Posttensioning of segmental bridges using carbon-fiber-composite cables

摘要

Carbon-fiber-composite cables (CFCC) offer a corrosion-free alternative to steel strands. This paper describes the construction and testing of a 31/2:1 scale model of the Long Key segmental box girder bridge model posttensioned with CFCC or steel strands at different prestress and for different loading configurations. The study shows the feasibility of CFCC for segmental bridges. The main concern, however, is that end anchorages are factory-made together with the strands, and therefore, strands must be ordered at predetermined lengths, considering the elongation of stressed tendons. The model behaved bilinearly with both types of strands. Whereas initial stiffness was about the same for both types of strands, CFCC tendons led to a much softer response after decompression and joint opening. Given the higher flexibility of the segmental bridge model posttensioned with CFCC, a stiffness-based equivalency approach may provide a more comparable performance with the same bridge model posttensioned with steel. Such an approach, however, may lower the stress in CFCC commensurate with its lower elastic modulus.