Shear behavior of epoxy joints in precast segmental bridges under impact loading

Abstract

As an essential component for transmitting shear forces, the epoxy joint of precast concrete segmental box girder bridges (PCSBs) is threatened by impact in their service life. This study experimentally and numerically investigated the impact responses of epoxy joints. Firstly, experimental tests were carried out on the epoxy joints with different confining stresses under static loading and the drop-hammer impact, respectively. Then, the numerical models of epoxy joints under impact loads were developed in LS-DYNA and carefully verified compared with the experimental results. Finally, the calibrated numerical model was applied to predict the dynamic shear capacity of the epoxy joint with different loading rates. The results show that the failure mode of epoxy joints under impact loading is the shear-critical mode. When the impact energy is relatively high, the concrete key will suffer compression damage and even be sheared off directly. The epoxy joints with high confining stresses exhibit little damage and less deformation. In addition, impact events with high mass but low velocity are severe in joint damage when the impact energy is equal. An improved analytical expression was proposed to predict the dynamic shear strength of epoxy joints under different strain rates. The derived formulas can generally predict the dynamic shear strength of epoxy joints of PCSBs.