预应力简支小箱梁加固方法分析

发布时间：2018-11-28 17:20

【摘要】：国内外对体外预应力研究从上世纪九十年代末至今已有十多年的时间,理论和实践经验均已较为成熟。国内对体外预应力加固类似工程也做过不少;粘贴钢板加固作为被动加固,通过降低活载应力幅值,限制裂缝的发展,提高梁体抗弯承载能力,这种方法更是较为常见,但加固设计中采用体内预应力比较少见,未有作过横向比较,尤其是重载交通、超负荷下、三种加固方式各有利弊,本人参与了广州机场高速公路桥梁加固工程的全过程,该项目针对机场高速小箱梁的特征拟定了体内预应力,体外预应力,及粘贴钢板加固三种加固方式,由于加固的梁体有着基本相同的病害及施工情况,给三种加固方式的比较提供了良好的平台,通过对比探讨了每种加固方式的优缺点。从发现桥梁病害后,主要做了以下工作,1、结构病害原因分析;2、提出三种可行的加固方式并进行了理论分析;3、施工前实施荷载试验确定桥跨初始工作状态;4、加固施工;5、加固后再次进行荷载试验,通过实验验证哪种方式的加固效果最优,6、从加固效果、费用、施工难度、养护难度等多方面对三种加固方法各自的优缺点进行比对,以确定各自的适用范围,以达到归纳、推广的作用。通过试验数据的对比得出以下结论:体内预应力方案工艺较复杂,施工难度较大,尤其是增厚部分腹板顶部混凝土难以浇筑密实;体外预应力方案工艺复杂,张拉技术要求高,相对而言粘贴钢板方案工艺成熟,施工难度较低、造价较低且无需封闭交通,对于箱梁底板偏薄的工况,或大交通量的交通主干道宜优先选择该种方法。但粘贴钢板方案对胶水的质量有较高要求,胶体的长期耐久性将很大程度的影响到长期加固效果;体内预应力方案中混凝土收缩徐变会降低梁体后期预应力度;体外预应力方案则需在运营期间加强对锚头工作性能、预应力损失情况和防腐状况的检查,及时更换防腐油脂;在桥梁运营期间仍应加强交通荷载的管控,避免超载车辆的运营,同时应加强对桥梁的日常巡查工作。
[Abstract]:It has been more than ten years since the end of 1990s at home and abroad, and the theoretical and practical experience has been relatively mature. Similar projects of external prestressing reinforcement have been done in China. By reducing the amplitude of live load stress, limiting the development of cracks and improving the flexural bearing capacity of beam body, it is more common to paste steel plate as passive reinforcement, but it is rare to use internal prestressing force in reinforcement design. No horizontal comparison has been made, especially under heavy traffic and overload, each of the three reinforcement methods has its advantages and disadvantages. I have participated in the whole process of the bridge strengthening project of Guangzhou Airport Expressway. According to the characteristics of the small box girder in the airport, the project has drawn up three kinds of reinforcement methods: internal prestress, external prestress and steel plate reinforcement. Because the strengthened beam has the same disease and construction condition, It provides a good platform for the comparison of three reinforcement methods, and discusses the advantages and disadvantages of each reinforcement method. After finding the bridge diseases, the following works are mainly done: 1, structural disease cause analysis; 2, three feasible reinforcement methods are put forward and analyzed theoretically; 3, the initial working state of bridge span is determined by carrying out load test before construction; (4) strengthening construction; 5. After strengthening, the load test is carried out again, and the results are verified by experiment. 6, the advantages and disadvantages of the three reinforcement methods are compared from the aspects of reinforcement effect, cost, construction difficulty, maintenance difficulty and so on. In order to determine their respective scope of application, in order to achieve induction, promotion of the role. Through the comparison of test data, the following conclusions are drawn: the process of internal prestressing is more complex and the construction is difficult, especially the thickening part of the concrete on the top of the web is difficult to be compacted; The external prestressing process is complex, the tension technique is high, the process of sticking steel plate is mature, the construction difficulty is low, the cost is low and no closed traffic is needed, and the box girder bottom plate is thin. Or heavy traffic trunk roads should give priority to the choice of this method. The long-term durability of colloid will greatly affect the long-term reinforcement effect, and the shrinkage and creep of concrete in the prestressing plan will reduce the pre-stress degree of the later stage of the beam. The external prestressing scheme should strengthen the inspection of the working performance of the anchor head, the loss of prestress and the anticorrosive condition during the operation period, and replace the anticorrosive grease in time. During the period of bridge operation, traffic load control should be strengthened to avoid the operation of overloaded vehicles, and the daily inspection of bridges should be strengthened.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.72

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