A DOUBLE-SPRING MODEL FOR LONGITUDINAL DISPLACEMENT-RESISTANCE RELATIONSHIP OF FASTENERS IN RAIL-BRIDGE INTERACTION ANALYSIS

The rail-bridge nonlinear interaction problem for urban rail transit system is investigated with loading histories considered. A double-spring model is proposed to account for the change of resistance properties of the fastener under various load cases, based on the longitudinal displacement and resistance experiments for the DT-2 fastener. This model is then applied to rail-bridge interaction calculation in a case study and the results are compared with traditional linear superposition method. It is found that the traditional method is conservative for the internal forces of the rails but unsafe for the rail-bridge relative displacements and longitudinal displacements of piers.