Analysis Of Shear Lag Effect On Steel Box Girder In Cable-stayed Bridge With Single Cable Plane

Streamlined flat steel box girder is becoming the most popular in the long span cable-stayed bridges reeently, for its light weight, good performance of bending, torsion and alsowind resistanee. As this type of structure has very thin slabs and smaller height to width ratio，the shear lag effect in it is more notable. On the basis of previous researehes, the shear lageffect in the flat steel box girder of four-room of the single cable plane cable-stayed bridge isstudied in this essay as take the Guangzhou Nansha Phoenix First bridge for engineeringbackground.(1) Describes three-bar stimulation method for analyzing the shear lag effect of the singlerectangular section with four cells.The flat box section is simplified to a standardized form，sothat the shear lag effect in indeterminate main girder of a cable-stayed bridge can bearingcompression and flexural moment can be analyzed by superposition or dismembermentprinciple.The comparisons with FEA results show that stresses of the flat steel box girder of acable-stayed bridge can be approximately calculated by the above method.(2) By means of finite element analysis software ANSYS program, establish finiteelement solid model of Nansha Phoenix First Bridge, analysis and calculate the structurestress in different construction stages, and then obtaine stress distribution of the girder roofand floor in the transverse direction girder longitudinal shear lag effect distribution bydifferent construction stages. Finally, analysis the steel box section shear lag effect combinedwith MIDAS plane stress calculation results.(3) The parametric analysis is carried out by the model using FEM, including steel boxgirder aspect ratio of width to span ratio, transverse loading position, spacing and thickness ofthe diaphragm, mediastinal plate thickness, type of load and other factors. The results showedthat there are still lag issues when cable tension of axial component Transmitted to the entiremain beam section. Furthermore, cross-aspect ratio, aspect ratio of the shear lag coefficienttheimpact is remarkable. Type of load and lateral load acting position, with or without thediaphragm shear lag effect in box girder have a certain impact. In addition, comparison of theconstruction phase cross-section transverse normal stress data and finite element analysisresults are similar, the same trend to verify the finite element analysis is correct.