During the Northridge and Kobe earthquakes, many of steel moment-resisting frames at the beam-to-column connection were damaged due to excessive deformation. As a solution, steel slit dampers were used in the connections to prevent the connections’ fracture and damage of the main members of the structure. In the present paper, a numerical investigation was carried out with ABAQUS software to investigate the parameters affecting the seismic performance of steel slit damper in beam-to-steel column connections. The damper specimen were simulated and verified with an experimental work under cyclic and monotonic loading. A reasonable agreement was obtained between the finite element analysis and the experimental test results. For easy expression of the damper performance criteria, monotonic loading were used by presenting the results in the form of moment-rotation. The variables studied included the various proposed shapes for the damper, damper boosting effect, and damper thickness in the seismic performance of beam-to-steel column connection. The results show that with increasing the thickness and strengthening of the steel slit damper, the bending moment, stiffness and energy dissipation capacity of the connection, increases. Also, the new proposed slit damper had the best performance among the other dampers.
