Analysis The Shear Lag Effect During The Construction Process Of Cantilever Box Girder Bridge Based On Girder Plate Element Method

The effect of shear lag as a common phenomenon in the thin-walled box girder structures has attracted the attention wildly.It will lead to less calculation if being ignored,which will be harmful to structural safety.Although the influence factors of the shear lag effect have been studied,the structural stress was ensured by the modification of the structural cross section.However,the shear lag effect of the thin-walled box girder was mostly studied.There was little research on the effect of lag.Considering that the largest stress was on the roots during the process of construction,this paper considered the root section under any condition of stress changes.The predecessors’ study on the shear lag effect of thin-walled box girder was summarized in this paper.the stress state of cantilever box girder structure under various loads was analyzed to study the variation law of shear lag effect.In this paper,when the stress of cantilever bridge was analyzed,it was found that the different arrangement of steel beam had a great influence on the structural stress and was described by MIDAS /FEA software.This study was carried out through theoretical analysis,software simulation,and practical bridge stress monitoring.The specific research content was as follows:Firstly,in the aspect of theory,the theory of plate element method was introduced,and the stress differential equation of box section of cantilever beam under various load was calculated by this theory.As the finite element developed,the structural force analysis was separated from the difficult situation of solving analytic solutions by theoretical method,and the large scale and high efficiency environment was solved by using theoretical analysis and finite element method to solve numerical solution.and beam element plate method was to use this idea to solve the structural stress problem.In this paper,MATLAB software was used to solve the stress differential equation calculated by plate element method.Secondly,the use of three kinds of finite element software analyzed cantilever structure stress state in the finite element software simulation.First of all,ANSYS modeling techniques and simplified methods were explained by ANSYS finite element analysis software.Then the same structure model was established based on MIDAS/FEAsoftware,and talk about the comparison and analysis on the structure stress state with the two software.Finally the results of actual were compared with the plane cross-section assumption used of MIDAS/CIVIL software.Thirdly,in the aspect of engineering test,this paper relied on the construction project of Shuikou waterway Bridge to monitor the stress of the main section of the main bridge box girder.Due to the many factors influencing the actual engineering stress measurement,some methods to deal with data were given in this paper.Finally,the numerical solution of the plate element method was analyzed,the calculation results of the three finite element software and the actual engineering monitoring stress data were analyzed.The results showed that the plate element method and the finite element method were similar and the results were larger than the measured stress value.The plate element method had high accuracy and credibility in analyzing the shear lag effect of the cantilever structure...