Abstracts This paper addresses the effect of spatial variations of ground motion with different wave propagation apparent velocities in soft and medium soil, and the influence of soil–structure interaction (SSI) on the pounding response of two adjacent bridge frames. Spatial ground motion time histories are simulated according to the Japanese design spectra and an empirical coherency loss function. In order to obtain a more reliable conclusion, three sets of spatial ground motions are independently simulated for each considered case. The ensemble mean girder responses obtained from the three independent time history analyses are used for the evaluation of the gap size required to avoid pounding between the bridge girders. The pounding behaviour of girders is analysed by using a combined finite element and boundary element method. The study reveals that both the ground motion spatial variation and SSI should be considered in the analysis of pounding responses of bridge girders.