Experimental Study on the Performance of Approach Slabs under Deteriorating Soil Washout Conditions
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VIEW THE REPLYPublication: Journal of Bridge Engineering
Volume 16, Issue 5
Abstract
In the U.S. bridge design practice, an approach slab is commonly provided to facilitate a smooth transition from the highway pavement to the bridge deck. Maintenance of bridge approaches often necessitates the repair or replacement of approach slabs owing to damage from heavy traffic loads, washout of fill materials, and settlement of the approach embankment. Approach slab damage because of embankment settlement is considered a more common problem and has been extensively investigated in the literature. In this paper, performance of the approach slab degraded by void formation underneath the slab is examined by load testing. Full-size approach-slab specimens were tested under increasing magnitude up to four times AASHTO HS20-44 design truck loads. The test matrix included four slab specimens with the following details: (1) conventional steel reinforcement representative of current California design; (2) steel reinforcement replaced by a double-layer pultruded fiber-reinforced polymer grating; (3) steel reinforcement replaced by glass fiber-reinforced polymer rebars; and (4) incorporation of steel and polyvinyl alcohol fibers in the concrete mix and removal of top longitudinal and transverse steel. Results indicated that the slabs show satisfactory performance under standard HS20-44 design truck load. Tests also revealed that these slabs exhibited similar performance in terms of stiffness, deformation, and crack pattern when fully supported, but registered noticeable difference in performance under deteriorating soil washout conditions. The fiber-reinforced concrete slab in general showed the best crack control and the smallest deflection and end rotation among the four slabs.
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Acknowledgments
The research reported in this paper was funded by the California Department of Transportation under Agreement No. CADOT59A0485. Their financial support is gratefully acknowledged. Appreciations are extended to Strongwell Corporation for supplying the double-layer fiber-reinforced polymer grating (Gridform) system and Hughes Brothers Inc., for supplying the glass fiber-reinforced polymer bars. Opinions expressed in the paper are solely that of the authors and do not necessarily represent the view of the sponsors.
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© 2011 American Society of Civil Engineers.
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Received: Apr 20, 2010
Accepted: Sep 27, 2010
Published online: Oct 5, 2010
Published in print: Sep 1, 2011
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