Study On The Structure Of Irregular Continuous Box Girder Bridge Based On The Grillage Analysis Method

To make the structure line smooth in the highway and urban interchange,it is necessary to set up the variable width bridge as the transition bridge between main bridge and ramp.Due to the particularity of its geometric structure,the variable width box girder bridge is more complex than the ordinary box girder bridge,spatial bearing performance characteristic of this bridge is very prominent,the complexity of its structure and the force adds some difficulties to the design.However,at present,the research on the variable width and irregular bridge mainly lies in the calculation method and the model test.The research on the mechanical characteristics of the bridge is few.Therefore,it is of great theoretical value and practical significance to study the mechanical properties of the bridge structure.Based on number five left part of interchange as the engineering background,the main contents and conclusions are as follows:1.The thesis systematically expounds the basic principle of grillage method,and summarizes the methods and means of different grillage division of the box girder structure,through the analysis of the actual modeling project,discusses the related problems of finite element modeling of grillage method,summarizes some key points of variable beam analysis of special-shaped bridge.2.Taken the plate element model as the reference,the comparative analysis is carried out from the reaction force of the support,deflection and stress of the main beam under the typical working conditions.The results show that the calculation results of the grillage model are consistent with that of the plate element model,which could meet the engineering design requirements.3.In order to investigate the influence of the bearing arrangement on the structural mechanical properties,the differences between the three kinds of support arrangement scheme in the internal force of the main beam and the support reaction force are analyzed and compared,the change rule of the bearing arrangement to the structural stress is obtained,some suggestions are given for the reasonable arrangement of the special-shaped bridge bearings.4.Through an example of engineering,the effects of the stiffness of the fulcrum beam and cross diaphragm setting on the mechanical behavior of the special-shaped bridge with variable width are explored.According to the law of mechanical behavior,the suggestions of layout of diaphragm of widened irregular bridge are given;which provide some references for the design of the same type bridge.5.According to the mechanical properties of variable width heterotypic continuous box girder bridge and the grillage theory research,the structural load test is launched.By comparing theoretical results with the actual measured data,the rationality of the model and the stiffness calculation is verified,which provides advice for loading test for bridge of the same type.