Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes.The consequences of pounding include d...Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes.The consequences of pounding include damage to piers,abutments,shear keys,bearings and restrainers,and possible collapse of deck spans.This paper investigates pounding in bridges from an analytical perspective.A simplified nonlinear model of a multiple-frame bridge is developed including the effects of inelastic frame action and nonlinear hinge behavior,to study the seismic response to longitudinal ground motion.Pounding is implemented using the contact force-based Kelvin model,as well as the momentum-based stereomechanical approach.Parameter 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.The results indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratios greater than 0.7.Impact models without energy dissipation overestimate the displacement and acceleration amplifications due 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 subjected to far field ground motion.Finally,it is shown that strength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to large acceleration pulses from near field ground motion records.展开更多
The present paper addresses the comparative study of three adjacent single-degree-of freedom structures for elastic and inelastic system with and without pounding under seismic excitations. For the gap between three a...The present paper addresses the comparative study of three adjacent single-degree-of freedom structures for elastic and inelastic system with and without pounding under seismic excitations. For the gap between three adjacent structures, the simulation is done by using linear spring element without damping. The entire numerical simulation is done in time domain by considering the inputs of four real ground motions. The results of the study show that the response of elastic system is much different to that of response of inelastic system in the absence and presence of pounding, especially in lighter or more flexible structures. Elastic structures show much severe pounding response than inelastic structures. Modeling of colliding structures behaving inelastically is really needed in order to obtain the accurate structural pounding involved response under seismic excitation.展开更多
基金Earthquake Engineering Research Centers Program of the National Science Foundation Under Award Number EEC-9701785(Mid-America Earthquake Center)
文摘Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes.The consequences of pounding include damage to piers,abutments,shear keys,bearings and restrainers,and possible collapse of deck spans.This paper investigates pounding in bridges from an analytical perspective.A simplified nonlinear model of a multiple-frame bridge is developed including the effects of inelastic frame action and nonlinear hinge behavior,to study the seismic response to longitudinal ground motion.Pounding is implemented using the contact force-based Kelvin model,as well as the momentum-based stereomechanical approach.Parameter 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.The results indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratios greater than 0.7.Impact models without energy dissipation overestimate the displacement and acceleration amplifications due 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 subjected to far field ground motion.Finally,it is shown that strength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to large acceleration pulses from near field ground motion records.
文摘The present paper addresses the comparative study of three adjacent single-degree-of freedom structures for elastic and inelastic system with and without pounding under seismic excitations. For the gap between three adjacent structures, the simulation is done by using linear spring element without damping. The entire numerical simulation is done in time domain by considering the inputs of four real ground motions. The results of the study show that the response of elastic system is much different to that of response of inelastic system in the absence and presence of pounding, especially in lighter or more flexible structures. Elastic structures show much severe pounding response than inelastic structures. Modeling of colliding structures behaving inelastically is really needed in order to obtain the accurate structural pounding involved response under seismic excitation.
