Creep behavior of epoxy-bonded anchor system

The mechanism of epoxy-bonded anchor system (EBAS) has been studied by many researchers in the past several decades with different models. However its long-term performance is seldom mentioned and characterized in the literature, which has led to the fatal accident in the Ted Williams Tunnel, Boston in July 2006. This paper suggests a theoretical model to characterize the long-term performance of EBAS considering the viscoelastic effect of the adhesive layer. First, the theoretical model is compared with a numerical analysis in ABAQUS and the close matched results were achieved. Furthermore, based on the proposed theoretical model, the time dependent behavior of tensile and shear stresses along the anchor and epoxy interface are derived. The closed-form long-term displacement is obtained as well. Moreover, the initial cracking load is recovered and related to the loading time. It was found that EBAS is not going to crack if it is not cracked at the initial loading time. Finally, a parametric study is conducted to analyze the distinct effect of composition factors of EBAS on its long-term behavior.