Title: Bond Behaviour of CFRP Bars Prestressed in Self-Consolidating Concrete Beams
Author(s): Slamah S. Krem and Khaled A. Soudki
Publication: Symposium Paper
Appears on pages(s): 36.1-36.20
Keywords: CFRP, prestressed beams, self-consolidating concrete, transfer and development lengths
Self-consolidating concrete (SCC) is an emerging technology that provides improved productivity and quality of concrete construction. The current ACI 440.4R-04 design guideline does not account for SCC in the calculation of the transfer and development lengths of prestressed CFRP bars. Recent developments in the FRP bar manufacturing process can significantly affect the bond behavior of FRP bars in concrete. This paper presents measurements from 16 beams prestressed with 12.7 mm (½̏) CFRP bars. Transfer length was determined through longitudinal concrete strain profile and draw-in measurements, and development length was determined by flexural tests. The results revealed a nonlinear variation in the transfer length of CFRP bars in SCC versus the prestressing level. Prediction of the transfer and development length predictions for the 12.7 mm (½̏) CFRP bar based on ACI 440.4R-04 are unconservative when the prestressing level exceeds 750 MPa (110 ksi). The paper proposes a modification to the existing ACI 440.4R-04 equation to account for SCC. At a 90 % confidence interval, the test results show an average deviation of ± 8 % for the proposed model.