设计及施工误差对桥梁预应力效果的影响研究

发布时间：2018-05-02 10:48

本文选题：预应力筋束 + 施工误差　；参考：《重庆交通大学》2014年硕士论文

【摘要】：预应力是预应力结构的生命线，预应力钢材的松弛对结构长期使用性能影响甚巨。目前国内外对单根预应力筋的松弛研究已经比较成熟。然而在实际结构中预应力筋往往成束使用，由于施工误差等因素造成预应力筋束内各根预应力筋锚固初应力并不均匀。预应力筋的松弛率对初应力水平非常敏感，整束预应力筋初应力非均匀分布特性对筋束松弛损失的影响尚不明确，在现有预应力结构设计规范和设计实践中也未予重视和考虑。本文针对上述问题，，基于施工现场实测数据展开数值模拟和参数分析，完成的主要工作如下： ①介绍了目前预应力张拉施工技术规范和现状，剖析了传统张拉施工技术存在的问题和预应力筋张拉质量存在的隐患（同束预应力不均匀和同断面预应力不均匀），并指出预应力筋同束不均匀对预应力松弛损失计算的影响。 ②基于施工现场预应力筋束张拉锚固时锚下有效预应力实测数据，采用随机数生成方法模拟预应力筋束锚固初应力的非均匀分布特性，利用单根预应力筋松弛损失规律对非均匀预应力筋束的松弛损失进行了研究，得出由预应力筋束内各单根力筋非均匀初应力计算的总松弛损失与由平均初应力计算的总松弛损失的比值和离散系数之间的非线性关系，并用多项式进行拟合。 ③将非均匀预应力筋束非线性松弛损失的拟合结果应用到实际的预应力混凝土连续刚构桥施工及成桥使用阶段结构仿真中，用桥梁博士进行建模计算。将表征预应力筋束不均匀度的离散系数转换为预应力筋的松弛率分别对模型进行计算和参数分析，考查不同的松弛率下各施工阶段在各控制截面的上、下边缘应力、截面开裂弯矩、以及收缩徐变下的成桥阶段主梁挠度的变化情况。 ④介绍了有效预应力检测系统以及预应力施工质量验收评估体系和检测的频率统计标准，以及针对不合格的预应力筋提出了相应的补救措施。另外，针对同束预应力筋及同断面预应力筋的不均匀度建议使用新的系统的梳编穿束的方法，并在实际的桥梁中对该措施进行了验证。
[Abstract]:Prestress is the lifeline of prestressed structure, and the relaxation of prestressed steel has a great influence on the long-term performance of the structure. At present, the research on relaxation of single prestressed tendons at home and abroad has been relatively mature. However, in practical structures, prestressed tendons are often used in bundles, and the initial stress of anchoring of prestressed tendons in prestressed tendons is not uniform due to construction errors and other factors. The relaxation rate of prestressed tendons is very sensitive to the initial stress level. The effect of the non-uniform distribution of initial stress on the relaxation loss of prestressed tendons is not clear, and has not been paid much attention to and taken into account in the existing design code and practice of prestressed structures. In order to solve the above problems, numerical simulation and parameter analysis are carried out based on the measured data of the construction site. The main work accomplished is as follows: The main contents are as follows: 1. The technical specifications and present situation of prestressed tensioning construction are introduced. This paper analyzes the problems existing in the traditional tensioning construction technology and the hidden trouble of the tensioning quality of the prestressed tendons (uneven prestress of the same bundle and uneven prestress of the same section), and points out the influence of the inhomogeneity of the prestressing tendons on the calculation of the relaxation loss of the prestressed tendons. Based on the measured data of the effective prestress under the anchor during the tensioning and anchoring of the prestressed tendons in the construction site, the random number generation method is used to simulate the non-uniform distribution of the initial stress in the anchoring of the prestressed tendons. The relaxation loss of non-uniform prestressed tendons is studied by using the relaxation loss law of single prestressed tendons. The nonlinear relationship between the ratio of the total relaxation loss calculated from the non-uniform initial stress of the prestressing tendons and the total relaxation loss calculated by the average initial stress and the discrete coefficient is obtained and fitted by polynomial. (3) the fitting results of nonlinear relaxation loss of non-uniform prestressed tendons are applied to the structural simulation of prestressed concrete continuous rigid frame bridges in construction and service stage, and the bridge doctor is used to model and calculate. The discrete coefficient which represents the unevenness of prestressing tendons is converted into the relaxation rate of prestressed tendons. The model is calculated and the parameters are analyzed respectively. The stress at the upper and lower edge of each control section in each construction stage under different relaxation rates is examined. The crack moment of the section and the deflection of the main beam under the shrinkage and creep of the bridge. 4. The effective prestress detection system, the acceptance evaluation system of prestressed construction quality and the frequency statistical standard of the inspection are introduced, and the corresponding remedial measures for the unqualified prestressed tendons are put forward. In addition, a new systematic combing method is proposed for the uneven degree of prestressing tendons and prestressed tendons in the same section, and the method is verified in practical bridges.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.57

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