【作者】 杨万里；

【导师】 项贻强；

【作者基本信息】 浙江大学 ， 桥梁与隧道工程， 2008， 博士

【摘要】 目前简支连续预应力混凝土多箱式桥梁的应用日趋广泛,随着科技的进步及吊装能力的提高,跨径范围的增大以及在中小跨径领域内设计标准化的趋势十分明显。但目前国内外对先简支后连续多箱式桥梁的试验和全过程的理论分析研究相对滞后,严重阻碍了该结构体系的健康发展。本文根据2005浙江省交通厅科技计划项目《预应力混凝土多箱式桥梁受力性能的分析及试验研究》下达的课题,进行了详细的试验研究和理论分析。主要结论:1)针对简支连续预应力混凝土箱梁桥,利用有机玻璃制作模型进行试验研究,验证实体退化的虚拟层合单元分析理论和程序的正确性和合理性。2)研究讨论以虚拟层合单元计算预应力空间效应的方法,并以一座典型的5跨连续多箱式箱梁桥为背景,对其从施工到成桥阶段进行全程的受力分析。详细分析不同阶段下,单体小箱梁的空间受力特性和多个小箱梁横向连接后的整体力学性能的变化,结果表明多箱式箱梁桥结构的边梁在单体状态下由于结构的扭转体现出明显的空间效应、但是结构的纵向连续和横向联接对这种效应有一定的抑制;除自由扭转外,小箱梁内部的剪力滞后等空间效应并不明显。3)针对简支变连续结构体系的后连续端部的浇筑顺序、后连续预应力的张拉顺序及临时支座拆除顺序等施工工艺存在的分歧,利用所提出的虚拟层合单元建模分析研究了各片小箱梁关键点的应力、挠度随不同施工工序的变化规律,提出了合理的最优施工工序。4)在已有三维实体退化虚拟层合单元的基础上,通过引入ottenson四参数破坏准则的非均匀强化弹塑性本构关系模型,扩展了程序的材料库。同时结合虚拟层合单元的建模特点,研究发展了单元中的生死块技术,进一步扩展了程序的功能及使用范围。以某高速公路上一座标准设计的5跨连续小箱梁桥为背景,对其进行了多工况的极限承载力分析,考察不同的桥梁连续跨数带来的结构极限承载能力的变化,探讨了随着荷载的逐渐增大,小箱梁桥的结构受力性能、荷载在各梁间分配比例的变化规律,研究了预应力混凝土箱梁桥结构在计入塑性后的内力重分布的规律,并考察了跨中横隔梁对结构非线性受力性能的影响。此外分析研究了板厚、预应力度、预应力筋和普通钢筋配筋率等设计参数对小箱梁桥承载能力的影响。根据分析获得的破坏荷载、破坏特征、荷载位移曲线以及桥梁安全系数等,为小箱梁桥的进一步优化设计提供理论依据。更多还原

【Abstract】 Simply supported continuous P.C. multi-box bridges are widely used nowadays. With the development of science and the improvement of the suspend capacity, there has been a noticeable trend in the enlargement of span range and the standardization of medium and small-span bridge design. But the test researches and the whole loading process analysis on the simply supported continuous P.C. multi-box bridges both inland and overseas are relatively laggard, which has stunted the healthy development of this type of bridge badly. According to the item of "Analysis and Experimental Study on the Mechanical Behavior of P.C. Multi-box Girder Bridge" which is a science and technology project item of Ministry of Communications, Zhejiang Province, detailed test analysis and theoretic research are done. And the primary achievements are listed as follows.1) Polymethyl methacrylate structural model test is done, focusing on simply supported continuous P.C. multi-box bridges, and the applicability and the exactitude of the solid degenerated virtual laminated element theory and program are verified.2) The Pre-stress spatial effect calculation method based on virtual laminated element is researched. Then a 5 X 25m multi-box girder bridge in the highways is adopted as the engineering antitype, and its mechanical behavior is analyzed for the whole process from the construction stage to the finish state. The spatial effect of a single box and the workability changes because of transverse connections are discussed in detail. The results show that the side girder put up apparent spatial stress distribution because of free torsion, and the transverse and the lognitudinal link of the girders can reduce the effects to some degree. No spatial effect such as shear lag effect exists except for free torsion.3) To the simply supported-continuous construction techniques bifurcation about the sequences of post-connection concrete cast, the pre-stress wires tension and the temporary support removal, the stress and displacement of the key points in different construction sequences are fetched with the FE model constructed with virtual laminated element, then a most rational construction sequence is put up.4) Based on present 3-demension solid degenerated virtual laminated element program, the non-uniform hardening plastic relationship of Ottenson 4-parameter failure criterion is deducted and the material muster of the program is enlarged; the live-dead blocks technique is developed for pre-stress wires based on the construction characteristics of the USAP model, which expands its applicable extension. A standard designed 5 X 25m multi-box girder bridge in the highways is adopted as the engineering antitype, the ultimate loading capacity in various loading cases are calculated. The safety of the structure with different numbers of spans is investigated; the mechanical behavior changes and the load transverse distribution coefficient changes in increasing loadings are discussed; the force re-distribute disciplinarian when the structure is in plastic stage and the influence of middle diaphragm are discussed. Besides, the influence of some design parameters such as pre-stress degree, pre-stress amounts, hoop steel areas, bottom plate steels area, upper plate depth, bottom plate depth and web depth on the ultimate loading capacity of the bridge is analyzed. Some useful conclusions are made based on the ultimate loading, failure characteristics, displacement-load diagrams and safety coefficients calculated, etc, which also provide the theoretical foundation for the optimization of the structure design.更多还原