预应力混凝土箱梁桥横向预应力框架效应的研究

发布时间：2018-08-07 13:48

【摘要】：预应力混凝土变截面箱梁桥以其良好的结构受力性能,已成为最常用的桥梁结构之一,然而在箱梁顶板中却普遍存在着纵向开裂的现象。虽然设置了横向预应力钢筋,但箱梁顶板仍然产生纵向裂缝,这表明设置的横向预应力钢筋并没有达到设计时的预期效果。张拉顶板的横向预应力筋后,引起顶板发生变形,由于箱梁是超静定结构,因此腹板必然会抵消一部分横向预应力,形成框架效应。顶板作为箱梁承受荷载的重要工作部位,研究横向预应力受腹板框架效应产生的削弱作用,对预防顶板纵向裂缝具有重要意义。本文主要针对框架效应对顶板的横向受力影响,应用ANSYS有限元分析软件以一典型变截面悬臂箱梁桥为工程背景建立实体模型,进行分析。通过模拟张拉顶板横向预应力束来研究顶板横向应力的分布规律,以及框架效应在顶板产生的影响。同时,研究了三种布置方法的横向预应力筋在腹板框架效应下受到的削弱作用,通过对比分析结果得出框架效应对顶板横向应力产生削弱作用的规律。最后,以舞阳河大桥为背景建立实桥模型进行有限元分析,研究分别在偏心预加力作用、结构自重作用以及在车辆荷载作用下顶板横向应力的分布规律。顶板横向预应力的储备应力值能否抵抗顶板的纵向裂缝产生,并对横向预应力的布置和设计提出了建议。
[Abstract]:Prestressed concrete variable section box girder bridge has become one of the most commonly used bridge structures because of its good structural mechanical properties. However, longitudinal cracking is common in the box girder roof. Although the transverse prestressed steel bar is installed, the roof of the box girder still produces longitudinal cracks, which indicates that the transverse prestressed steel bar has not achieved the expected effect in the design. Because the box girder is a statically indeterminate structure, the web must offset a part of the transverse prestressing force and form the frame effect. As an important working position of box girder subjected to load, it is of great significance to study the weakening effect of transverse prestress caused by web frame effect to prevent the longitudinal crack of roof. This paper mainly aims at the influence of frame effect on the transverse force of roof, using ANSYS finite element analysis software to build a solid model of a typical cantilever box girder bridge with variable cross section as the engineering background, and analyze it. The transverse stress distribution of roof and the influence of frame effect on roof are studied by simulating the transverse prestress of tensioned roof. At the same time, the weakening effect of the transverse prestressed tendons of three kinds of arrangement methods under the web frame effect is studied, and the law of the frame effect on the transverse stress of the roof is obtained by comparing and analyzing the results. Finally, based on the real bridge model of Wuyang River Bridge, the finite element analysis is carried out, and the distribution of roof transverse stress under the action of eccentricity preloading, structural deadweight and vehicle load is studied respectively. Whether the reserve stress value of transverse prestress of roof can resist the longitudinal crack of roof is possible, and some suggestions on the arrangement and design of transverse prestress are put forward.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441

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