinforced polymer (FRP) tubes filledwith concrete. Glass FRP dowels protrude from the ends of the verticals to connect them to the concreteflanges. Corrosion-resistant stud reinforcement connect the diagonals to the flanges. The FRP tubesserve as stay-in-place formwork, confine the concrete core, provide tensile reinforcement, and protect theconcrete from the environment. The concrete flanges of the truss are pretentioned with carbon FRPtendons. The reinforcement in the deck slab is glass FRP in three directions and corrosion-resistant steelin one direction. The truss girders can be post-tensioned with external carbon FRP tendons to balance theweight of the slab and to provide continuity between the different spans in continuous bridges. Theinnovative system has the advantages of reduced self-weight and enhanced durability. The light weightreduces the initial cost and allows for longer spans; the improved durability reduces the maintenance costand can extend the life span to 100 years, instead of the 50 years for which many of the existing bridgeswere designed but failed to achieve. This paper presents an experimental evaluation of the most importantaspects of the proposed system, including the effects of different types of FRP tubes on confining theconcrete in the truss members, and the performance of different types of connections between the trussmembers and the concrete flanges. The research has thus far provided positive results.