Study on mechanical behaviors of FRP-to-steel adhesively-bonded joint under tensile loading

Due to various advantages of Fiber–Reinforced Polymer (FRP) decks, the FRP to steel composite girder system is being increasingly used in new bridge constructions as well as rehabilitation projects for old bridges. This paper focuses on the mechanical behavior and failure mode of the adhesively-bonded joins between FRP sandwich decks and steel girders. The adhesively-bonded joints were experimentally investigated under tensile loading. The average ultimate failure load of surface pretreated specimens was 17.62 kN, which was 9.83% higher than that of un-pretreated specimens. Further comparison on failure modes confirmed that the surface pretreatment can improve the bonding quality between FRP composites and adhesive layer, and the failure load of the adhesive joint closely related to the FRP delamination area. Furthermore, a 3D numerical modeling was conducted using ABAQUS 6.8. The Finite Element Analysis (FEA) results were validated with experimental works focused on the deformational response of the adhesively bonded joints. The results of FEA highlight the three-dimensional nature of the stress distribution and stress concentrations at the interface between FRP sandwich deck and adhesive layer.