This research paper presents a pioneering investigation into the dynamic behavior of retaining structure by integrating a viscoelastic soil model for backfill material overlying the rigid bedrock, with a specific focus on examining the effect due to the variations in friction angle and damping ratio for different horizontal acceleration amplitude. A closed-form expression for seismic active earth pressure is derived using a modified pseudo-dynamic approach, assuming a planar failure surface. The study addresses the inadequacies of conventional methods in accurately predicting active earth pressures under seismic loading conditions. By critically reviewing existing methodologies and analytical investigations, the proposed approach showcases parametric sensitive study for variables like friction angle and damping ratio, such as those near fundamental frequencies of the backfill material. By accounting for the time-dependent behavior and damping effects inherent in the soil, the modified approach is a rational framework for dynamic analysis. The study results emphasize the significant influence of the damping ratio on seismic active earth pressure. At the same time, the increment of active earth pressure is observed with a decrease in the damping ratio of the soil.