United States Department of Transportation
i
A novel methodology for quantifying the performance of constructed bridges in cold regions.
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2014-04-01
[PDF-2.08 MB]
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Abstract:This report presents a two-part research program examining the performance of constructed bridges in a
cold region, represented by those in the State of North Dakota, and the behavior of concrete members
strengthened with carbon fiber reinforced polymer (CFRP) composite sheets in such a service condition.
For the first phase, a total of 1,328 decks are sampled from a 15-year inspection period. These data are
statistically characterized and probabilistically analyzed. The importance of timely technical action is
discussed to enhance the condition rating of the bridge decks. The stochastic response of the existing
decks is effectively represented by Gaussian probability distributions, regardless of inspection years. The
performance of the decks tends to converge to a certain state with time. The state-transition of the in-situ
decks is identified through the global health index proposed. The second part of the research concerns
predictive investigations into the axial behavior of concrete exposed to aggressive service environments.
Two types of concrete cylinders are studied: unconfined and confined with CFRP sheets. The aggressive
environment and service traffic load are represented by freeze-wet-dry cycles with various levels of
instantaneous compression load varying from 0% to 60% of the capacities of the unconfined and confined
control concrete. Research approaches include three-dimensional deterministic finite element and
probabilistic models, associated with a previously conducted experimental program. The effect of the
instantaneous live load is significant on the performance of the unconfined and confined concrete,
including the variation of compliance and volumetric characteristics. The efficacy of CFRP-confinement
increases when the intensity of the live load increases. Reliability performance of the confined concrete is
influenced by the environmental and physical conditioning. Refined design recommendations such as
strength reduction factors are proposed to address the detrimental contribution of the environmental and
physical attributes to the performance of CFRP-confined concrete, based on a Monte Carlo simulation
that can cover over 95% of all possible cases in a normal probability distribution of the confined concrete
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