Effects of radial stress at anchor zone on tensile properties of basalt fiber-reinforced polymer tendons

Abstract

This paper investigates the effects of radial stresses induced by anchoring component at anchor zone on the tensile properties of basalt fiber-reinforced polymer tendons and proposes allowable radial stresses for design and application. The tensile experiments were first conducted to determine the tensile strength of basalt fiber-reinforced polymer tendons with different types of anchorage including bonding, friction, and compression with protective layer to achieve different levels of radial stresses. The longitudinal compressive strength, transverse compressive strength, and in-plane shear strength of basalt fiber-reinforced polymer tendons themselves were also measured for theoretical prediction. On the basis of experiments, the theoretical analysis by Hoffman strength criterion on ultimate tensile strength of basalt fiber-reinforced polymer tendon was conducted according to the above experimental results while the allowable axial stress for application was studied accordingly. The results show that the radial stress affects significantly on the ultimate strength of basalt fiber-reinforced polymer tendon. The mean values of ultimate strength of basalt fiber-reinforced polymer tendons anchored by friction and compression with different radial stresses are 5, 12, and 15% lower than that of the specimens by bonding anchor. Hoffman strength criterion is proven to be an effective model in predicting the ultimate strength with different anchorages. For 6 mm basalt fiber-reinforced polymer tendon, the radial stresses at the anchor zone are recommended to be below 50 MPa to assure no strength reduction and below 90 MPa with allowable 10% strength reduction. Radial stress is not allowed to exceed 130 MPa to avoid compression failure. The prediction method can guide the design of effective anchorage for the prestressing application of basalt fiber-reinforced polymer tendon.