AbstractThe appropriate estimation of displacements is crucial in performance-based design. Among the options to assess deformation demands, Nonlinear Time History Analysis (NLTHA) is the most sophisticated. However, previous research has shown that NLTHA is sensitive to the viscous damping model definition, and there is substantial disagreement in the engineering community regarding damping model choices. Thus, the goal of this paper is to show the impact of viscous damping model assumptions on the nonlinear response of bridges. A displacement sensitivity study was conducted on several multi-span bridges using various viscous damping models and earthquake records. The results indicate that the mean displacement varies as a function of the displacement ductility level and damping model. In order of ascending displacement demand, the Wilson-Penzien model had the lowest demands followed by the Rayleigh-Initial stiffness, Mass proportional, Rayleigh-Tangent stiffness, Tangent stiffness proportional damping, and Zero-damping. Also, this paper proposes a new viscous damping model. We expect these findings to help practitioners understand the implications of the choice of the damping model and guide the analyst when selecting damping parameters.