Abstract: For the seismic response analysis of long-spanstructures, the characteristics of the response spectrummethod, the random vibration method and the time historymethod are compared in this paper. It is found that thespatially varying effects of the ground motions, especiallythe wave passage effect, have great influences on the dynamicresponses of long-span structures. For seismic analysis ofmulti-degrees-of-freedom, multiply supported structuressubjected to spatially varying ground motions, the responsespectrum method is difficult to implement, while the randomvibration method has great advantages. For nonlinear seismicanalysis of long-span structures under very strong groundmotions, the time history method is still the preferredapproach nowadays.