Analysis on distortion effect of box girders considering the secondary shear flow due to restrained torsion
To reveal the coupled relationship between restrained torsion and distortion of the box girders and study the influence of restrained torsion on the distortion effects,the governed differential equation for distor-tion of box girders considering the restrained torsion is established based on the distortion load induced by the secondary torsional shear flow due to restrained torsion.According to Umansky's second theory,the restrained torsional shear flow is proposed to represent the Bredt shear flow of total torque corrected by the distortion effects induced by restrained torsion.The formulas are validated using numerical results from Ansys finite ele-ment models and the energy method.Numerical results indicate that the results obtained from the two decom-position methods of restrained torsional shear flow are identical.The restrained torsional shear stresses at dif-ferent points agree well with the results calculated by the Ansys finite element method.The total normal stres-ses induced by torsion and distortion and the distortion normal stresses agree with the results obtained from the energy method calculation,with errors not exceeding 10％.It is more accurate to calculate the distortion effects in box girders considering the influence of secondary shear stress due to restrained torsion.
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