The experience of past earthquakes and the weak seismic performance of some structures have highlighted the need for modern seismic systems. Therefore, further examination of lateral seismic systems, such as energy dissipation dampers, is essential for improving the seismic performance of existing systems. Energy dampers can generally be divided into two categories: velocity-based dampers, such as viscous dampers, and displacement-based dampers, such as yielding and friction dampers. Friction dampers are one of the most effective energy dissipating devices in structures, capable of dissipating seismic energy through friction without causing damage (yielding). This paper studies a new system combining a knee-braced frame (KBF) with a friction damper (KBFD). The damper used is a linear friction damper with a slotted bolted connection. The goal of incorporating the friction damper in this configuration is to help prevent out-of-plane buckling of the brace equipped with the damper and to maximize the capacity of damper to improve the seismic performance of the KBF. In this paper, the finite element model of the KBFD was first validated using experimental results. Then, six types of KBFD frames, with varying pre-tension forces in the friction damper considered as a variable parameter, were studied. These studies included performing pushover analysis to calculate the seismic parameters of the structure, such as ductility and behavior factors. The results of these analyses indicate an improvement in the seismic performance of the KBFD compared to the KBF, with both the ductility and behavior factors increasing. Based on the results, with increasing pre-tension force, the behavior factor also increases and is suggested to range between 7.9 and 9.0. Additionally, these frames were subjected to cyclic loading to further study their seismic behavior. The results of the frame analyses were reported as hysteresis curves, initial and secant stiffness, frame resistance, ductility, behavior factor, dissipated energy, and equivalent viscous damping. The results demonstrate that the friction damper effectively reduces the seismic demand on the braces and columns. Furthermore, the obtained hysteresis curves show a high level of input earthquake energy dissipation and appropriate seismic performance of the frames with the proposed configuration.