预应力混凝土连续梁桥病害分析及体外预应力加固研究

发布时间：2018-05-31 11:40

本文选题：下挠 + 徐变　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：在最近二三十年来，，PC连续梁桥由于其跨越能力强、受力性能好以及外观优美等优点在我国发展迅速，但是其普遍存在下挠过大以及开裂等病害。本文从设计角度分析出现这些病害的原因，具体从混凝土徐变效应和箱梁剪力滞效应的角度进行分析，为设计提供一定参考。通过对箱梁的受力特性以及PC梁桥下挠的成因进行了深入的讨论，得出对于徐变效应的计算分析不准确是目前大跨PC梁桥下挠过大的主要原因之一，深入研究了目前常用桥梁设计软件计算徐变效应的方法及其存在的缺陷，提出并实现了基于ANSYS采用三维实体单元并计入预应力筋松弛过程影响的计算PC梁桥徐变效应方法，并对三股线高架桥的徐变效应进行了分析，得出了对设计有一定参考价值的结论。对PC箱梁桥常见裂缝及成因进行了讨论与分析，分析了剪力滞效应对箱梁桥的影响，并认为剪力滞效应对箱梁桥的裂缝有重要影响，详细分析了三股线高架桥的剪力滞效应，并研究了宽跨比、顶板厚度、上翼板悬臂长度、腹板倾斜情况对剪力滞效应的影响，结果表明，宽跨比以及上翼板悬臂长度对剪力滞效应的影响较为显著。从减小剪力滞效应的角度出发，提出了有一定价值的设计建议。对于目前常用的桥梁加固方法进行了研究和探讨，分析了体外预应力加固法的一些关键技术问题。对三股线高架桥进行体外预应力加固，结果表明，该方法能有效的纠正挠度，加固效果明显。
[Abstract]:In recent twenty or thirty years, continuous beam bridge with PC has developed rapidly in our country because of its strong span ability, good mechanical performance and beautiful appearance, but there are many diseases such as overdeflection and cracking. In this paper, the causes of these diseases are analyzed from the point of view of design, and the concrete creep effect and the shear lag effect of box girder are analyzed in detail, which provides a certain reference for the design. Based on the deep discussion of the stress characteristics of box girder and the cause of the underdeflection of PC girder bridge, it is concluded that the inaccurate calculation and analysis of creep effect is one of the main reasons for the excessive underdeflection of PC girder bridge with long span at present. In this paper, the method of calculating creep effect of bridge design software is studied in detail, and the method of calculating creep effect of PC beam bridge based on ANSYS is proposed and realized, which takes into account the relaxation process of prestressed tendons. The creep effect of three strands viaduct is analyzed. The common cracks and their causes of PC box girder bridge are discussed and analyzed. The influence of shear lag effect on box girder bridge is analyzed. It is considered that shear lag effect has an important effect on the crack of box girder bridge, and the shear lag effect of three strands viaduct is analyzed in detail. The effects of the ratio of width to span, the thickness of roof, the length of the cantilever of the upper wing and the inclination of the web on the shear lag effect are studied. The results show that the ratio of width to span and the length of the cantilever of the upper wing have a significant effect on the shear lag effect. From the point of view of reducing shear lag effect, some valuable design suggestions are put forward. In this paper, the commonly used bridge reinforcement methods are studied and discussed, and some key technical problems of external prestressing reinforcement method are analyzed. Three strands viaduct is strengthened by external prestressing. The results show that the method can correct deflection effectively and the effect of reinforcement is obvious.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.7

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