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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Effect of Open-Loop or Closed-Loop Deflection Control on Measured Toughness of FRC
Author(s): R. Gupta and N. Banthia
Publication: Symposium Paper
Appears on pages(s): 67-82
Keywords: closed loop; fiber-reinforced concrete; open loop; toughness
Abstract:Effect of open- or closed-loop deflection control on the measured flexural toughness of fiber reinforced concrete (FRC) was investigated. Third-point loading tests were performed as per ASTM C1609M on several high strength concrete mixtures containing low volume fractions of single, double and triple-fiber blends. A 3-stage loading sequence was adopted for the closed-loop deflection control tests to fully capture the load vs. deflection response immediately after the peak-load.
The results indicate that the open-loop tests produce high instability in the load deflection curves after the peak-load. However, contrary to general belief, the open-loop tests also overestimated the flexural toughness compared to the closed-loop deflection control tests. Manually removing the instability from the open-loop curves helped bring the open-loop toughness values closer to the closed-loop toughness values.
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