Research on proportion of constrained torsion in mixed torsion of thin-walled bar
In order to determine the proportional relationship between pure torsion and constrained torsion of thin-walled bar under mixed torsion with different boundary conditions,firstly,the mixed torsion differential equation was established based on Vlasov thin-walled structure theory.The proportion formula for constrained torsion of thin-walled bar under concentrated torque and uniform torque was derived using the initial parameter method.Based on simply supported boundary,the influence of boundary conditions on the proportion of constrained torsion was analyzed by introducing the constraint stiffness coefficient β.Then,the formula was verified using the finite element software ABAQUS.Finally,the calculation formula for the constrained torsion characteristic coefficient κ of the common section of steel bridge was provided,and the distribution range of κ for the steel-concrete composite twin I-girder bridge and the steel box girder bridge were counted.The results show that the derived formula for constrained torsion ratio agrees well with the calculation results obtained from ABAQUS.The proportion of constrained torsion is affected by the section's κ and boundary conditions.A larger κ corresponds to a smaller proportion of constraint torsion,and the influence of boundary conditions on the proportion of constraint torsion changes with κ.The β can effectively characterize the influence of boundary conditions on the proportion of constraint torsion.In simplified analysis,when 0＜κ≤0.6,the influence of pure torsion can be disregarded,and the analysis can focus solely on constrained torsion.When κ exceeds 40,the impact of constrained torsion can be neglected,and the analysis can be based solely on pure torsion.In the case where 0.6＜κ＜40,a mixed torsion analysis is required.The calculated κ range for the steel-concrete composite twin I-girder bridge is 0.71 to 1.58,and the κ for the steel box beam bridge is greater than 39.8 tabs,10 figs,26 refs.
NETL
NSTL
万方数据
