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1. INTRODUCTION
Of all elements in a bridge superstructure, bridge decks may perhaps require the
maximum maintenance, for reasons ranging from the deterioration of the wearing surface to the
degradation of the deck system itself. Added to the problems of deterioration are the issues
related to the need for higher load ratings (HS20 to HS25, for example) and increased number of
lanes to accommodate the ever-increasing traffic flow on major arteries (Lopez-Anido and
Karbhari 1990). Beyond the costs and visible consequences associated with continuous retrofit
and repair of such structural components are the real consequences related to losses in
productivity and overall economies related to time and resources caused by delays and detours
(See for example, Ehelen and Marshall, 1996). Reasons such as those listed above provide
significant impetus for the development of new bridge decks out of materials that are durable,
light and easy to install. Besides the potentially lower overall life-cycle costs (due to decreased
maintenance requirements), decks fabricated from fiber reinforced composites are significantly
lighter, thereby affecting savings in substructure costs, enabling the use of higher live load levels
in the case of replacement decks, and bringing forth the potential of longer unsupported spans
and enhanced seismic resistance. However, the response of FRP composite decks to fatigue
loading in extreme temperatures has not been studied extensively (Lopez-Anido et al. 1998,
1999; Kwon et al. 2001).
An evaluation plan for FRP bridge decks has been recently proposed by the HITEC
program (Karbhari 2000). The panel has identified key technical issues and proposed
performance verification tests related to: a) Structural system response, inspection, maintenance
and repair; b) Joints and connections; and c) Materials and manufacturing. The Federal Highway
Administration and the Ohio Department of Transportation is conducting an evaluation program
for four different FRP bridge deck systems, which ranges from durability characterization and
structural fatigue testing to field installation and monitoring (Triandafilou 2000). Preliminary
fatigue test results were reported (Lopez-Anido et al. 2001).
In this study, experimental fatigue evaluation of five deck prototypes, which included
three full-size FRP composite bridge decks, one hybrid FRP-concrete deck, and one reinforced-
concrete conventional bridge deck, was conducted (See Figure 1 and Table 1). The deck
prototypes were evaluated under two extreme temperatures to assess the fatiguetemperature
response. Each deck prototype was initially subjected to one million simulated wheel load cycles
at low temperature, 30C (22F), and another one million cycles at a controlled high
temperature, 50C (122F). The results of these initial tests were presented by Lopez-Anido et al.
(2001). The results presented in this paper correspond to testing each deck prototype for an
additional four million cycles at low temperature and four million cycles at high temperature.
Besides, three different polymer concrete wearing surfaces, each 3.7 x 0.45 m (144 x18 in) and
13 to 19 mm (0.5 to 0.75 in), from three different vendors were provided on each of the three
FRP composite bridge decks.
Quasi-static load tests were conducted at specific intervals during fatigue cycling to
evaluate the load-deflection and load-strain responses at several deck locations. The
experimental results were correlated with the performance of a conventional reinforced-concrete
deck subjected to the same series of tests.
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