板桁加劲梁抗扭惯性矩的计算方法
发布时间：2019-03-01 09:07
【摘要】：随着桥梁建设的高速发展,板桁加劲梁已成为大跨度桥梁常用的断面形式。板桁加劲梁由正交异性板和桁架组合成整体,相互协调,共同受力,具有自重轻、抗弯抗扭刚度大、抗风稳定性好、跨越能力强和施工限制少等优点。抗扭惯性矩是评价板桁加劲梁受力性能和抗风性能的重要参数之一,若能快速准确地计算出板桁加劲梁的抗扭惯性矩,尤其是对抗扭惯性矩的计算进行公式化表达,将为板桁加劲梁的概念设计提供更充分的依据,同时节约大量的计算时间和物力成本。基于公式计算得出抗扭惯性矩后,提出的板桁加劲梁简化建模方法能极大地提高计算效率,为板桁加劲梁的动静力分析带来便利。本文在总结了国内外对板桁加劲梁抗扭惯性矩的研究成果后,针对当前研究存在以及亟待解决的各种问题,结合实际工程项目做了以下工作:1)回顾已有桁架抗扭惯性矩计算方法,基于有限元软件——ANSYS建立空间桁架数值模型,验证现有计算方法的准确性。将主桁架拆分成斜腹杆体系和弦杆与竖杆构成的框架体系,基于剪切变形等效原则,斜腹杆体系的等效板厚采用已有公式计算,框架体系采用结构力学推导出的等效板厚公式计算,叠加得到新的考虑弦杆和竖杆影响的等效板厚计算公式。通过建立数值模型验证发现,新公式能够显著提高空间桁架抗扭惯性矩的计算正确性。2)基于桥面板和U肋的水平剪切变形一致的原则,改进了正交异性板的等效板厚计算方法。基于薄壁梁理论,推导出不同类型板桁加劲梁抗扭惯性矩的计算公式。建立精细化数值模型,验证了公式的正确性。基于推导出的公式,分析各参数对抗扭惯性矩的影响程度和趋势,为加劲梁的概念设计提供依据。研究发现,板桁加劲梁的斜腹杆和弦杆之间,存在一个最优夹角使其抗扭惯性矩最大。3)逆向利用抗扭惯性矩的计算方法,基于有限元软件ANSYS提出了桥面系的交叉梁简化建模方法。通过建立精细化模型进行对比验证,该简化建模方法具有较高的准确性。
[Abstract]:With the rapid development of bridge construction, slab truss stiffening beam has become a common cross-section form of long-span bridges. The plate truss stiffened beam is composed of orthotropic plates and trusses. It is compatible with each other and subjected to force together. It has the advantages of light gravity, large flexural and torsional stiffness, good wind stability, strong span ability and few construction restrictions. Torsional inertia moment is one of the important parameters to evaluate the mechanical and wind resistance performance of plate truss stiffened beam. If the torsional inertia moment of plate truss stiffened beam can be calculated quickly and accurately, especially the calculation of anti-torsional inertia moment can be formulated. It will provide a fuller basis for the conceptual design of plate truss stiffened beams, and save a great deal of calculation time and material cost at the same time. Based on the formula, the simplified modeling method of plate truss stiffened beam can greatly improve the calculation efficiency and facilitate the dynamic and static analysis of plate truss stiffened beam. After summarizing the research results of torsional moment of inertia of plate truss stiffened beams at home and abroad, this paper aims at the problems existing in the current research and the problems that need to be solved urgently. The main work of this paper is as follows: 1) the existing methods for calculating torsional moment of truss are reviewed, and the numerical model of space truss is established based on finite element software-ANSYS, and the accuracy of the existing methods is verified. The main truss is divided into oblique web system and frame system composed of chord and vertical bar. Based on the equivalent principle of shear deformation, the equivalent plate thickness of oblique web system is calculated by the existing formula. The equivalent plate thickness formula derived from structural mechanics is used to calculate the equivalent plate thickness of the frame system, and a new equivalent plate thickness formula considering the influence of chord and vertical bar is obtained. Through the establishment of the numerical model, it is found that the new formula can significantly improve the accuracy of the calculation of the torsional moment of inertia of the space truss. 2) based on the principle that the horizontal shear deformation of the bridge deck and U-rib is the same. The calculation method of the equivalent thickness of orthotropic plate is improved. Based on the theory of thin-walled beam, the formulas for calculating the moment of inertia of different types of plate truss stiffened beams are derived. A fine numerical model is established to verify the correctness of the formula. Based on the derived formula, the influence degree and trend of each parameter on torsional moment of inertia are analyzed, which provides the basis for the conceptual design of stiffened beam. It is found that there is an optimal angle between the diagonal web and the chord of the plate truss stiffener to maximize the moment of inertia. 3) the inverse calculation method of the moment of inertia of the plate truss stiffened beam by using the anti-torsion moment. Based on the finite element software ANSYS, a simplified modeling method for cross-beam of bridge deck system is proposed. It is proved that the simplified modeling method has high accuracy by establishing a fine model.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441
