Bend capacity of continuous fiber GFRP stirrups with rectangular section

The bend strength is a key control parameter for fiber-reinforced polymer (FRP) stirrup. To investigate the bend capacity of the new type of continuous fiber GFRP stirrups with a rectangular section, the bend strength of nine types of continuous fiber GFRP stirrups with different cross-section sizes and the traditional pultruded stirrups were tested using the ACIB.5 test method. The influences of the form of the stirrup, the width, the thickness, and the width-to-thickness ratio on the bend capacity of the continuous fiber GFRP stirrups with a rectangular section were investigated. The test results show that the bend strength of the new type of GFRP stirrup is significantly improved compared with that of the pultruded stirrup. The ratio of the bend strength to the tensile strength increases with the decrease of the thickness of the continuous fiber GFRP stirrup and decreases with the increase of the width. When the cross-sectional area is certain, the width-to-thickness ratio increases and the ratio of the bend strength to the tensile strength shows a tendency to increase, but the growth gradually decreases. Based on the experimental data, a bend strength prediction model for the GFRP stirrups with a rectangular section considering the effect of bend radius and width-to-thickness ratio was established. The bend radius of the continuous fiber GFRP stirrup is recommended to be taken in the range of 25-40mm. According to the different bend radii, the optimal width-to-thickness ratio of continuous fiber GFRP stirrup is recommended to be taken in the range of 2-8, which could be used in practical engineering.