Impact Factor Of Multi-latreral Supported Bridge Deck Under Vehicle Load

Bridge deck is an important part of the bridge,bearing the role of transferring the wheel load to the load-bearing component,and also main force part of the box girder.Currently in bridge design,many bridge specifications have adopted a simple or conservative method to calculate the impact factor of the bridge deck,which is not necessarily applicable to skew deck and curved deck.Therefore,it is of great importance to study the coupled vehicle-brndge vibration of bridge deck.In this paper,the bridge deck is divided into three edges supported deck,and four edges supported deck according to different boundary condition and mechanic performance.The boundary conditions of the multi-latreral supported bridge deck are determined by the finite element method,and the analysis models of different bridge deck are determined.The dynamic effect and the calculation formula of the impact factor of the multi-latreral supported rectangular bridge deck,the multi-latreral supported skew bridge deck and the multi-latreral supported curve bridge deck under the vehicle load are investigated respectively.The main research results of this paper are as follows:(1)The vertical support stiffness of the web is significantly influenced by the vertical displacement and displacement impact factor of the multi-latreral supported bridge deck,and has little influence on transverse stress and transverse bending moment and corresponding impact factor;The smaller the rotational stiffness of the web,the greater the impact factor of vertical displacement,transverse stress and transverse bending moment.(2)The grade of bridge roughness has a significant influence on the dynamic response of bridge deck.From grade B to grade C,the dynamic response of bridge deck with vertical displacement,transverse stress and transverse bending moment increases with the deterioration of the bridge deck roughness,and the corresponding impact factor also increases.(3)For rectangle bridge deck with multi-lateral supported,the impact factor of three edges is bigger than the impact factor of four edges,the three edges and four edges supported bridge deck bending moment impact factors are essentially within 0.3,which is in accordance with the specifications.(4)For the skew bridge deck with multi-latreral supported,with the increase of skew angle,first 5-order inherent frequency of bridge deck increase,the dynamic response of the three edges supported and the four edges supported decreases,the corresponding impact factor increases.The calculation formula of the impact factor of the skew bridge deck is obtained through the proportional relation between the skew bridge deck and the corresponding orthogonal bridge deck.Although the impact factor increases with the increase of the skew angle,the static load extremum decreases with the increase of the skew angle,so the impact factor is not a real increase.(5)For the curved bridge deck with multi-latreral supported,with the decrease of the radius of curvature,first 5-order inherent frequency of the bridge deck decrease,the dynamic response of the three edges surpported and the four edges supported increases,the corresponding impact factor increases.The calculation formula of the impact factor of curved bridge deck is obtained through the proportional relation between the curve deck and the corresponding orthogonal bridge deck.