钢—混凝土组合连续梁桥预应力施加方法研究

发布时间：2018-07-18 20:54

【摘要】：钢—混凝土组合梁桥是当前桥梁工程中的一个重要分支,它通过剪力连接件将上部混凝土桥面板与下部钢梁结合起来,可充分发挥钢材的抗拉强度和混凝土的抗压强度。对于跨度超过25m的多跨式组合梁桥,一般采用连续梁的结构形式。但是,钢—混凝土组合连续梁桥的中支点附近为负弯矩区,导致上部的混凝土桥面板受拉,下部的钢梁受压,受力较为不利。因此,需要采取一定的施工措施改善钢—混凝土组合连续梁桥负弯矩区结构的受力性能。本文简要介绍了工程中常用的钢—混凝土组合连续梁桥预应力施加方式,并对组合结构的计算理论做了相关阐述。以兰州市小西湖立交桥南滨河路高架桥一座三跨钢—混凝土组合连续梁桥为研究背景,通过Midas Civil软件建立实桥有限元模型,对本桥的施工全过程进行了计算。通过对计算结果进行分析,了解了每一设计施工步骤下,钢箱梁上下缘应力情况、桥面板应力情况及结构整体的变形情况,说明了结构在整个施工阶段应力、位移的变化规律。为了探讨不同的预应力施加方法对组合结构受力性能的影响程度,本文对背景工程的有限元模型进行了变参数分析。通过改变有限元模型中跨跨中顶力大小及顶力施加点位置、预应力钢束张拉力的大小、桥面板一次性整体浇筑与分期浇筑、考虑中支点负弯矩区钢箱梁底板填充混凝土与不考虑中支点负弯矩区钢箱梁底板填充混凝土等参数。将结构的应力、位移计算结果与设计参数下的应力、位移计算结果进行对比。得出以下主要结论;1、施加的跨中顶力对结构施工过程中的应力和位移影响程度较大,顶力施加点处钢箱梁受力较为不利。2、预应力钢束的布置可增大桥面板的压应力,改善负弯矩区混凝土桥面板的受力。3、桥面板分期浇筑可显著降低施工过程中桥面板的拉应力,但分期浇筑区段的划分应结合预应力钢束的布置确定。4、在中支点负弯矩区钢箱梁底板及墩顶填充混凝土,可显著降低钢箱梁的压应力值。
[Abstract]:The steel concrete composite beam bridge is an important branch of the current bridge engineering. It combines the upper concrete bridge deck with the lower steel beam through the shear connector, and can give full play to the tensile strength of the steel and the compressive strength of the concrete. For the multi span composite beam bridge with a span of more than 25m, the structure of continuous beam is generally adopted. However, there is a negative moment zone near the middle fulcrum of the steel concrete composite continuous beam bridge, which leads to the tension of the concrete bridge deck in the upper part and the compression of the steel beam in the lower part. Therefore, some construction measures should be taken to improve the mechanical properties of the negative bending moment zone structure of the steel concrete composite continuous beam bridge. The commonly used prestressed steel concrete composite continuous beam bridge prestressing force is applied, and the calculation theory of the composite structure is expounded. A three span steel concrete composite continuous beam bridge in the South West Lake riverside road bridge in Lanzhou city is studied, and the real bridge finite element model is set up by Midas Civil software, and the construction of the bridge is built. The whole process is calculated. Through the analysis of the calculation results, the stress situation of the upper and lower edge of the steel box girder, the stress situation of the bridge deck and the deformation of the whole structure are understood under each design construction step, and the changes of the stress and displacement of the structure during the whole construction stage are explained. In this paper, the variable parameters of the finite element model of the background engineering are analyzed. By changing the size of the top force and the position of the top force in the finite element model, the size of the tensile force of the prestressed steel beam, the one-off and staging construction of the bridge deck, and the filling of the steel box girder in the negative moment zone of the middle branch are filled in. Concrete is filled with concrete and other parameters which are not considered in the negative bending moment zone of the middle fulcrum. The calculation results of stress and displacement of the structure are compared with the stress and displacement calculation results under the design parameters. The following main conclusions are obtained. 1, the effect of the applied force on the stress and displacement in the construction process is greater, and the top force is applied. The stress of steel box girder at point is more unfavorable.2. The layout of prestressed steel beam can increase the compressive stress of the bridge deck and improve the stress.3 of the concrete bridge deck in the negative moment zone. The stage placement of the bridge panel can significantly reduce the tensile stress of the bridge deck during the construction process, but the division of the staging section should be combined with the layout of the prestressed steel beam to determine.4 and negative in the middle fulcrum. Concrete filled with steel box girder bottom and pier top in bending area can significantly reduce the compressive stress value of steel box girder.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.57

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