Damage evaluation of a welded beam-column joint with surface imperfections subjected to impact loads

The weld imperfections often exist, which affect the loading capacity of the joint. The study of welded joints with surface imperfections subjected to impact loads is limited in open literature. In this study, the influence of weld surface imperfections on the performance of steel beam-column joint under impact loads is numerically investigated by using software ABAQUS. The common surface imperfections (i.e. sagging, incompletely filled groove and undercut) are considered. The damage mode, impact force and mid-span displacement of the beam-column joint with surface imperfections are obtained and compared with those of the joint without imperfection. Structural responses of the joint corresponding to various impact scenarios (i.e. different combinations of impact mass and velocity) are compared and analysed. A best-fit equation is presented to predict the maximum displacement of the joints under impact. The effects of imperfection forms and locations on the post-impact performance of the joint are also investigated, and its residual bearing capacity is compared. In addition, damage index based on the residual bearing capacity of the joint is proposed to evaluate the damage level of the joint subjected to impact. Four damage levels are defined based on the post-impact performance of the joint. The impact mass-velocity diagrams are generated to predict the damage level of the joints subjected to possible combinations of impact mass and velocity.