Dynamic energy due to ultimate limit state relevant traffic scenarios may completely be dissipated by plastic deformations without failure of the bridge element. If the structure shows significant strain hardening behaviour, the maximum static effect is allowed to reach the elastic limit. This paper presents a study of the dynamic action effects on the structural behaviour of “ductile” structural bridge elements showing significant deformations in the postelastic regime. The results allow deriving dynamic amplifications factors valid for the structural safety verification at Ultimate Limit State (ULS), i.e. the dynamic amplification factor may be set to 1.0 if sufficient dissipation capacity in the structural element is identified.