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Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simplysupported bridges has been commonly observed in several recent earthquakes.The consequences of pounding includedamage to piers,abutments,shear keys,bearings and restrainers,and possible collapse of deck spans.This paper investigatespounding in bridges from an analytical perspective.A simplified nonlinear model of a multiple-frame bridge is developedincluding the effects of inelastic frame action and nonlinear hinge behavior,to study the seismic response to longitudinalground motion.Pounding is implemented using the contact force-based Kelvin model,as well as the momentum-basedstereomechanical approach.Parameter studies are conducted to determine the effects of frame period ratio,column hystereticbehavior,energy dissipation during impact and near source ground motions on the pounding response of the bridge.Theresults indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratiosgreater than 0.7.Impact models without energy dissipation overestimate the displacement and acceleration amplificationsdue to impact,especially for elastic behavior of the frames.Representation of stiffness degradation in bridge columns isessential in capturing the accurate response of pounding frames subjected to far field ground motion.Finally,it is shown thatstrength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to largeacceleration pulses from near field ground motion records.
Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supporteded bridges has been commonly observed in several recent earthquakes.The consequences of pounding includedamage to piers, abutments, shear keys, bearings and restrainers, and possible collapse of deck spans.This paper investigatespounding in bridges from an analytical perspective. A simplified nonlinear model of a multiple-frame bridge is developedincluding the effects of inelastic frame action and nonlinear hinge behavior, to study the seismic response to longitudinalground motion .Pounding is implemented using the contact force-based Kelvin model, as well as the momentum-basedstereomechanical approach. Parametric studies are conducted to determine the effects of frame period ratio, column hysteretic behavior, energy dissipation during impact and near source ground motions on the pounding response of the bridge.Theres indicative that pounding is most critical for highly out-of-phase frame s and is not significant for frame period ratios greater than 0.7. Impact models without energy dissipation overestimate the displacement and acceleration amplificationsdue to impact, especially for elastic behavior of the frames. Representation of stiffness degradation in bridge columns is essential in capturing the accurate response of pounding frames受到 远 场 ground motion. Finally, it is shown thatstrength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to largeacceleration pulses from near field ground motion records.