Research On Deck Rotation Of Simply Supported Skew Girder Bridge Under Earthquake

With the rapid development of China's urban road,highway and railway,a large number of skew bridges appear.Due to the special structure of the skew bridge,it is more likely to suffer damage when compared with the orthogonal bridge in the earthquake.On the basis of the research status of skew bridge,in this paper,the modle of three span simply supported skew bridge is built,the earthquake response analysis is conducted,and the influence parameters is studied.The main work carried out in this paper is as follows:(1)Based on the seismic damage data at home and abroad,combining with the seismic damage statistics of skew bridges in Wenchuan earthquake,the difference between the seismic damage of the skew bridge and the orthogonal bridge is compared,the characteristics of earthquake damage of skew bridges are summarized;(2)The current research status about design methods of skew bridges at home and abroad is introduced.The mechanism of the seismic damage of skew bridge deck-rotation is studied,which is remarkably different from that of the cross bridge;(3)The simulation of skew girder bridge superstructure,bearing pier and abutment foundation and collision are described.The theories and methods of structural time history analysis are summarized,and the selected ground motion is introduced;(4)A typical skew bridge model is established to compare the difference between the dynamic characteristics of the skew bridge and the orthogonal bridge.By modal analysis,the influence of support condition symmetry,skew angle and bearing stiffness on the dynamic characteristics of the skew girder bridge are studied.Seismic response analysis of skew girder bridges is carried out without considering collision effect.Results show: Rotation around the vertical axis appears in the low-order vibration mode of the skew bridge;When the beam end support is symmetrical,the decks does not rotate,and this is not affected by the change of ground motion acceleration peak value,input direction,skew angle and bearing stiffness.Otherwise,it is affected sharply by them;(5)A series of finite element model is established and the nonlinear history analysis,the influences of the support condition symmetry,peak value of ground motion acceleration,the input direction,skew angle,a telescopic seam width,transverse block initial clearance on the skew beam bridge seismic response are studied.It is found that the longitudinal impact of the superstructure is the important reason for the rotation of the bridge deck.The transverse block can limit the displacement of the main beam,but it can significantly increase the torque at the bottom of the pier.