Force Analysis Of Super-wide Steel Girder Boxes Of Two-tower Single Cable Plane Cable-stayed Bridge

The Fourth Beijiang Bridge is a long-span single cable-plane cable-stayed bridge with a main span of 218 m.The height of the main steel box girder is 4m,and the width of the steel box is 43 m.The super width of the girder indicates that,when the bridge is under partial loading,a significant torsional distor tion is generated.Moreover,since the main girder is relatively wide,8 supports are fixed in two rows,which may cause uneven distribution of support reaction and influence the stability of the structure.In addition,the cables are fixed in the area clo se to the center of main girder,therefore the steel-UHPC hybrid deck and the board flange steel box girder can be easily influence by the reaction.Based on project of the Fourth Beijiang Bridge,this dissertation studied the distortion of the super-wide steel box girder,the redistribution of support reaction caused by main girder distortion and multiple support arrangement under different working condition of single cable-plane cable-stayed bridge,and the mechanical analysis of super-wide steel-UHPC composite bridge deck.In this dissertation,ANSYS is applied to model the bridge structure,and then researches on the top and bottom plane reaction and the torsional distortion reaction of 4 key sections are conducted under different working conditions(par tial loading,symmetric loading and wind loading).The first two sections are 21 m far away from the root of tower and the reminding sections are located in the 1/4 of main span.Based on our research,the reactions of all sections under different condition s meet the requirements.Two rows of supports were arranged on every tower of the Fourth Beijiang Bridge and the stress conditions of supports are complicated.In order to analyze the rearrangement of support reaction of lower tower base under partial load ing,different working condition was set in service stage as well as maximum cantilever stage in the ANSYS model.The A-class steel box girder close to the root of tower and build its model with much more details to analyze the reaction of the steel-UHPC hybrid board is selected.In this experiment,12 working conditions are setted,and the results show that the reactions of all sections under these working conditions meet the requirements.Moreover,a conclusion can be easily made that steel-UHPC hybrid girder is capable of improving the reaction condition of the sections.