Details:

Creators:
Higgins, Christopher ; Williams, Grahme ; Elkins, Lori
Higgins, Christopher ; Williams, Grahme ; Elkins, Lori Less -
Corporate Creators:
Oregon. Department of Transportation
Subject/TRT Terms:
[+]
Bridge Decks Concrete Bridges Concrete Bridges¿Cracking Crack And Seat Treatment Cracking Girder Bridges Girders Pavement Cracking Pavements, Concrete¿Cracking Pavements, Reinforced Concrete¿Cracking Polymer Concrete Reinforced Concrete Bridges Transverse Cracking
Publication/ Report Number:
FHWA-OR-RD-06-16
Resource Type:
Tech Report
Geographical Coverage:
Oregon
Corporate Publisher:
Oregon. Dept. of Transportation
Abstract:
The technique of using carbon fiber reinforced polymer (CFRP) for strengthening conventionally reinforced concrete

(CRC) girders in flexure is well understood, but strengthening girders for shear is a newer application and less data are available.

A literature review and survey were conducted to document the state of understanding and experience with respect to using CFRP

for shear reinforcement of CRC girders. A laboratory investigation using full-size T- and inverted T-girder specimens with

diagonal (shear) cracks was conducted to investigate the shear capacity improvement due to CFRP reinforcement and the effect of

cyclic loading on CFRP shear strengthening. National and international code provisions for the design of CFRP in shear were

used to compare the predicted shear capacity with the experimental results. An example application was included for using

external CFRP strips to strengthen a bridge girder.

Strengthening with carbon CFRP strips provided a significant increase in load capacity and stiffness compared to

unrepaired beams, and the improved capacity was maintained even after being exposed to the equivalent of twenty years of

traffic-induced fatigue. At high load levels prior to failure, progressive debonding of multiple strips provided a clear, visual

warning of distress.

The ACI 440 methodology provided a reasonably simple approach for shear capacity prediction of RC girders with

externally bonded CFRP shear reinforcing for T-beams and is recommended for design. However, the ACI 440 method was

unconservative where the CFRP strips terminate in the flexural tension zone. To provide a consistent level of reliability between

T- and inverted T- conditions, the CFRP stress should be reduced by a factor of 2 for conditions when the CFRP strip is

terminated in the flexural tension zone.

Placement of at least one CFRP strip across the diagonal crack with an anchorage length of at least one-half the height of

the web is critical. An equation for strip layout is presented. In addition, girder shear strength can be increased using a targeted

repair approach, applying CFRP material only to key critical sections rather than over the entire member. Thus, better economy

may be achieved by judiciously applying CFRP materials just to those sections that are understrength for shear.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:84047f06a483003a64fdc48487eb441e148b9c4e6a6ad01f2b57fc5b02d6dbc6
Download URL:
https://rosap.ntl.bts.gov/view/dot/21866/dot_21866_DS1.pdf
File Type:

Supporting Files

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