The purpose of this paper is to propose simulated earthquake ground motions for the structural design of buildings subjected to a surface rupture with a large permanent displacement (fling step). The seismic waveform is synthesized as a pulse, with the Fourier amplitude based on the ω1 model and the Fourier phase consisting of uniform phase differences. It is shown that the time history of the displacement, obtained by integrating the synthesized wave, can be interpreted as the source time function associated with fling step, which is characterized by a large and permanent displacement of the ground in one direction. Moreover, it is demonstrated that the dynamic behavior of buildings is properly evaluated when the synthesized wave is used as input. The average slip velocity of fling step will provide an effective index for the dynamic analysis of structures.
