板桁加勁梁抗扭慣性矩的計算方法
發(fā)布時間：2019-03-01 09:07
【摘要】：隨著橋梁建設(shè)的高速發(fā)展,板桁加勁梁已成為大跨度橋梁常用的斷面形式。板桁加勁梁由正交異性板和桁架組合成整體,相互協(xié)調(diào),共同受力,具有自重輕、抗彎抗扭剛度大、抗風穩(wěn)定性好、跨越能力強和施工限制少等優(yōu)點�？古T性矩是評價板桁加勁梁受力性能和抗風性能的重要參數(shù)之一,若能快速準確地計算出板桁加勁梁的抗扭慣性矩,尤其是對抗扭慣性矩的計算進行公式化表達,將為板桁加勁梁的概念設(shè)計提供更充分的依據(jù),同時節(jié)約大量的計算時間和物力成本�；诠接嬎愕贸隹古T性矩后,提出的板桁加勁梁簡化建模方法能極大地提高計算效率,為板桁加勁梁的動靜力分析帶來便利。本文在總結(jié)了國內(nèi)外對板桁加勁梁抗扭慣性矩的研究成果后,針對當前研究存在以及亟待解決的各種問題,結(jié)合實際工程項目做了以下工作:1)回顧已有桁架抗扭慣性矩計算方法,基于有限元軟件——ANSYS建立空間桁架數(shù)值模型,驗證現(xiàn)有計算方法的準確性。將主桁架拆分成斜腹桿體系和弦桿與豎桿構(gòu)成的框架體系,基于剪切變形等效原則,斜腹桿體系的等效板厚采用已有公式計算,框架體系采用結(jié)構(gòu)力學推導出的等效板厚公式計算,疊加得到新的考慮弦桿和豎桿影響的等效板厚計算公式。通過建立數(shù)值模型驗證發(fā)現(xiàn),新公式能夠顯著提高空間桁架抗扭慣性矩的計算正確性。2)基于橋面板和U肋的水平剪切變形一致的原則,改進了正交異性板的等效板厚計算方法�；诒”诹豪碚�,推導出不同類型板桁加勁梁抗扭慣性矩的計算公式。建立精細化數(shù)值模型,驗證了公式的正確性�；谕茖С龅墓�,分析各參數(shù)對抗扭慣性矩的影響程度和趨勢,為加勁梁的概念設(shè)計提供依據(jù)。研究發(fā)現(xiàn),板桁加勁梁的斜腹桿和弦桿之間,存在一個最優(yōu)夾角使其抗扭慣性矩最大。3)逆向利用抗扭慣性矩的計算方法,基于有限元軟件ANSYS提出了橋面系的交叉梁簡化建模方法。通過建立精細化模型進行對比驗證,該簡化建模方法具有較高的準確性。
[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.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U441
本文編號：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.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U441
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