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Abstract Fiber-reinforced polymer (FRP) tendons and reinforcing bars (rebars) have been developed for use with concrete. FRP products are non-corrosive and lightweight when compared to traditional steel members. The current test program involves the design,fabrication, and testing to failure of two full-scale high-strength concrete bridge beams with FRP products for prestressing and shear reinforcement. Ó 2000 Elsevier Science Ltd. All rights reserved.23985
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Keywords: Bridge beams; Prestressed; High-strength concrete; Carbon-®ber-reinforced-polymers; Composite; FRP; Tendons; Leadline; C-Bar;Rebar; Bending moment; Ultimate strength tests.1. Introduction
Of the 583 000 bridges in USA, 235 000 are non-pre-
stressed steel-reinforced concrete and 108 000 are steel-
prestressed concrete [1]. A major problem with this steel/
concrete composite construction is corrosion of the steel
members. In recent years, ®ber-reinforced polymer (FRP)
tendons and reinforcing bars (rebars) have been devel-
oped for use with concrete. FRPs oer improved corro-
sion and fatigue resistance compared to steel. These FRP
products oer the possibility of reinforced/prestressed
concrete bridges with greatly increased life in corrosive
environments compared to steel/concrete construction.
In the current program, full-scale FRP-prestressed
and reinforced high-strength concrete bridge beams
were designed, fabricated and tested. The current pro-
gram provided a single-point assessment of the appli-
cability of current design methods to FRP-prestressed
and reinforced concrete bridge beams.
2. Current state of design code development eort
Current design guidelines for steel-reinforced concrete
[2] are the result of decades of research and ®eld experi-
ence. Because of their composite nature, FRP rein-forcements behave not only dierently from steel, but
also with more complicated modes of response. There-
fore FRP reinforcement technology and practices remain
in a developmental state despite numerous research
investigations and some successful ®eld applications.
A brief review of FRP prestressing work is provided.
2.1. Design code development eorts
In 1996, the Federal Highway Administration
(FHWA) of the US Department of Transportation ini-
tiated a four-year research program entitled ``FRP
Prestressing for Highway Bridges''. This program is in-
tended to advance all areas related to product standards
and design codes. Under this program, a survey of code
development eorts in other countries was conducted
[3]. The American Concrete Institute (ACI) Subcom-
mittee 440-I on FRP Prestressing is working to develop
a design code for FRP-prestressed concrete [4]. ACI
Committee 440 on FRP Reinforcement has published a
report summarizing the state of the art of all FRP
reinforcement technology for concrete as of 1996 [5].
A provisional design code for FRP-reinforced concrete
developed in Japan has been translated into English [6].
2.2. Fiber characteristics
While carbon [7±14], glass [8,15,16], and Kevlar [8,9]
have all been investigated as ®bers for FRP prestressing,carbon-®ber-reinforced polymers (CFRPs) have
emerged as the leading FRP material for prestressing.
Experiments have shown CFRP to have 0 creep loss
over a period of 1 year [17] and to have 0 strength loss
due to salt water exposure in experiments ranging from
6 months to 1 year [11,17]. Exposure of CFRP to an
alkaline environment was found in one study to have no
eect on strength after 6 months [11]. In another study,
CFRP was exposed to an alkaline environment for 1
year, and was found to have ``... an equal or greater
resistance than that of regular steel tendon [17]''. A