Horizontally curved bridges are widely used due to their geometric compatibility, offering aesthetic and economic advantages. However, the geometric irregularities of such bridges result in more complex and potentially destructive behavior compared to straight bridges. Consequently, numerous studies have been conducted to understand the seismic response of horizontally curved bridges and to implement necessary design considerations. In this study, a parametric analysis was conducted to determine the actual seismic behavior of bridges with varying geometric configurations. 11 earthquake records were selected, scaled, and matched to the defined horizontal elastic response spectrum. A total of 22 ground motion records were applied in the X and Y directions in the numerical models. The seismic behavior of 65 reinforced concrete bridges including 5 straight bridges and 60 horizontally curved bridges was investigated using nonlinear time-history analysis. Parametric numerical models were developed with variables such as bridge length, number of spans, span length, and subtended angle of curvature. Internal force demands in bridge structural elements, base shear forces, and pier top displacements were obtained over time under the combined effects of seismic loads and self-weight. Based on the analysis results, curved and straight bridges were compared to assess the influence of the subtended curvature angle on seismic behavior. The findings indicate that, in addition to the limitations proposed by AASHTO LRFD Specifications regarding the subtended angle of curved bridges, a broader range of parametric variations should be considered in the seismic design of such structures.