The objective of this research project is to understand the behavior of seat type or free- standing abutments and their interaction with the bridge deck under seismic loading conditions. In this project a recently developed rigid-plastic model to predict abutment movements will be modified. The modified model will be capable of treating the translation and tilting of the abutment in a coupled manner and will account for movements prior to yielding. Such capabilities will be verified using centrifuge model tests. In the second phase of the study, the consequences of abutment gap closure relative to the bridge response will be investigated. This will involve the determination of the dynamic abutment-deck interaction forces during the excitation. Such forces are necessary to study the overall response of the bridge deck and to design the "soft-top" abutments. Parametric analysis to evaluate the relative importance of the factors that govern abutment behavior will then be performed. This analysis will lead to a better understanding of the abutment behavior and will result in a more rational and improved design in which abutment- deck interaction can be realistically quantified and accounted for in design.
