Long-Term Deflection of Fiber Reinforced Polymer Concrete Beams

Abstract

The effect of FRP material properties on the long-term deflection of concrete beams reinforced with FRP rods was investigated by the experiment of 17 beams reinforced by nine types of FRP rods and a beam reinforced by steel bars. Test results showed that the flexural stiffness of a cracked beam decreased rapidly with a reduction in tensile stiffness of the reinforcing rods. Compared to the short-term deflection of beams, the long-term deflection of the FRP reinforced concrete beams at one week after loading increased on average by 17 percent, and 57 percent at 10 months. The material properties of FRP rods had a great effect on the long-term deflection of beams. The long-term deflection increase of beams with GFRP was the smallest among all of the testes beams, and oppositely, the deflection increase of beams with AFRP was greater than the average. The rate of increase in deflection of the beams reinforced with braided rods was about 10 percent smaller than that of beams with smaller rods. Contrasting, the rate of deflection increase of beams with ribbed rods was about 10 percent greater than that of beams with spiral rods.