变截面钢—混凝土组合连续梁桥受力特性分析

发布时间：2018-01-13 01:20

本文关键词：变截面钢—混凝土组合连续梁桥受力特性分析　出处：《兰州交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：近年来，钢-混凝土组合结构在工程中得到广泛应用，但人们对组合结构的一些问题的研究还不够深入，比如收缩徐变问题。收缩徐变使组合结构产生内力及应力重分布，影响结构的承载能力；对于钢-混凝土组合连续梁桥，支座区域较大的负弯矩容易使桥面板拉应力过大产生开裂的现象等。本文以赞比亚奇阿瓦40m+60m+40m钢-混凝土组合连续梁桥为工程背景，借助Midas/Civil有限元分析程序对该桥进行分析，针对徐变对组合梁产生的内力及应力重分布，温度作用效应，负弯矩下混凝土桥面板裂缝宽度，以及减小负弯矩区段桥面板拉应力的施工方法这几个方面进行分析。具体工作如下： 1、分析桥面板混凝土徐变对组合梁的内力及应力重分布作用，分析了加载龄期和相对湿度对徐变效应的影响，混凝土收缩对徐变效应的影响。温度作用对组合梁桥内力的影响，得出温度应力主要由混凝土和钢梁之间的温差产生。同时分析了温差作用下，当桥面板厚度及弹性模量比变化时，组合梁应力变化规律。 2、对负弯矩作用下桥面板的承载力及裂缝宽度进行了计算，结果表明均满足规范要求。计算了不同荷载工况下桥面板裂缝宽度，得出影响负弯矩下桥面板裂缝宽度的最不利荷载。分析了相对湿度，，组合梁的截面高度比以及桥面板的配筋率三种因素对桥面板裂缝宽度的影响。 3、针对连续组合梁桥负弯矩区桥面板承受较大拉应力的问题，对比分析了桥面板分区段浇筑和一次性浇筑两种施工方法对成桥后组合梁应力的影响，结果表明采用分区段浇筑混凝土桥面板能够有效降低负弯矩区混凝土桥面板拉应力，提高了桥面板的抗裂性能。 4、研究支点位移法在连续组合梁桥施工中的应用，对比分析了采用和未采用支点位移法成桥时组合梁应力，结果表明采用支点位移能使负弯矩区桥面板混凝土形成一定的压应力储备。增加支点升降量使桥面板预压应力增大同时改善支座处钢梁下缘的受压，但同时徐变的卸载作用也呈线性增长。对比分析了同时顶升中支点和按照先后顺序顶升中支点两种方案，结果表明后者对负弯矩区的预压效果更为明显。
[Abstract]:In recent years, steel-concrete composite structures have been widely used in engineering, but the research on some problems of composite structures is not deep enough. For example, the shrinkage and creep causes the internal force and stress redistribution of the composite structure, which affects the bearing capacity of the structure. For steel-concrete composite continuous beam bridges. The large negative bending moment in the bearing region easily leads to the cracking of the slab tensile stress, etc. In this paper, the construction background of the steel concrete composite continuous beam bridge in Chiawa, Zambia, is 40 m 60 m 40 m. The Midas/Civil finite element analysis program is used to analyze the bridge. Aiming at the internal force and stress redistribution of the composite beam caused by creep, the effect of temperature, the crack width of concrete deck slab under negative bending moment is analyzed. And the construction methods of reducing the tensile stress of the bridge deck in the negative bending moment section are analyzed. The specific work is as follows: 1. The internal force and stress redistribution of concrete creep on composite beam are analyzed, and the influence of loading age and relative humidity on creep effect is analyzed. The effect of concrete shrinkage on creep and the effect of temperature on internal force of composite beam bridge. It is concluded that the temperature stress is mainly caused by the temperature difference between concrete and steel beam. At the same time, the effect of temperature difference is analyzed. When the slab thickness and elastic modulus ratio change, the stress of composite beam changes. 2. The bearing capacity and crack width of bridge deck under negative bending moment are calculated, and the results show that they all meet the requirements of the code, and the crack width of deck slab under different load conditions is calculated. The influence of relative humidity, section height ratio of composite beam and reinforcement ratio of deck slab on the crack width of bridge deck slab is analyzed, and the most unfavorable load affecting the crack width of deck slab under negative bending moment is obtained, and the effect of relative humidity, section height ratio of composite beam and reinforcement ratio of deck slab on the crack width of deck slab is analyzed. 3. Aiming at the problem that the deck slab of continuous composite girder bridge bears large tensile stress in negative bending moment region, the influence of two construction methods on the stress of composite beam after completion of the bridge is compared and analyzed. The results show that the tensile stress of concrete deck slab in negative bending moment region can be reduced effectively, and the crack resistance of concrete deck slab can be improved. 4. The application of fulcrum displacement method in the construction of continuous composite beam bridge is studied, and the stress of composite beam when the bridge is constructed with or without fulcrum displacement method is compared and analyzed. The results show that using fulcrum displacement can make concrete of bridge deck in negative moment region form a certain amount of compressive stress reserve, increase fulcrum lift increase the pre-compression stress of deck slab and improve the compression of the lower edge of steel beam at the support. But at the same time, the unloading effect of creep increases linearly. The results show that the preloading effect of the latter is more obvious in the negative moment region.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.215

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