AbstractUnder strong wind actions, some long-span flexible deck bridges have been observed to exhibit significant lateral vibrations. Accurate quantification of the self-excited forces induced by lateral vibration is of great significance for the evaluation of the wind-resistant performance of bridges. Three typical deck sections, including a 5:1 rectangular section, a streamlined section, and a central-slotted section, are used to comprehensively address this issue using the unsteady Reynolds-averaged Navier–Stokes simulations. The applicability of the linear analysis method for quantifying the self-excited forces is reexamined for different lateral vibration amplitudes and reduced wind speeds. The results show that the self-excited drag force induced by lateral vibration agrees well with the linear theory for the three sections. However, the self-excited lift force and torsional moment induced by lateral vibration cannot be quantified by the linear formulations. For the rectangular section, the self-excited lift force and torsional moments are much smaller than the vortex-induced counterparts. For the streamlined and central-slotted sections, the ratios of the self-excited components to the vortex-induced components are closely related to the reduced wind speed and vibration amplitude. The ratios increase with an increase in vibration amplitude and a decrease in reduced wind speed. Thus, particular attention should be paid to the self-excited lift force and torsional moment induced by lateral motions for bridge decks.