Abstract
state rather than ultimate state. This necessitates verifying the crack width in FRP-reinforced concrete (FRP-RC) members
at service load. Recent developments in the FRP industry led to the introduction of FRP bars with different surface configurations and mechanical properties, which are expected to affect their bond performance. In the absence of test data, the design codes and guides, however, recommend bond-dependent coefficient (kb) values considering the surface configurations. Thus, this study aims at investigating the kb values and verifying the dependency of the kb values on FRP bar type (glass [GFRP] and carbon [CFRP]), diameter, and concrete type, and strength limited to the first critical flexural-crack width. The investigation included 20 beams measuring 4,250 mm long × 200 mm wide × 400 mm deep. The beams were reinforced with sand-coated GFRP bars, helically-grooved GFRP bars, and sand-coated CFRP bars and were fabricated with normal- and high-strength concretes (NSC and HSC). The measured first critical-crack widths and measured strains were used to assess the current kb values recommended in FRP design codes and guides. The findings did not support using the same kb value for FRP bars of different types (carbon and glass) with similar surface configurations. Moreover, the average kb of CFRP bars was smaller than that of GFRP bars of the same bar diameter in NSC and HSC.
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References
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