Spatial Stress Analysis Of The Main Girder Of A Railway Extradosed Cable-stayed Bridge

In order to study the stress distribution characteristics in box girder of long-span railway extradosed cable-stayed bridges during construction and operation,taking a extradosed cablestayed bridge with main girder in single box and single room form,with prestressed concrete material under construction-Kalasuke Reservoir Bridge(140+260+140)m in Xinjiang as an example,through the finite element numerical simulation method,the following work is done:First of all,based on the background bridge,using the finite element software Midas Civil a full-bridge plane beam element model is established.The distribution of normal stress at the upper and lower edges of the main beam is analyzed when the bridge has the largest double cantilever without inclined cables,one has the largest double cantilever and one is completed.Using beam element theory to ensure the overall safety of structure during construction.Simultaneously,the obtained internal force results provide basis for application of boundary conditions of the model,which lately will be used for local stress analysis of rigid fixity joint of pylon and girder.Secondly,when the stresses on cross-sections of main girder are solved by the plane beam element model,only stress average can be obtained.Only by the average value to express some of the longitudinal stress changes in the transverse direction of the larger crosssectional stress state,the error is greater.The finite element software Midas Fea is used for the studied to establish solid element model,then it researches normal stress distribution characteristics of the upper and lower edges of the main girder during the key construction stages.Compared with the stress results obtained by the beam element model,It is pointed out some section locations only relying on the beam element model to analyze the structure when the stress deviation is large,and it explains the cause of obvious uneven distribution of longitudinal stress along these transverse sections.In addition,the distribution of lateral stress and principal stress on tower-girder fixed segment under the main force combination is studied.The stress danger range of the concrete in this area is pointed out and the improvement measures are given for construction reference.