【摘要】：箱形截面在橋梁建設(shè)中被越來越多地廣泛采用，這不僅是由于箱形截面具有截面抗扭和抗彎剛度大，而且箱形截面梁具有結(jié)構(gòu)自重小等諸多的優(yōu)點(diǎn)。但是箱形梁在承受偏心荷載作用時(shí)，除了引起截面剛性扭轉(zhuǎn)外，還會(huì)產(chǎn)生截面約束扭轉(zhuǎn)，也就是畸變變形。在畸變變形中，箱形截面產(chǎn)生翹曲應(yīng)力，并且翹曲應(yīng)力在箱形梁的自身彎曲應(yīng)力中所占比例很大。因而在箱形截面梁的設(shè)計(jì)工作中，畸變效應(yīng)必須加以考慮，是不容忽視的。 箱形梁的畸變微分方程大致有兩類表達(dá)形式：一是用畸變后的扭轉(zhuǎn)角（畸變角）來表示的畸變微分方程，一類是用畸變撓度表示的畸變微分方程。本論文著重對(duì)用畸變角表示的畸變微分方程進(jìn)行了詳細(xì)的推導(dǎo)。本論文所做的工作有以下幾個(gè)方面。 首先，對(duì)箱形截面梁所承受的偏心荷載進(jìn)行分解，得到用以計(jì)算的畸變荷載，畸變荷載包含了豎向和水平兩種畸變荷載形式。并分析了箱形梁在斜支撐（三條腿）情況下，由于箱梁自重而產(chǎn)生的畸變荷載，這類畸變荷載屬于支座反力，需要單獨(dú)分析。 其次利用能量變分原理和靜力平衡法推導(dǎo)出單室矩形截面箱梁的畸變微分方程，并且對(duì)用畸變角表示的微分方程和用撓度表示的微分方程進(jìn)行了比較，得出了二者之間的相互轉(zhuǎn)換關(guān)系。箱形梁的畸變微分方程與彈性基地梁的撓曲微分方程有相似的表達(dá)式，由此可通過求解彈性基地梁的撓度來確定箱形梁的畸變角。 接著對(duì)某一單室矩形箱梁在偏心均布荷載下進(jìn)行理論計(jì)算和建模分析。利用兩種不同方法推導(dǎo)的微分方程對(duì)算例進(jìn)行計(jì)算，得到兩種不同的計(jì)算結(jié)果，再利用ANSYS的分析結(jié)果對(duì)兩者進(jìn)行比較，，從而得出利用靜力平衡法推導(dǎo)出的畸變微分方程更加精確。 最后，研究了橫隔板的設(shè)置對(duì)箱形梁畸變的影響作用。在集中偏心荷載和均布偏心荷載作用下，橫隔板的設(shè)置對(duì)箱形梁的畸變影響不同。在均布荷載作用下，橫隔板的設(shè)置對(duì)減小畸變有明顯的效果，設(shè)置一定數(shù)量的橫隔板時(shí)，就能有效地減小畸變的影響作用。但在集中荷載作用下，在集中荷載以外截面的橫隔板對(duì)集中荷載截面的畸變影響不大，只在集中荷載截面處設(shè)置橫隔板就能達(dá)到想要的效果。 目前，橋梁設(shè)計(jì)者已經(jīng)認(rèn)識(shí)到箱形梁畸變的重要性，逐步的分析和完善了箱形梁畸變效應(yīng)的影響作用。本論文中通過對(duì)單室矩形截面箱梁的畸變效應(yīng)分析，也進(jìn)一步說明了對(duì)薄壁箱梁畸變效應(yīng)進(jìn)行深入研究的必要性。
[Abstract]:Box section is more and more widely used in bridge construction, which is not only due to the torsion and bending stiffness of box section, but also to the advantages of box section beam with low structural weight and so on. However, when the box beam is subjected to eccentric load, it will not only cause the rigid torsion of the section, but also produce the section constrained torsion, that is, distortion and deformation. In the distortion deformation, the box section produces warpage stress, and the warpage stress accounts for a large proportion of the bending stress of the box beam. Therefore, in the design of box section beam, the distortion effect must be considered and can not be ignored. There are two kinds of differential equations of distortion for box beams: one is the distortion differential equation expressed by the distorted torsion angle (distortion angle); the other is the distortion differential equation expressed by the distortion deflection. In this paper, the distortion differential equation represented by distortion angle is derived in detail. The work done in this paper has the following aspects. Firstly, the eccentric load of box section beam is decomposed, and the distortion load is obtained, which includes vertical and horizontal distortion loads. The distortion load caused by the dead weight of the box girder under the condition of oblique bracing (three legs) is analyzed. This kind of distortion load belongs to the support reaction force and needs to be analyzed separately. Secondly, the differential equation of distortion of box girder with single chamber rectangular section is derived by energy variational principle and static equilibrium method, and the differential equation expressed by distortion angle is compared with the differential equation expressed by deflection. The relationship between them is obtained. The distortion differential equation of box beam is similar to that of elastic base beam, so the distortion angle of box beam can be determined by solving the deflection of elastic base beam. Then the theoretical calculation and modeling analysis of a single-chamber rectangular box girder under eccentrically distributed load are carried out. The differential equations derived by two different methods are used to calculate the numerical examples, and two different results are obtained, and then the two results are compared by using the analysis results of ANSYS. It is concluded that the distortion differential equation derived by the static equilibrium method is more accurate. Finally, the effect of the setting of transverse diaphragm on the distortion of box beam is studied. Under the action of concentrated eccentricity load and uniformly distributed eccentric load, the distortion of box beam is influenced by the setting of transverse diaphragm. Under uniform load, the setting of transverse diaphragm has obvious effect on reducing distortion. When a certain number of transverse partitions are set, the effect of distortion can be effectively reduced. However, under the action of concentrated load, the cross-spacer with cross-section outside concentrated load has little effect on the distortion of concentrated load section, and the desired effect can only be achieved by setting transverse diaphragm at the section of concentrated load. At present, bridge designers have realized the importance of box beam distortion, and gradually analyzed and improved the box beam distortion effect. In this paper, the distortion effect of single-chamber rectangular section box girder is analyzed, and the necessity of studying the distortion effect of thin-walled box girder is further explained.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U441;U448.213

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本文編號(hào)：2415471