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    CFRP-prestressed scale-model bridge design was fatigue
    tested to 7 million cycles at 60% ultimate load, with
    negligible e€ects on the stress levels and dynamic char-
    acteristics of the bridge [12].
    2.3. Tendon strength characterization
    Manufacturer-supplied strength data for two leading
    CFRP prestressing products were included in Ref. [18].
    Using these data, ratios of guaranteed-strength to ulti-
    mate-strength were computed to be 0.67 for Leadline
    (by Mitsubishi Kasei, Japan) and 0.81 for CFCC (by
    Tokyo Rope, Japan). This discrepancy suggests that
    there is not a consistent methodology in use by di€erent
    tendon manufacturers to establish characteristic
    strength values.
    2.4. Gripping and hold-down issues
    Because FRP tendon materials lack the ductility of
    prestressing steel, it has found been necessary to develop
    new grip/anchor designs for FRP tendon tensioning.
    FRP tendon anchorage technology was reviewed in 1993
    [19]. Reusable wedge-type grips have been developed for
    some speci®c FRP prestressing products [14,19]. Potted-
    end anchorage has been demonstrated using a variety of
    organic resins and cementitious materials as grout
    [16,19,20]. Pretensioned CFRP tendons have been used
    in draped con®gurations, although in one project, con-
    ventional small-radius steel rollers were found to cause
    splitting of the tendons [21]. The steel rollers were re-
    placed with large-radius polymer guide channels as a ®x.
    The issue of safety in the face of grip failures has been
    raised as new gripping technology is being applied in the
    ®eld [9].
    2.5. Transfer length
    Careful tests of transfer length have been performed
    for selected FRP prestressing products [7,13]. No un-
    usual behavior was discovered compared to steel ten-
    dons, though the characteristic transfer lengths di€er
    from steel. Because there is variability in FRP tendon
    composition and surface deformations, the transferlength must be determined for the speci®c product under
    consideration.
    2.6. Thermal expansion mismatch
    The coecient of thermal expansion (CTE) values for
    concrete and steel are similar, approximately 10 ´ 10ÿ6
    /°C
    for concrete and 11 ´ 10ÿ6
    /°C for steel. For an epoxy-
    matrix CFRP tendon, typical longitudinal and transverse
    CTE values are in the neighborhood 70 ´ 10ÿ6
    /°C and
    30 ´ 10ÿ6
    /°C, respectively. Temperature will a€ect bend-
    ing stress levels, and concerns about concrete cracking
    due to transverse expansion of the reinforcement have
    been raised. A concern over beam end splitting was ad-
    dressed in one ®eld application by the addition of helical
    FRP reinforcements in the end regions [21]. The e€ects of
    thermal expansion mismatch have been studied both
    analytically [22] and experimentally [22,23] for the case of
    unprestressed FRP rebar.
    2.7. Ductility concerns
    FRP tendons lack the ductility under extreme loading
    exhibited by steel. Thus, a CFRP-prestressed beam may
    simultaneously provide greater ultimate load capacity
    and lower energy absorption than a similar steel-pre-
    stressed design. Tendons have been distributed over a
    large range of eccentricity values to achieve progressive
    failure [14]. Recent work has advanced the ability to
    predict the de¯ections of CFRP-prestressed beams
    during progressive tension cracking, including load
    cycling [24].
    3. Prestressed bridge beam test program
    Two 12.19 m long AASHTO Type 2 beams were
    designed, fabricated, and tested to destruction in four-
    point bending. The two beams shared the same geo-
    metric con®guration for prestressing tendons and shear
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