Cold region durability of a two-part epoxy adhesive in double-lap shear joints: Experiment and model development

This paper presents the behavior of a two-part epoxy adhesive bonded to a steel substrate (typical combination for FRP-repair of deteriorated steel girder bridges) subjected to cold region environment. A total of 43 specimens are tested using double-lap shear joints in wet–dry and freeze–thaw conditions to examine the durability performance of the joint, including load-carrying capacity, interface deterioration, and failure mode. A three-dimensional modeling approach is proposed to predict experimental findings. The model takes into account debonding characteristics of the interface. Empirical bond-deterioration models are suggested. Load-carrying capacity of the specimens tends to be improved with the environmental cycles possibly due to additional curing of the adhesive in a moisture environment, whereas interface deterioration is accelerated with the cycles. Failure mode of the test specimens is altered from cohesion failure to adhesion failure because of the environmental effects.