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原文传递 Evaluation of the FRP-Retrofitted Arches in the Castlewood Canyon Bridge. Final rept.

题名：	Evaluation of the FRP-Retrofitted Arches in the Castlewood Canyon Bridge. Final rept.
作者：	CHANG, S.; FAFACH, D.; SHING, B.; XI, Y.
关键词：	Retrofitting-; Carbon-fiber-reinforced-plastics; *Arch-bridges.;Durability-; Colorado-; Bridge-maintenance; Concrete-; Shotcrete-; Peeling-; Bond-strength.
摘要：	Fiber-reinforced composites are increasingly being used for repair of deteriorating and understrength concrete decks and columns due to their excellent properties. Carbon fiber-reinforced polymers (CFRP) sheets were used in this project to strengthen the arch. Four quarter-scale beams were tested to model the arch ribs before and after the retrofit to evaluate the strength of the arches. Two of the beams were designed to model the behavior of an arch rib below a heavily loaded column. The remaining two beams were designed to model the moment connection at the base of an arch. The test results were used to calibrate an analysis technique which was used to predict the strength of the full-scale arches. The retrofitted test specimens were between 22%and 30%stronger in bending than the control specimens. However, the strengthening scheme did not increase the strength of the retrofitted specimens as much as expected. The externally bonded FRP ruptured earlier than expected in one test specimen. Another specimen experienced peeling of the concrete which led to bond failure of the FRP rods. Durability of bond between CFRP and concrete was studied by the pull-off bond strength test after various long-term conditioning, including room temperature, wetting in water, wetting/drying in water, immersion in 3%NaCl, freeze-thaw, immersion in 0.2N NaOH, and high temperature. The experimental results indicate that the bond strengths satisfy the selected acceptance criterion, although the bond strengths were significantly affected by the long-term environmental exposures. However, the bond failure modes were unsatisfactory based on the ACI criterion in that the ideal failure mode is to have 100%failure in substrate. A wireless real-time remote bridge monitoring system was installed on the bridge site to evaluate the performance of the arch and the effectiveness of the corrosion inhibitor applied in the arch rib. The maximum strain recorded was 1400 ma (0.14%) under the service conditions, which is about 23%of the minimum ultimate rupture strain. The chloride content and the corrosion potential in the new shotcrete cover have been increased, which are due to the re-distribution of the existing chloride in the old concrete.
报告类型：	科技报告