Seismic-induced Pounding Analysis And Control Of Curved Girder Bridge

Under strong earthquake, seismic pounding is easily occurred between girder and girder or abutment of curved girder bridge. Material nonlinearity and contact nonlinearity exist in the structure during the seismic pounding. Seismic pounding may cause many bad effects, such as damage of the cross-section of the main girder, large longitudinal displacement, beam falling along the main girder, large transverse displacement and unrecoverable destruction of the bent cap and block. Because of their coupling between bending and torsion and its special arc, the study of its seismic pounding is very complex and quite rare now. A four-span curved girder bridge is used to be the engineering background. Both contact element method and explicit nonlinear analysis are applied in the article. Simplified and detailed finite element model is established. The research on collision mechanism of curved girder bridge under two ground motions which are three-dimensional is carried out, and the reasonable method of seismic pounding mitigation is mentioned according to related results. This research on seismic pounding between girder and girder or abutment in curved girder bridge is important and useful for anti-seismic design of curved girder bridge.A finite element model with pounding element of curved girder bridge is established based on the phenomenon of seismic pounding between main girder and abutment of curved girder bridge. The regulation of pounding under three-dimensional ground motion is studied with the simplified method of the contact element. Internal forces of the bottom of pier and the changing regulations of the relative displacement between main girder and pier are obtained when seismic pounding occurs. The changing regulations of displacement and internal forces on the cross beam in the end of the main girder when the seismic pounding occurs and influence factors of the collision in the end of the girder are summarized. The results show that the collision is easily occurred in curved girder bridge under ground motions, and large impact force appeared during the collision and the internal forces and displacement of the main girder increase apparently. But the collision has little effect on the longitudinal displacements and internal forces of the fixed pier.A finite solid model of curved bridge is established with explicit nonlinear analysis with interaction between the beam and abutment or block fully considered. Under three-dimensional ground motions, large collision forces are produced on the cross-section of the main beam. At the same time, the collision force changes the vibration state of the main beam nodes. Different ground motion spectrum causes different collision time and numbers of collisions. In this paper, the effects on the dynamic characteristics of curved girder bridges b> seismic pounding are explored, the collision time, collision laws and dynamic collision response are studied. Displacements and accelerations of nodes at different positions, element stress and law of the element internal forces are increased by seismic pounding, and the increasing trend is that nodes close to pounding parts is more sensitive than that node far to pounding parts. Because of the seismic pounding, there is small stress-pulse at the bottom of the bridge abutment, but the effect of the pier internal force is not obvious. Under different earthquake motions, the impact on the outside is more obvious than the inside of the abutment wall, and the destruction of the outside block is greater than the inside block. These provide scientific research information should be paid more attention when designing the seismic block.A cushion material with certain thickness is applied to reduce the impact effect of earthquake between the main beam and abutment wall and impact effects between the main beam and the two blocks. The cushioning effects of nodes acceleration, elements stress, piers moment, piers shear force, piers torsion in the different position with cushion material are discussed ad it is found that the effects of the collision force by cushion material is obvious, can reduce the total energy of the collision system, alleviating the collision oscillation propagation and seismic pounding. Generally speaking, cushion material can reduce the collision effects, especially for the inside and outside blocks which are easily damaged. The rubber cushioning material can be applied in the practical engineering of curved girdei bridges.