The base-isolation system makes the base more flexible than the elements of the superstructure part which make the sliding displacement through the base increases which tend to increase the total displacement. The effect of increasing the total displacement will make a harmful effect if the buildings not have a sufficient separation distance between them. So this paper investigates, through numerical simulation, the effect of the presence of the viscous dampers at the points of the collision in Base-Isolated structures on the reduction of the pounding force. A specialized program has been made in order to efficiently perform numerical simulation and parametric studies on the control system. The effects of certain parameters have been investigated using the developed software such as damper yield force, damper stiffness and post-pre stiffness ratio to find the optimum parameters of the viscous damper which minimizes the energy transmitted to the overall system. The results demonstrated that, the presence of viscous dampers at the floor levels at the points of contact increases the dispersal of energy generated by the collision. Also, after a specific value of connected dampers stiffness, the increase of the stiffness reduces system response.