PC箱梁桥腹板开裂后的疲劳性能研究

发布时间：2018-05-22 10:40

本文选题：预应力混凝土 + 箱梁　；参考：《长沙理工大学》2015年硕士论文

【摘要】：预应力混凝土(PC)箱梁桥自上世纪初首次建造至今,国内外已经得到了广泛的使用。同时,我国经济的迅猛腾飞大力推动了交通行业的发展,车辆荷载趋于重型化,交通运输呈现出“大流量、超重和渠化交通”的特点;许多地区的在役PC箱梁桥呈现出腹板斜向开裂,轻则缩短服役年限,重则直接威胁其正常使用。为了探明PC箱梁桥腹板开裂后重复荷载作用对其性能的影响,本文做了仔细的研究分析,主要工作及成果如下:1、参阅了许多的国内外资料文献,详细介绍了PC结构及其材料组成物的疲劳性能研讨历程;介绍了传统疲劳寿命研究手段和以断裂力学为基础的疲劳裂纹扩展寿命分析方法及其求解过程。为本文的研究提供了思路及理论依据。2、本文开展了一个大型的包含有12片PC箱梁的实验室试验:其中3片梁进行静加载,3片进行两级变幅加载,6片进行等幅加载,全面分析了荷载变化情况、箍筋应变发展历程、斜裂缝的开展特征以及影响箍筋应变和裂缝开展的相关因素等对其开裂后性能的影响,仔细观察分析了试验现象和实测数据。3、通过实测数据来结合理论分析,推导出重复加载时PC箱梁箍筋的有效应变计算式,并且提出了循环加载时PC箱梁的斜裂缝宽度计算公式;可以对斜裂缝宽度进行定量计算,计算精度能够满足使用要求;对比了国内外相关规范中关于裂纹宽度计算的规定。4、建立了PC箱梁刚度退化模型及其相关联的承载力退化模型,研究了PC箱梁在重复加载过程中的刚度及承载力退化规律,为研究实际桥梁结构的剩余承载能力提供了依据;通过计算证明了基于断裂力学的裂纹扩展分析方法可以用于PC箱梁的疲劳寿命预测,但需要进一步完善研究。
[Abstract]:Prestressed concrete (PC) box girder bridge has been widely used at home and abroad since it was first built at the beginning of last century. At the same time, the rapid development of our country's economy has greatly promoted the development of the transportation industry, the vehicle load tends to be heavy, and the traffic and transportation has the characteristics of "large flow, overweight and canal traffic". In many areas, the existing PC box girder bridges show inclined cracking of webs, which shorten the service life and threaten the normal use of the bridges. In order to find out the effect of repeated load on the web of PC box girder bridge after cracking, this paper makes a careful study and analysis. The main work and results are as follows: 1. The research process of fatigue properties of PC structure and its components is introduced in detail, and the traditional means of fatigue life research and the analysis method of fatigue crack propagation life based on fracture mechanics and its solution process are introduced. This paper provides the train of thought and theoretical basis for the research of this paper. In this paper, a large laboratory experiment with 12 PC box girders is carried out: 3 beams are subjected to static loading and 3 pieces are subjected to two-stage variable amplitude loading and 6 pieces are subjected to equal amplitude loading. The influence of load variation, development history of stirrups strain, development characteristics of oblique cracks and related factors affecting stirrups strain and crack development on their post-cracking performance are analyzed. The experimental phenomena and measured data .3 are carefully observed and analyzed. The formula for calculating the effective strain of the stirrups of PC box girder under repeated loading is derived by combining the theoretical analysis with the measured data, and the formula for calculating the width of inclined cracks of PC box girder under cyclic loading is put forward. The slant crack width can be calculated quantitatively, and the calculation precision can meet the requirements of application. Compared with the domestic and foreign regulations about the calculation of crack width, the stiffness degradation model of PC box girder and its associated bearing capacity degradation model are established. The stiffness and bearing capacity degradation law of PC box girder during repeated loading is studied, which provides the basis for studying the residual bearing capacity of practical bridge structure. It is proved by calculation that the crack propagation analysis method based on fracture mechanics can be used to predict the fatigue life of PC box girder, but further research is needed.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.4

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