本文编号：2432284
[Abstract]:With the rapid development of bridge construction, slab truss stiffening beam has become a common cross-section form of long-span bridges. The plate truss stiffened beam is composed of orthotropic plates and trusses. It is compatible with each other and subjected to force together. It has the advantages of light gravity, large flexural and torsional stiffness, good wind stability, strong span ability and few construction restrictions. Torsional inertia moment is one of the important parameters to evaluate the mechanical and wind resistance performance of plate truss stiffened beam. If the torsional inertia moment of plate truss stiffened beam can be calculated quickly and accurately, especially the calculation of anti-torsional inertia moment can be formulated. It will provide a fuller basis for the conceptual design of plate truss stiffened beams, and save a great deal of calculation time and material cost at the same time. Based on the formula, the simplified modeling method of plate truss stiffened beam can greatly improve the calculation efficiency and facilitate the dynamic and static analysis of plate truss stiffened beam. After summarizing the research results of torsional moment of inertia of plate truss stiffened beams at home and abroad, this paper aims at the problems existing in the current research and the problems that need to be solved urgently. The main work of this paper is as follows: 1) the existing methods for calculating torsional moment of truss are reviewed, and the numerical model of space truss is established based on finite element software-ANSYS, and the accuracy of the existing methods is verified. The main truss is divided into oblique web system and frame system composed of chord and vertical bar. Based on the equivalent principle of shear deformation, the equivalent plate thickness of oblique web system is calculated by the existing formula. The equivalent plate thickness formula derived from structural mechanics is used to calculate the equivalent plate thickness of the frame system, and a new equivalent plate thickness formula considering the influence of chord and vertical bar is obtained. Through the establishment of the numerical model, it is found that the new formula can significantly improve the accuracy of the calculation of the torsional moment of inertia of the space truss. 2) based on the principle that the horizontal shear deformation of the bridge deck and U-rib is the same. The calculation method of the equivalent thickness of orthotropic plate is improved. Based on the theory of thin-walled beam, the formulas for calculating the moment of inertia of different types of plate truss stiffened beams are derived. A fine numerical model is established to verify the correctness of the formula. Based on the derived formula, the influence degree and trend of each parameter on torsional moment of inertia are analyzed, which provides the basis for the conceptual design of stiffened beam. It is found that there is an optimal angle between the diagonal web and the chord of the plate truss stiffener to maximize the moment of inertia. 3) the inverse calculation method of the moment of inertia of the plate truss stiffened beam by using the anti-torsion moment. Based on the finite element software ANSYS, a simplified modeling method for cross-beam of bridge deck system is proposed. It is proved that the simplified modeling method has high accuracy by establishing a fine model.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441
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