| Nowadays,a bifurcated special shaped box girder bridge is usually adopted to connect the main bridge and the ramp bridge in urban viaducts and overpasses.Generally,these bridges have variable width,slope and curvature.The stress characteristics are complex and the spatial effect is prominent for bifurcated special shaped bridges.At present,the research method of this kind of bridge is not clear.By comparing the research theories and methods of this kind of bridge,this paper uses the grillage method as a main research method on the mechanical behavior of this kind of bridge,and this study has a certain engineering significance.In this paper,a fork shaped special shaped box girder bridge in a flyover is taken as the engineering background.The main contents are as follows:1?The research theories and methods of bifurcated special shaped box girder bridges are summarized.The principle of grillage method and its numerical calculation and analysis method are expounded..2?The key points of finite element modeling of bifurcated special shaped box girders including the grid division method and element division are discussed in detail.The influence of the different division methods of box girder with different cross sections on the calculation results are studied.3?The reaction force of the support point,the deflection deformation and the stress distribution of the beam are investigated through the finite element model of a bifurcated special shaped box girder bridge.The correctness of the grillage method is verified.4?The following contents of the bifurcated special shaped box girder bridge are studied through the grillage method and finite element model:(1)ramp bridge gradient;(2)opening angle of bifurcate mouth;(3)number of diaphragms;(4)stiffness of supporting plate diaphragms;(5)structural parameters such as stiffness of connected beams.The influence of the main structural parameters on structural deformation and stress are discussed. |
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