Time‐Dependent Anisotropy Coefficient and Prediction Model of Ductile Composite Rebar After Exposure to Artificial Concrete Environment

ABSTRACT Hybrid fiber composite (HFC) rebar with tensile ductility is an outstanding alternative to steel bar in structural concrete due to its superior overall performance. However, the constituent configuration of HFC rebar makes it belong to an anisotropic material. In this study, the correlation between lateral shear strength and tensile strength of HFC rebar was used to simplistically characterize its anisotropy coefficient. Nevertheless, the durability deterioration of HFC rebar makes the anisotropy coefficient become a time‐dependent variable after exposure to concrete environment. Therefore, this study considered the carbon/glass‐HFC (C/G‐HFC) rebar after exposure to artificial concrete solution for different periods as the research object. The effects of carbon/glass ratio, fiber package configuration, fiber whole volume fraction, and exposure period on the anisotropy coefficient of C/G‐HFC tendon were explored. Meanwhile, scanning electron microscope, X‐ray diffraction, Fourier transform infrared spectrometer, and water absorption tests of C/G‐HFC rebars were employed to reveal the time‐dependent mechanism of anisotropy coefficient. Finally, considering the characteristic parameters of C/G‐HFC rebar and exposure period, the prediction models of anisotropy coefficient were proposed for C/G‐HFC rebar under normal environment and after exposure to concrete environment. The consistency between predicted values and experimental results proved the effectiveness of proposed models.