Abstarct: Significance of lifelines like roads, bridges, pipelines and tunnels emphasize on more accurate design of these structures. In conventional methods of seismic analysis of bridges, it is assumed that during earthquake, different piers are subjected to the same support excitation. However, this assumption is not true for long bridges and different supports undergo different excitations. This difference in excitations is attributed to the time delay in arrival of seismic waves as well as changes in seismic waves while passing through soil laxyers. The differences in support excitation of different piers, may lead to amplify stress and displacement of bridges. In this thesis, the generation of artificial time history acceleration at bridge supports and the effect of multi support excitation on response of bridges are studied.