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英文原文2Seismic Behavior and Capacity/Demand Analyses of a SimplySupported MultiSpan Precast BridgeNasim Shatarat and Adel Assaf International Journal of Applied Science, Engineering and Technology 5:4 2009ACOMMONLY used type of bridges in Washington State (WA) in the 1950’s and 1960’s is MultiSpanSimplySupported (MSSS) precast system. This system was proven at the time to be easy to be designed and to be constructed. The designers used a predesigned tabulated set of bridge ponents, where the superstructure and the substructure ponents are selected based on certain global characteristics and dimensions of the bridge such as, height of the columns, roadway width, bent skewness and span length. The predesigned bridges always hold the same assumptions in terms of material strength. Then, modification to footings or other ponents might be introduced based on site Conditions.The superstructure of these bridges consist of prestressed concrete girders that are supported by concrete bents, which usually consist of a cap beam that is 3ft x ft ( x m) supported by a number of circular columns, typically 3 ft ( m). The number of the columns depends on the bridge skewness and the roadway width. Spread footings or footings on timber piles were the mon footing systems used.The MSSS prestressed concrete bridges built in Washington State in the 1960’s were designed with little or no attention to seismic forces. Seismic provisions that guarantee appropriate ductility and acceptable seismic performance such as confinement, rebar splice length and girder seatlength were not considered. Only couple of girder stops where used tosupport the bridge deck against accidental lateral movement. Longitudinal restrainers were not monly provided, as the contact length between the girders and the top of the cap beam was assumed to be sufficient to acmodate longitudinal displacement. Abutments were typically seattype supported on strip footing or timber piles. Recently, Washington State