Study On Collision Effect Of Skew Girder Bridge Under Near-fault Earthquake

Although scholars at home and abroad have done some research on the impact of the collision effect between the girders and adjacent structures of skew girder bridges under earthquake,the research on the collision effect of skew bridges is mostly focused on the far-field ground motions,and the research on the collision effect of skew bridges under near-fault earthquake is less.The characteristics of near-fault earthquakes,which are different from those of far-field earthquakes,such as impulse effect and high wall effect,may cause different hazards to skew girder bridges near faults from those predicted by seismic design codes.Therefore,the explicit dynamic analysis method was used to establish simply-supported skew girder bridge models in this paper.By means of numerical simulation and orthogonal analysis,the law and characteristics of collision effect of skew girder bridge under near-fault ground motion were studied.The main work and conclusions are as follows:(1)Based on orthogonal test method,16 single-span skew girder bridges without abutments were established by explicit dynamic analysis method.The influence of structural parameters on seismic response of girders without considering collision effect was systematically discussed,and the influence of near-fault seismic characteristics was discussed to clarify the key influence characteristics.On this basis,the seismic response of the optimal combination of structural parameters generated by orthogonal analysis was studied under the key influence characteristics of near-fault ground motions.It was concluded that the non-impulsive near-fault ground motions high wall were more disadvantageous to the seismic response of single-span simply-supported skew girder bridge.Without considering the collision effect,the bridge span played a major role in the displacement of the girders under different groups of near-fault ground motions,followed by the oblique angle and the bridge deck width.Without considering the collision effect,the girders would rotate from obtuse angle to acute angle under earthquake.(2)Based on the orthogonal test method,16 single-span skew girder bridges with abutments were established by explicit dynamic analysis method.The influence of structural parameters on the collision effect of skew girder bridges was discussed systematically,and the influence of nearfault seismic characteristics was discussed to clarify the key influence characteristics.On this basis,the collision effect of the optimal combination of structural parameters generated by orthogonal analysis was studied under the key influence characteristics of near-fault ground motions.It was concluded that the non-impulsive near-fault ground motions high wall were more disadvantageous to the collision effect of single-span simply-supported skew girder bridge.Under near-fault ground motions,the bridge span had the main effect on the maximum collision force between the girder and abutment and the maximum collision force between the girder and the transverse block,followed by the oblique angle and the bridge deck width.The collision effect of single-span simplysupported skew girder bridge intensified the rotation of the girder and made it produce larger rotation angle.(3)Based on the above research,some suggestions considering the collision effect were put forward for the girder clearance,transverse block setting and support length of skew girder bridges.That could prevent or reduce the damage of skew girder bridges caused by the collision effect under near-fault ground motion.