新型切槽法测量混凝土梁现存应力的理论与试验研究

发布时间：2018-02-21 21:55

本文关键词： 预应力混凝土梁现存应力应力释放新型切槽法液压千斤顶　出处：《广西科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：预应力混凝土结构广泛应用于现代工程建设中,在其施工、运营过程中,因预应力施工工艺、材料收缩与徐变等因素的影响,预应力不可避免地发生损失,预应力损失的大小约为10%~20%。随着运营时间的增长,在自然环境及荷载作用的影响下,预应力混凝土结构难免会产生病害,需要维修加固。另外,一些预应力混凝土结构,随着荷载的不断增加,常常也需要结构增强。预应力混凝土结构的维修加固与增强,首先需要确定现役结构的状态,现存预应力是一个重要的指标。由于预应力混凝土结构自身应力状态的复杂性,其现存应力的测量十分困难。预应力混凝土结构现存应力的测量一直是业内研究的热点,更是难点。对于预应力混凝土结构现存应力的测量,目前使用最广泛的方法仍然是应力释放法,本文研究的新型切槽法就是在应力释放法的基础上加以改进而得到的。本文主要研究内容有:(1)在总结既有应力释放法的基础上,提出了扁型液压千斤顶技术与应力释放法相结合的新型切槽法测量技术。为了消除以往运用应力释放法测量预应力混凝土结构现存应力中混凝土弹性模量的不确定性,将扁型液压千斤顶技术与应力释放法相结合,研究了新型切槽应力释放法的测试理论,推导了有关计算公式,研制了对应的测试系统。(2)以混凝土梁模型为样本进行了实体试验研究。在梁体上切割出哑铃状槽孔,运用新型切槽法技术对该梁的现存应力值进行测量,通过实验值与理论值的对比分析,验证了新型切槽法这一技术的可行性,并对测量过程进行了详细研究。(3)应力释放测量为点测量,工程的结构为连续体结构。以测点应力描述实体的应力状态,需要合理选择测点布置,并研究非均匀介质中测点周围状态对测量结果的影响。本文采用有限元软件ANSYS建立预应力混凝土箱梁模型,通过有限元仿真模拟分析了测点的选取、槽孔尺寸、预应力筋布置等因素对新型切槽法测量可能造成的影响,目的是提高该测量方法的精度,使其成为更有效的测量方法。
[Abstract]:Prestressed concrete structure is widely used in modern engineering construction. In the process of construction and operation, due to the influence of prestress construction technology, material shrinkage and creep, prestressing force will inevitably lose. The size of the prestress loss is about 10% 20%. With the increase of operating time, under the influence of natural environment and load, the prestressed concrete structure will inevitably produce diseases and need to be repaired and strengthened. In addition, some prestressed concrete structures, With the increasing of load, it is often necessary to strengthen the structure. In order to strengthen and maintain the prestressed concrete structure, it is necessary to determine the state of the existing structure. The existing prestress is an important index. Because of the complexity of the stress state of the prestressed concrete structure, it is very difficult to measure the existing stress. The measurement of the existing stress of the prestressed concrete structure has always been a hot spot in the field of research. It is even more difficult. The most widely used method for measuring the existing stresses of prestressed concrete structures is still the stress release method. The new groove cutting method studied in this paper is improved on the basis of stress release method. The main content of this paper is: 1) on the basis of summing up the existing stress release method, In order to eliminate the uncertainty of the existing stress measurement of prestressed concrete structures, a new method of groove cutting is proposed, which combines flat hydraulic Jack technique and stress release method. Based on the combination of flat hydraulic Jack technology and stress release method, the test theory of the new groove cutting stress release method is studied, and the relevant calculation formulas are derived. The concrete beam model is used as the sample to carry out the solid test study. The dumbbell groove is cut on the beam body, and the existing stress value of the beam is measured by using the new groove cutting technique. By comparing the experimental and theoretical values, the feasibility of the new notch cutting method is verified, and the measurement process is studied in detail. The stress release measurement is a point measurement. The structure of the project is a continuum structure. In order to describe the stress state of the entity by measuring point stress, it is necessary to select the measuring point arrangement reasonably. In this paper, the finite element software ANSYS is used to establish the model of prestressed concrete box girder, and the selection of measuring point and the size of slot are analyzed by finite element simulation. The possible influence of prestressing tendons arrangement on the new method is to improve the accuracy of the method and make it a more effective measurement method.
【学位授予单位】：广西科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU378.2

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