Introduction - Reinforced Concrete with FRP Bars: Mechanics and Design - page 4

the direction of the fibers [14-17], with no yielding. A flexural concrete
member reinforced with FRP rebars generally experiences extensive
cracking and large deflections prior to failure, which is, typically, sudden
and catastrophic. The shear strength and dowel action of FRP rebars as
well as the bond performance are affected by the anisotropic behavior of
the bars [3]. Furthermore, the behavior of FRP bars in compression is not
as good as the one in tension. Due to the FRP anisotropic and nonho-
mogeneous nature, the compressive modulus is lower than the tensile one
[15,18]. There is still little experience in the use of FRP reinforcement in
compression members (columns) and for moment frames or zones where
moment redistribution is required [19].
Several global activities have taken place to implement FRP rebars into
design codes and guidelines since the 1980s. In the United States, the ini-
tiatives and vision of the National Science Foundation and the Federal
Highway Administration promoted the development of this technology
supporting research at different universities and research institutions [9].
In 1991, the ACI established Committee 440, ''FRP Reinforcement.” The
objective of the committee was to provide the construction industry with
science-based design guidelines, construction specifications, and inspection
and quality control recommendations related to the use of FRP rebars for
concrete structures. In 2001, Committee 440 published the first version
of the document “Guide for the Design and Construction of Structural
Concrete Reinforced with FRP Bars” [20]. The availability of this docu-
ment further expedited the adoption of FRP rebars.
While the use of FRP reinforcement in buildings in the United States is
within the jurisdiction of ACI, new bridges financed with federal funds have
to be designed following the American Association of State Highway and
Transportation Officials (AASHTO) load and resistance factor design (LRFD)
bridge design specification. The lack of AASHTO limit-state-based specifica-
tions covering the design of FRP reinforced concrete bridge deck systems was
the last barrier to sanction the acceptance of this innovative and already com-
petitive technology. In 2007, a task force led by researchers, consultants, and
representatives from State Departments of Transportation and the US Federal
Highway Administration developed LRFD design specifications written in
mandatory language. While maintaining the AASHTO provisions for the def-
inition of loads, load factors, and limit states, the document covered specific
material properties and detailing of FRP reinforcement, and defined applica-
ble design algorithms and resistance factors. The proposed guide, “AASHTO
LRFD Bridge Design Guide Specifications for GFRP-Reinforced Concrete
Bridge Decks and Traffic Railings,” was approved by the Subcommittee on
Bridges and Structures in May 2008 and published in December 2009 [21].
In addition to FIB (Fédération Internationale du Béton) bulletin 40,
“FRP Reinforcement in RC Structures,” published by the International
Federation for Structural Concrete [22], some historical and well-known