Analysis Of The Influence Of Longitudinal And Transverse Stiffeners On The Rigidity Torsional Performance Of Single Box And Single Chamber Steel Box Girder

Due to the superior performance of box girder,thin-walled steel box girder bridges have occupied a large proportion in all kinds of structural Bridges in recent years.At present,many scholars at home and abroad have done a lot of in-depth research on the restrained torsion and distortion effect of box girder,but not enough attention has been paid to the rigid torsion effect of steel box girder with longitudinal and transverse stiffeners.The steel box girder is obviously different from the concrete box girder.The diaphragm,longitudinal stiffener and transverse stiffener in the steel box girder have great influence on the torsion of the box girder.It is necessary to systematically study the torsion effect of steel box girder.This paper mainly studies the rigidity torsion effect of ribbed steel box girder.The main research contents and conclusions are as follows:(1)Based on the second theory of uwe,the theoretical formula of the rigid torsional stress of steel box girder with longitudinal stiffener is obtained,and the differential equation of the constrained torsional control is solved by the initial parameter method.The theoretical formula of the rigid torsional stress of simply supported steel box girder under the action of concentrated torque is derived.(2)When analyzing the single-box single-chamber steel box girder with longitudinal stiffeners under the same torque and support mode,it can be seen that the torsion angle and constrained torsional double moments are reduced compared to the case without stiffeners.5.5% and 4.75%.For the rigid torsion of the steel box girder,from the perspective of the initial parameters of the structure,it is shown that the addition of longitudinal stiffeners can improve its torsional performance.(3)Combining with the calculation example of steel box girder,the theoretical formula is used to calculate the stress of the mid-span section of simply supported steel box girder under the action of concentrated torque.The three-dimensional shell element model of simply supported steel box girder is established with ANSYS,and the numerical solution of rigid torsion of steel box girder is obtained by controlling the deformation of the periphery of the section when the steel box girder is twisted.By comparing the finite element numerical solution and analytical solution,the regularity is consistent and the data is in good agreement,which indicates the feasibility of the method.(4)Combined with the calculation example in this paper,the influence of section geometry characteristics on the constraint torsion effect of single box and single chamber steel box girder is studied.The thickness of the bottom plate has a greater influence on the restrained torsion stress than that of the top plate and the web,and the thickness of the web has a greater influence on the restrained torsion shear stress than that of the top plate and the bottom plate.The geometric characteristics of the single-box single-chamber steel box girderwith longitudinal stiffeners,such as height,thickness,spacing and other factors have a certain degree of influence on the torsional performance of the steel box girder.(5)The normal stress of the mid-span section after adding longitudinal stiffeners in the finite element is less than that under the same conditions without longitudinal stiffeners;the installation of transverse stiffeners has a certain effect on the torsional performance of the steel box girder,Using finite element method,the effect of the location of the lateral stiffeners and the spacing of the bottom stiffeners on the constrained torsional stress of the steel box girder was studied.