AbstractNowadays, steel shear walls are widely used as a seismic lateral resistant system all over the world. In this paper, a parametric study is presented to calculate the ratio of length to height (L/H) using numerical methods. Results show that L/H=1.0 has better performance than other ratios with respect to the absorbed energy, initial stiffness, and maximum considered load capacity. Therefore, it can be understood that the most significant effect of retrofitting with a steel shear wall (SSW) based on the maximum load capacity can be found in the model with L/H=1.0. Also, models with L/H ratios of 1.33 and 1.50 have approximately the same increased load ratio. Finally, it can be concluded that changing the L/H ratio does not affect the maximum load capacity and initial stiffness of a concrete frame without SSW. However, the L/H ratio has an essential effect on the behavior of a concrete frame with SSW. The results show that the maximum load capacity is related to L/H=1.5 for the concrete frame with SSW. Finally, the nonlinear viscous damper was used to improve the performance of an SSW. Results show that the value of absorbed energy by two diagonal viscous dampers is higher than that of the chevron viscous damper. Therefore, two diagonal viscous dampers can damp more values of input energy during an earthquake and reduce the response of the structure.