Tensile Property Of FRP Tendons And Bond Behavior Between FRP Tendons And Concrete

Several types of glass fiber reinforced polymer(GFRP) tendons and steel-glass fiber reinforced polymer(S/GFRP) tendons were produced in laboratory for relative tests. The effects of diameter and steel volume ratio on the tensile strength and elasticity modulus of FRP tendons were studied by means of experiment. The bonding properties of FRP tendons in concrete were experimentally studied through direct pullout tests and the diameter, rib depth, ribs distance and steel volume ratio were selected as test parameters.The main contents are as follows:1. To test the tensile strength and elasticity modulus of GFRP or S/GFRP tendons, the specimens were divided into 7 groups(each group of 5 specimens) by diameter and steel volume ratio. The results indicated that the elasticity modulus of S/GFRP tendons are significant improved than the GFRP tendons and it increases with the increase of steel volume ratio. And the tensile strength of FRP tendons are increased with the decrease of diameter. But, when the diameters are equal, the tensile strength of all the GFRP or S/GFRP tendons are close. To illustrate effects of the steel on the S/GFRP tendons, the cooperation coefficient β is introduced and the suggested value is 0.45.2. The bonding properties between GFRP or S/GFRP tendons and concrete was discussed in this paper based on the pullout test results of 8 groups(each group of 3 specimens) specimens. In the tests, the diameter, rib depth, ribs distance and steel volume ratio was the parameters. And the concrete split failure happened in all the specimens. The results indicated that the bond strength between GFRP tendons and concrete, which was little affected by ribs distance, are increased with the decrease of diameter and the increase of rib depth. The existence of the steel in the S/GFRP tendons could improve the bond strength between GFRP tendons and concrete. But the steel volume ratio have little influence on it.3. The calculation methods of the bond strength and anchorage between GFRP or S/GFRP tendons and concrete was presented according the test results. The existing bond-slip constitutive relation models between FRP tendons and concrete were summarized. The ascending branch of bond-slip constitutive relation curve of FRP tendons and concrete was simulated with BPE model, and model curves are in good agreement with experimental curves.