Fibre reinforced polymers (FRP’s) are considered an alternative to steel reinforcement in concrete structures because of their noncorrosive nature and nonmagnetic properties. FRP materials are, however, brittle and have a lower stiffness compared to steel. The latter property can lead to deflection and crack control problems in FRP-reinforced concrete flexural members under service loads. A considerable amount of information is available for short-term deflection of FRP-reinforced concrete members, but data on long-term deflections are scarce.
This study presents the results of monotonic (short-term) and sustained (long-term)
loading tests of 12 concrete shallow beams reinforced with either steel or glass FRP
(GFRP) bars. The short-term load-deflection responses of the members are evaluated
using existing deflection prediction models (Branson’s and Bischoff’s), and the long-term deflection results (monitored over a period of one year) are used to evaluate the existing ACI code and CSA standard approaches for estimating long-term deflection. The GFRP-reinforced concrete beams exhibited greater amounts of both immediate deflection (under sustained load) and long-term deflections over time, than the steel-reinforced concrete beams. The long-term deflections of both the steel- and GFRP-reinforced concrete beams are overestimated when using the ACI and CSA approaches. Although ACI Committee 440 recommends use of lower values of the long-term deflection multiplier for GFRP-reinforced concrete beams, results obtained from this study suggest that the same longterm multiplier values may be used for GFRP- and steel-reinforced concrete beams loaded at between 115 to 157 days of concrete age.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:UNB.1882/35382 |
| Date | 14 September 2011 |
| Creators | Darabi, Mohammadali |
| Contributors | University of New Brunswick, Faculty of Engineering, Bischoff, P. H. |
| Publisher | Fredericton: University of New Brunswick |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
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