This research thesis is product of a joint study between the Ministry of Transportation and Infrastructure (BCMoT) and the University of British Columbia (UBC) to evaluate the effect of Embankment-Abutment-Structure Interaction (EASI) in the estimation of seismic demands of Integral Abutment Bridges (IABs). IABs consist of a continuous concrete deck integrated with abutments supported on flexible foundations. These structures have become very popular due to the elimination of costly and maintenance prone expansion joints and bearings. Analytical studies and strong-motion earthquake data have shown that the seismic response of the approach embankments in the far field affects the response of IABs. However, current seismic analysis procedures neglect the far-field embankment response because of the complexity in modeling this type of dynamic interaction. Therefore, a simple and accurate model that allows bridge designers to include EASI in the calculation of the seismic demands of IABs is needed. This thesis develops a simple dynamic model, called 3M-EASI, for calculating the seismic response of IABs taking into account EASI. The proposed model consists of two far-field embankment components connected to the bridge structure component by spring-dashpot elements that represent the near-field components. The main contribution of this thesis is the development of the far-field embankment component using equivalent-linear analysis. The 3M-EASI model was verified with time-history analyses of 2D continuum soil finite element models of full-height IABs using the computer program ABAQUS. The analyses indicated that the far-field embankment response affects the response of IABs if the following conditions act simultaneously: (a) the near-field stiffness is greater than 0.4 times the bridge stiffness, and (b) the period of the far-field embankment components is longer than 0.7 times the period of the bridge-near-field system. The 3M-EASI model is shown to be rational, accurate, computationally efficient, and easy to implement in bridge design.