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| Analysis on restrained torsion of continuous box girder bridge with variable section under lane load |
| Received:August 15, 2023 Revised:September 20, 2023 |
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| DOI：10.7511/jslx20230815002 |
| KeyWord:thin-walled box girder restrained torsion stiffness matrix secondary shear stress torsional shear stress stress amplification factor |
| Author | Institution |
| 尉浩浩 |
中国电建集团西北勘测设计研究院有限公司, 西安 |
| 张和 |
中国电建集团西北勘测设计研究院有限公司, 西安 |
| 何昊 |
兰州职业技术学院 后勤基建处, 兰州 |
| 王磊 |
中国电建集团西北勘测设计研究院有限公司, 西安 |
| 刘志 |
中国电建集团西北勘测设计研究院有限公司, 西安 |
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| Abstract: |
| In order to analyze the effect of the constrained torsion on the section stress of a box beam,based on the initial parametric solution of the restrained torsion differential equation of the box girder,the initial parametric analysis formula of free and secondary torques is derived.According to Umansky's Second Theory and the box girder element,the element stiffness matrix,calculation matrix of free torque and secondary torque and the equivalent node load column vector are derived by introducing the box girder element with torsion angle and generalized warping displacement as node displacements.The finite element program coded in Fortran Language is applied to analyze the constrained torsion effect of continuous box girder bridges with variable sections.The program is also used to calculate the internal force and displacement of a three-span continuous box girder bridge with variable sections under the most unfavorable bimoment loading mode.The results show that the ratio of the secondary shear stress to the torsional shear stress caused by the constrained torsion effect reaches its peak on the webs.It reaches 35.66% and 68.23% respectively on the fulcrum section and the concentrated load section while it is not more than 2.23% on the rest of sections.Along the longitudinal bridge,the peak values of the normal stress and shear stress amplification factor appear at the fulcrum section.For the bridge in this paper,the normal stress amplification factor ranges from 1.077 to 1.304 and the shear stress amplification factor from 1.822 to 2.667. |
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