中小跨径预应力混凝土梁桥的有效预应力检测方法与实验研究
发布时间：2019-06-19 05:37
【摘要】：如今中小跨径梁桥以预应力混凝土结构占据主导地位,因为预应力能提高结构的抗裂性能,是改善工作性能的重要手段,是在役预应力混凝土结构的可靠性评估的最重要的指标之一。然而,目前还没有成熟的检测在役预应力混凝土结构有效预应力的方法,较多根据规范中预应力损失理论估算得有效预应力,预应力损失各项因素间各自独立且非线性,导致了计算的复杂性。也可以结构建设期间事先埋入测试设备,该种方法虽有较高精度,但是其需要在建设期安装的特点,使其缺乏实用性且增加工程成本。因此,研究一种快速且无损的在役预应力混凝土结构有效预应力的检测方法,具有重要的工程意义。首先,列出了预应力与动刚度关系的理论模型,包括基本振动理论模型、传统分析模型、Kirchhoff动力模型、Kim Jeong-Tae理论、李瑞鸽理论,对比理论模型的原理及前人对预应力与频率间关系的试验研究,最终选定合理理论模型作为本文研究依据。同时,总结了运用实际动刚度、静刚度进行有效刚度修正的公式,为试验后续数据分析提供思路启发。另外,介绍了磁通量传感器的工作原理,为后续研究提供理论依据。按照应力等效原则,预应力混凝土T梁模型采用标准T梁缩尺比例设计而成,详细介绍了模型尺寸设计情况。然后,介绍了试验方法、测点布置、数据采集及注意事项。为保证试验测试数据的精确度,研究并对比了多种力锤激励方法,探讨影响频率测试的各种因素,提出最优方案进行试验。建立有限元模型进行模态分析,介绍了模态分析建模的注意要点及提供了实验频率理论值。实验采用静刚度(挠度)、动刚度(频率)、磁通量三种测试手段,对三片预应力混凝土T梁进行试验研究,推出静刚度与预应力之间的关系、动刚度与预应力之间的关系,尝试提出一种测试结构的静刚度或动刚度,再对在役预应力混凝土结构有效预应力进行评价的方法。另外,确定了磁通量传感器测试精度及其适用性,为有效预应力的检测方法及评价提供了一定的参考。
[Abstract]:Nowadays, prestressed concrete structure dominates the small and medium span beam bridge, because prestress can improve the crack resistance of the structure, is an important means to improve the working performance, and is one of the most important indexes to evaluate the reliability of in-service prestressed concrete structure. However, at present, there is no mature method to detect the effective prestress of prestressed concrete structures in service. According to the prestress loss theory in the code, the effective prestress is estimated. The factors of prestress loss are independent and nonlinear, which leads to the complexity of calculation. The test equipment can also be embedded in advance during the construction of the structure. Although this method has high accuracy, it needs to be installed in the construction period, so that it is lack of practicability and increases the cost of the project. Therefore, it is of great engineering significance to study a fast and nondestructive method for detecting the effective prestress of prestressed concrete structures in service. Firstly, the theoretical models of the relationship between prestress and dynamic stiffness are listed, including basic vibration theoretical model, traditional analysis model, Kirchhoff dynamic model, Kim Jeong-Tae theory, Li Rui pigeon theory, the principle of comparative theoretical model and the previous experimental research on the relationship between prestress and frequency. Finally, the reasonable theoretical model is selected as the basis of this paper. At the same time, the formulas of effective stiffness correction by using actual dynamic stiffness and static stiffness are summarized, which provides inspiration for the subsequent data analysis of the test. In addition, the working principle of magnetic flux sensor is introduced, which provides a theoretical basis for further research. According to the principle of stress equivalence, the prestressed concrete T-beam model is designed by standard T-beam scale ratio, and the size design of the model is introduced in detail. Then, the test method, the layout of measuring points, data acquisition and matters needing attention are introduced. In order to ensure the accuracy of the test data, a variety of force hammer excitation methods are studied and compared, the factors affecting the frequency test are discussed, and the optimal scheme is put forward to carry out the test. The finite element model is established for modal analysis, and the key points for attention of modal analysis modeling are introduced and the theoretical values of experimental frequency are provided. In the experiment, three test methods of static stiffness (deflection), dynamic stiffness (frequency) and magnetic flux are used to study the three prestressed concrete T-beams. The relationship between static stiffness and prestress and the relationship between dynamic stiffness and prestress are deduced. A method of testing the static stiffness or dynamic stiffness of the structure and then evaluating the effective prestress of the in-service prestressed concrete structure is proposed. In addition, the test accuracy and applicability of magnetic flux sensor are determined, which provides a certain reference for the detection method and evaluation of effective prestress.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.57
本文编号：2502133
[Abstract]:Nowadays, prestressed concrete structure dominates the small and medium span beam bridge, because prestress can improve the crack resistance of the structure, is an important means to improve the working performance, and is one of the most important indexes to evaluate the reliability of in-service prestressed concrete structure. However, at present, there is no mature method to detect the effective prestress of prestressed concrete structures in service. According to the prestress loss theory in the code, the effective prestress is estimated. The factors of prestress loss are independent and nonlinear, which leads to the complexity of calculation. The test equipment can also be embedded in advance during the construction of the structure. Although this method has high accuracy, it needs to be installed in the construction period, so that it is lack of practicability and increases the cost of the project. Therefore, it is of great engineering significance to study a fast and nondestructive method for detecting the effective prestress of prestressed concrete structures in service. Firstly, the theoretical models of the relationship between prestress and dynamic stiffness are listed, including basic vibration theoretical model, traditional analysis model, Kirchhoff dynamic model, Kim Jeong-Tae theory, Li Rui pigeon theory, the principle of comparative theoretical model and the previous experimental research on the relationship between prestress and frequency. Finally, the reasonable theoretical model is selected as the basis of this paper. At the same time, the formulas of effective stiffness correction by using actual dynamic stiffness and static stiffness are summarized, which provides inspiration for the subsequent data analysis of the test. In addition, the working principle of magnetic flux sensor is introduced, which provides a theoretical basis for further research. According to the principle of stress equivalence, the prestressed concrete T-beam model is designed by standard T-beam scale ratio, and the size design of the model is introduced in detail. Then, the test method, the layout of measuring points, data acquisition and matters needing attention are introduced. In order to ensure the accuracy of the test data, a variety of force hammer excitation methods are studied and compared, the factors affecting the frequency test are discussed, and the optimal scheme is put forward to carry out the test. The finite element model is established for modal analysis, and the key points for attention of modal analysis modeling are introduced and the theoretical values of experimental frequency are provided. In the experiment, three test methods of static stiffness (deflection), dynamic stiffness (frequency) and magnetic flux are used to study the three prestressed concrete T-beams. The relationship between static stiffness and prestress and the relationship between dynamic stiffness and prestress are deduced. A method of testing the static stiffness or dynamic stiffness of the structure and then evaluating the effective prestress of the in-service prestressed concrete structure is proposed. In addition, the test accuracy and applicability of magnetic flux sensor are determined, which provides a certain reference for the detection method and evaluation of effective prestress.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.57
【参考文献】
相关期刊论文 前1条
1 刘龄嘉,贺拴海,赵小星;在役混凝土简支梁有效预应力计算[J];交通运输工程学报;2005年03期
，本文编号：2502133
本文链接：https://www.wllwen.com/kejilunwen/jiaotonggongchenglunwen/2502133.html
