Failure Criteria for Debonding of Patch Plate Bonded Onto Steel Members Subjected to Bending

Abstract

Recently, externally bonded patch plates have been widely used for the repair or strengthening of steel members due to their ease of application. When the traffic loads are applied on the steel members strengthened with patch plates, shear and normal stresses are introduced to the adhesive layer especially in the vicinity of the patch plate end. Due to the higher shear and normal stresses at the end of the patch plate, the debonding of the patch plate from the steel member could occur before the yielding of steel member or patch plate. To prevent debonding of the patch plate, the shear and normal stresses in adhesive have been studied using theoretical, numerical, and Finite Element analyses. Meanwhile, the failure criterion for debonding has not been clarified. In this study, to develop the verification method for debonding, some failure criteria were compared. The compatibility of each failure criterion was validated from the debonding test.