超大跨径UHPC连续箱梁桥扭转畸变效应研究

发布时间：2019-03-16 17:16

【摘要】：超大跨径单向预应力UHPC连续薄壁箱梁桥是利用UHPC材料的优良抗压、抗拉性能,采用薄壁型结构、布置密集横的隔板箱梁以及一部分体外预应力三部分相结合的一种新型连续梁结构。与传统的连续梁桥比较,其具有跨越能力较大,自重比普通混凝土桥梁轻,稳定性较强,后期的运营跨中徐变挠度较小,且易于维护和检修等一系列优点。但因为薄壁箱梁本身存在翘曲变形、弯扭变形、畸变等一些因素,其结构受力分析较为复杂,因而近来年箱梁结构的分析也在不断发展。在大跨径箱梁桥应用研究方面中,有关箱梁扭转畸变效应的研究,近年愈加受到关注。在桥梁结构的应用研究中,源于箱梁薄壁化而产生的畸变效需引起重视。偏心荷载的作用下薄壁箱梁会产生:整体弯曲、刚性扭转和截面畸变三种变形。实际工程设计通常采用在箱形梁内部设置横隔板的方法来降低箱梁畸变。针对超大跨径UHPC连续薄壁箱梁桥,本文提出了密集横隔板的布置方式。鉴于此,本文作者主要进行了以下研究工作:(1)本文利用能量法的原理推导了箱梁以畸变角为变量的畸变微分方程,详细介绍了荷载分解法,探讨了以畸变角和畸变挠度两种不同变量的微分方程之间的联系互换性,比较了箱梁畸变微分方程与弹性地基梁微分方程的类似性。(2)设计制作UHPC双悬臂梁模型,对比研究不同横隔板数目的悬臂梁段在材料弹性下截面的抗扭转畸变性能。通过试验结果的对比考察密集横隔板对的畸变应力、竖向位移等的作用。试验的结果表明:薄壁箱梁整体抗扭转畸变性能强,密集横隔板数量增加能提高截面抗扭转畸变的能力,当横隔板从三块增加到四块后,扭转畸变应力下降了38%,竖向位移降幅为42%。(3)建立试验梁的有限元模型,对试验梁进行数值分析,更加细致的考察结构各方面的性能,深入分析横隔板对扭转畸变性能的影响,并与试验结果相比较,结果表明二者吻合较好。结合试验结果及有限元分析得到:UHPC密集横隔板箱梁抗扭转畸变性能强,密集横隔板数量增加能够降低扭转畸变应力和畸变角等参数。运用畸变角的大小来衡量箱梁畸变程度的指标,采用畸变角和横隔板体积来间接反映结构功能与造价之比,得出新型箱梁桥横隔板间距为3m,同时考虑密集横隔板比重(控制在总重15%以内)及施工的方便较优的横隔板间距取值范围为3~6m。
[Abstract]:The super-span unidirectional prestressed UHPC continuous thin-walled box girder bridge is made use of the excellent compressive and tensile properties of UHPC material and adopts thin-walled structure. A new type of continuous beam structure, which is composed of densely spaced box girder and a part of external prestressing, is presented in this paper. Compared with the traditional continuous beam bridge, it has a series of advantages, such as larger span capacity, lighter self-weight than ordinary concrete bridge, stronger stability, smaller mid-span creep deflection in the later stage of operation, and is easy to maintain and repair and so on. However, because the thin-walled box girder itself has some factors, such as warpage, bending and torsion, distortion and so on, the structural stress analysis of the thin-walled box girder is more complicated, so the analysis of the box girder structure has been developing in recent years. In the application of long-span box girder bridge, more and more attention has been paid to the study of torsional distortion effect of box girder in recent years. In the application research of bridge structure, the distortion effect caused by thin-walled box girder needs to be paid more attention. Under eccentric load, thin-walled box girder will produce three kinds of deformation: integral bending, rigid torsion and cross-section distortion. In practical engineering design, the box girder distortion is reduced by setting the diaphragm inside the box girder. For the super-span UHPC continuous thin-walled box girder bridge, the arrangement of dense diaphragm is proposed in this paper. In view of this, the author of this paper mainly carried on the following research work: (1) in this paper, the distortion differential equation of box girder with distortion angle as variable is derived by using the principle of energy method, and the load decomposition method is introduced in detail. In this paper, the interchangeability between differential equations with distortion angle and distortion deflection is discussed, and the similarity between box beam distortion differential equation and elastic foundation beam differential equation is compared. (2) the UHPC double cantilever beam model is designed and fabricated. The torsional distortion resistance of cantilever beams with different number of diaphragm plates under elastic material is studied. The effects of distortion stress, vertical displacement and so on the dense transverse diaphragm are investigated by comparing the experimental results. The experimental results show that the overall anti-torsional distortion performance of thin-walled box girder is strong, and the capacity of anti-torsional distortion of cross-section can be improved by increasing the number of dense diaphragm plates. When the number of diaphragm plates increases from three to four, the torsional distortion stress decreases by 38%. The vertical displacement is reduced by 42%. (3) the finite element model of the test beam is established, and the numerical analysis of the test beam is carried out, the performance of the structure is investigated in detail, and the influence of the transverse diaphragm on the torsional distortion performance is deeply analyzed. And compared with the experimental results, the results show that the two are in good agreement. Combined with the experimental results and finite element analysis, it is found that the UHPC dense diaphragm box girder has strong torsional distortion resistance, and the increase of the number of dense diaphragm plates can reduce the torsional distortion stress and distortion angle and other parameters. The distortion angle is used to measure the distortion degree of box girder, and the distortion angle and transverse partition volume are used to indirectly reflect the ratio of structural function to cost. It is concluded that the spacing between the transverse diaphragms of the new box girder bridge is 3m, and that of the new type of box girder bridge is 3m. At the same time, considering the specific gravity of the dense diaphragm (controlled within 15% of the total weight) and the convenient and better spacing range of the diaphragm for construction is 3 m / 6 m.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441

【参考文献】