【作者】 黄立浦；

【导师】 杨美良；

【作者基本信息】 长沙理工大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 近年来,国内外桥梁工作者对体外预应力结构,做了大量的试验和理论分析工作,探讨体外预应力结构的受弯性能和体外索应力增量的分析,但取得的研究成果差异较大,因此需要进一步进行探讨。同时由于预制节段施工方法具有整体施工方法不可比拟的优点,预制节段施工体外预应力桥梁得到工程界的普遍认可,并在实际工程中得到越来越广泛的应用。因此本文针对预制节段拼装的体外预应力桥梁进行了研究。(1)对节段施工体外预应力桥梁结构,在转向装置处会由于摩擦作用而产生体外索的应力重分配。本文根据摩擦引起预应力损失、无应力索长不变和变形协调原理,对索应力重分配进行计算,提出了体外索索力计算的方法。分析了极限状态下体外索的增量与结构整体变形之间的关系。(2)在预制节段施工体外预应力桥梁中,一方面体外索的变形、索力的变化不再与主梁截面应变相协调,而是与结构的整体变形相关;另一方面节段间接缝在法向方向只能承受压应力,一旦受拉即退出工作。两方面使得预制节段施工体外预应力桥梁的结构分析变得较为复杂。本文对已有的混凝土有限元模型(分离式模型、组合式模型、整体式模型)进行综述比较,选用了其中适用面广、计算精度高的分离式模型。建立了能够模拟节段施工体外预应力混凝土梁的接缝力学性能的单元模型。(3)建立了一个能够对钢筋混凝土结构和体外预应力混凝土结构的抗弯性能进行全过程分析的有限元模型,该模型综合考虑了材料的物理非线性、结构的几何非线性以及接缝单元的正确选择及索应力在摩擦作用下的重分配计算。(4)在模型基础上开发了非线性有限元程序,程序可以进行普通钢筋混凝土、体外有粘结、体外无粘结、以及体内配置普通钢筋的体外预应力梁桥成桥后加载的全过程分析;能够对体外索与转向块之间由于摩擦作用产生的对节段施工体外预应力桥梁结构的影响做出准确的分析与计算。运用试验结果与程序计算结果的数据对比对本文建立的有限元模型和编写的程序进行了验证。(5)择一节段施工的体外预应力桥梁为研究对象,利用自编程序就摩擦系数的取值对体外索在转向块处的滑移、体外索在转向块处两边的索力差值、结构的线性响应荷载和节段施工接缝开裂荷载的影响进行了研究。结合参考文献资料的试验结果和本文的分析研究,对体外预应力桥梁的设计提出了建议。更多还原

【Abstract】 In recent years, bridge workers at home and abroad have done a lot of experiments and theoretical analysis on external pressing structure, and explored the flexural behavior and stress increment of the bending properties, but there is large difference among research results. And therefore it needs to be further explored. At the same time, as the construction of precast segmental building method has unparalleled advantages compared with integral construction method, the construction of precast segments in vitro prestressed bridge has generally recognized by the engineering sector, and been widely used in practical engineering. As a result, this paper studies on precast segments assembled in vitro prestressed bridge.(1) About the construction on the section of the stress increment on the external pressing bridge, the vitro cable stress produced in the steering due to friction arising from the role of stress will be re-allocated. This paper recalculated the re-allocation of the vitro cable stress, based on the pre-stressed loss caused by friction, no claim of stress and deformation of the same principle, and then puts forward the calculating method of vitro tension. It analyzed the relationship between the increment under limit state and the deformation of the overall structure.(2)In the construction of precast segments in vitro prestressed bridge, on one hand, the deformation in vitro cable and the cable force will not change with the main beam cross-section which should be coordinated in disguise but related to the overall structure and deformation; on the other hand, the segments in the indirect method to the seam direction can only withstand stress, once it is subjected to tension, it will be out of work. Both made vitro analysis of precast segments of prestressed bridge become more complex. This essay has given an overall review on the concrete finite element model (separate model, the modular model, the overall model), the choice model which apply a wide range and high accuracy of the separation model to simulate a section of the vitro construction of prestressed concrete beam joints mechanical properties of the element model.(3)A finite element model has been established, which can analyze the flexural resistance of a reinforced concrete structure and vitro prestressed concrete structure in the whole process of bending performance. The models considered the physics of non-linear, non-linear of geometric structure, the correct choice of the joint unit of cable and stress the role of friction in the re-allocation of calculation. (4) The model has been developed on the basis of non-linear finite element program. The programs can be used to analyze the whole procedure of ordinary reinforced concrete, bonded in vitro without bond, and the allocation of ordinary steel in the vitro prestress into a bridge after loading. It is able to make accurate analysis and calculation on the effect of external pre-stressing segmental construction between the role of vitro construction and the section of the bridge structure because of the friction. It verifies the finite element model and the preparation of the procedures presented in this paper by comparing the test results and procedures for calculating.(5)The writer takes the construction of a prestressed bridge as the study object, using self procedures on the value to study the impact of the coefficient of friction in the in vitro cable to block the slip, in vitro cable to block the cable force on both sides of the margin and the structure Linear response to load and segmental construction joints cracking load. Combining the reference information on the testing results and the analysis of this research,this thesis put forward suggestions on vitro prestressed bridge design.更多还原