To investigate the local dynamic behavior of orthotropic steel bridge decks under impact loads, this paper proposed a type of combined plate-beam element for analysis of trapezoidal stiffened plate and a type of 8-nodes solid-plate element for analysis of pavement. Besides, vehicle wheel loads are supposed to be triangular loads for convenience. Then, a model experiment was conducted to verify the accuracy of the proposed approach. Finally, River-sea-through channel of Hong Kong–Zhuhai–Macao Bridge is taken as an engineering case for computation analysis. The results are compared with those from FE software ANSYS. It shows that: first, the proposed approach is both accurate and efficient; second, bridge deck pavement has the effect of both self-weight and rigidity, which requires the bridge deck pavement be considered when analyzing the mechanical properties of bridge deck structure.