Force Analysis On Large Span Stiff Skeleton Concrete Arch Bridge During Segment Construction

To study the mechanical behavior and bearing capacity during the construction process of the stiff skeleton arch bridge,the Jinyang across Jinsha River bridge is taken as the research object.The large finite element software Midas Civil is applied to carry out the stress analysis to the bridge construction process.In view of the three main stages of the construction process of the stiff skeleton arch bridge,namely the stiff skeleton construction stage,the outsourced concrete construction stage and the completed bridge stage,the force analysis is taken into action and the following conclusions are obtained.(1)The compressive stress of the steel pipes increases gradually at the stage of stiff skeleton installation,reaching at about 150 MPa,which further rises during the construction stage of the outsourced concrete casting,reaching about 300 MPa at the phase of the second loop closure.(2)The outsourced concrete is only subjected to compressive stress which increase gradually during the whole construction process,that the stress of the upper plate reaches around 6 MPa,the lower plate about 15 MPa,the web about 10 MPa at the phase of the second loop closure.(3)The deformation of the steel skeleton during the concrete pouring process is large enough to further influence the line shape of the completed bridge in an obvious way.(4)The shift pouring sequence of internal pouring concrete have barely no influence on the stress and deformation of the structure,while altering the longitudinal length of the outsourced concrete construction will increase the stress.(5)According to the stress superposition methodology the stress of the steel pipe would exceed the allowable stress value or even yield during the construction.The calculation of the bearing capacity of the control section shows that the affluence coefficient of bearing capacity of the arch foot section is 2.12,the 1/4 section 1.77,the 3/8 section 1.65 and the vault section 1.34.It could be told that the stress superposition methodology underestimate the bearing capacity of the bridge.