Transfer Length of Carbon Fiber Rods in Precast Pretensioned Concrete Beams

摘要

This paper presents the results of an experimental study to determine the transfer length of carbon fiber reinforced polymer (CFRP) rods in prestressed concrete beams. Five large-scale concrete T-beams were pretensioned with four 5/ 76 in. (8 mm) diameter CFRP LeadlinerM rods. In addition, four rectangular beams were pretensioned using a single Leadline™ rod. Three levels of prestressing, 50, 60  and 70 percent of the guaranteed strength of the rod, were considered. The strain profile along the length of the beam was determined by measuring the strain in both the prestressing rods and the  concrete. The results of the experiment were used to determine the instantaneous and long-term transfer length of CFRP rods and to examine the applicability of existing equations available for steel. The measured  transfer length for these CFRP rods was 80 to 90 times the bar diameter, and existing models for steel may give unconservative transfer lengths for the CFRP rod.