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| Torsion element and its applications of box girder based on a new generalized displacement |
| Received:May 08, 2022 Revised:July 21, 2022 |
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| DOI：10.7511/jslx20220508003 |
| KeyWord:box girder bridge restrained torsion beam segment element free warping rotation stress increase coefficient |
| Author | Institution |
| 梁永永 |
兰州交通大学 土木工程学院, 兰州 |
| 张元海 |
兰州交通大学 土木工程学院, 兰州 |
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| Abstract: |
| In order to improve the torsion analysis theory of variable-section box girder bridges, the total section rotation is decomposed into free warping rotation and constrained shear rotation.The free warping torsion rate is selected as the generalized displacement, and a torsional beam segment element with 2 nodes and 8 DOFs is proposed.Starting from the constrained differential equation torsion, the stiffness matrix and the equivalent nodal load array of the element are established.A stress increase coefficient is introduced to reflect the increasing effect of constrained torsion on elementary beam stresses.Numerical examples verify the reliability of the beam element in this paper.Finally, a three-span variable cross-section continuous box girder bridge is analyzed.The results show that the bimoment influence line is similar to the bending moment influence line, and the maximum stress is smaller when the most unfavorable load is loaded according to the bimoment influence line.The extreme value of the stress increase coefficient in the concentrated load action section occurs at the intersection of the web and the top plate.When using the offset load amplification coefficient to consider the additional effect of torsion, it is not appropriate to consider the beam section area where the bending normal stress is small and the warping normal stress has an extreme value. |