大跨度连续箱梁桥底板纵向裂缝成因机理及防治措施

发布时间：2018-11-06 09:33

【摘要】：连续梁桥由于其结构简单、施工方便等特点,较为广泛的运用在很多桥梁工程中,在我国已建成的大跨径连续梁桥已具有一定规模。近些年来,由于设计及施工各方面原因,连续梁底板出现的纵向裂缝因其具有很大的危害性而引起了人们的关注。为研究连续梁底板纵向裂缝的成因机理及其防治措施,本文做了如下工作:(1)针对连续梁桥底板纵向裂缝的研究现状,结合国内外专家学者的相关研究;从箱形截面梁的受力特征出发,分析发现底板的横桥向拉应力是连续梁底板纵向裂缝开展的主要原因,并阐述了研究连续梁底板纵向裂缝对工程安全、国民经济的实际意义。(2)在考虑到底板预应力作用、环境温度作用以及外加荷载作用下,计算推导出底板横向应力的简化计算公式。(3)结合实际的工程背景,分析计算在不同的连续梁参数下底板横向应力的变化。采用有限元法进一步验证,并结合部分试验数据,发现混凝土的自重及环境梯度以及箱形截面的高度等因素的变化,对底板的横桥向应力几乎没有影响;而箱梁桥底板线形抛物线方程的系数与指数的增加、箱形截面底板厚度的减小、底板宽度的增加、合拢段高差及力筋的定位误差都会在一定程度上增大底板的横向拉应力,对横向拉应力影响较大。同时发现,在靠近跨中段的截面上,这些参数的变化对底板的横向应力影响更为突出。(4)采用有限元方法计算发现,在收缩徐变的作用下,连续梁底板混凝土的横向拉应力在成桥后很长一段时间内不会显著减小。为避免底板的纵向裂缝的开展,成桥后还需注意桥梁的保养以及规范使用。(5)以研究成果为基础,针对连续梁桥底板纵向裂缝的防治方法,分别从设计及施工两个角度进行探讨,提出了相应的控制措施以及注意事项。
[Abstract]:Continuous beam bridge is widely used in many bridge projects because of its simple structure and convenient construction. The long-span continuous beam bridge has been built in our country and has a certain scale. In recent years, due to various reasons of design and construction, the longitudinal cracks on the bottom slab of continuous beam have attracted people's attention because of its great harm. In order to study the formation mechanism and prevention measures of longitudinal cracks in continuous beam floor, this paper has done the following work: (1) according to the current research situation of longitudinal cracks in the bottom slab of continuous beam bridge, combined with the relevant research of experts and scholars at home and abroad; Based on the stress characteristics of box section beam, it is found that the transverse bridge tensile stress of bottom slab is the main reason for the longitudinal crack development of continuous beam bottom slab, and it is safe for engineering to study longitudinal crack of continuous beam bottom slab. The practical significance of the national economy. (2) under the consideration of the prestressing action of the floor slab, the effect of ambient temperature and the effect of external load, the simplified formula for calculating the transverse stress of the bottom slab is derived. (3) considering the actual engineering background, The change of transverse stress of bottom plate under different parameters of continuous beam is analyzed and calculated. The finite element method is used to further verify, and combined with some experimental data, it is found that the variation of concrete deadweight, environmental gradient and height of box section has little effect on the transverse bridge stress of the bottom slab. However, the increase of coefficient and index of the linear parabola equation of the bottom plate of box girder bridge, the decrease of the thickness of the bottom plate of the box section, the increase of the width of the bottom plate, the height difference of the closing section and the positioning error of the force bars will increase the transverse tensile stress of the bottom plate to a certain extent. It has great influence on transverse tensile stress. At the same time, it is found that in the section near the middle of span, the influence of these parameters on the transverse stress of the bottom plate is more prominent. (4) by using the finite element method, it is found that under the action of shrinkage and creep, The transverse tensile stress of continuous beam slab concrete will not decrease significantly after the bridge is completed for a long time. In order to avoid the development of longitudinal cracks in the bottom slab, it is necessary to pay attention to the maintenance and standard use of the bridge after the completion of the bridge. (5) based on the research results, aiming at the prevention and cure method of the longitudinal crack in the bottom slab of the continuous beam bridge, The corresponding control measures and points for attention are put forward from the two angles of design and construction.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.213;U445.57

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