Serviceability of concrete beams prestressed by carbon-fiber-reinforced-plastic bars

The use of carbon-fiber-reinforced-plastic (CFRP) as prestressing reinforcement for concrete structures, has increased rapidly in the last ten years. The non-corroding characteristics of CFRP reinforcement could significantly increase the service life of concrete structures. In addition, CFRP prestressing reinforcement has the advantages of high strength-to-weight ratio, good fatigue properties, and low relaxation. However; the linear elastic behavior of the material up to failure requires special design consideration to ensure sufficient deformability of the members. In this paper, partial prestressing using low-jacking stresses, is proposed for the design of concrete members prestressed by CFRP reinforcement to reduce the cost and improve their deformability. The paper summarizes a study undertaken to examine the flexural behavior of concrete beams partially prestressed by CFRP reinforcement. The experimental program consists of testing eight concrete beams prestressed by CFRP bars and two beams prestressed by conventional steel strands. The parameters considered in this experimental program are the prestressing ratio, degree of prestressing, and distribution of the CFRP bars iii the tension zone. The various limit stares behavior of concrete beams prestressed by CFRP bars in terms of cracking and deflection prior and after cracking are examined. The different modes of failure and the deformability of such beams are discussed.