高强次轻混凝土对钢管混凝土拱桥力学性能影响的研究

发布时间：2019-07-01 15:46

【摘要】：高强次轻混凝土是指在轻集料中掺入适量的普通集料配置而成的一种密度和弹性模量可变的混凝土。高强次轻混凝土既有高强普通集料混凝土强度高、刚度大、承载能力强的优点,而且也解决了易开裂和延性低的问题。钢管混凝土作为一种新型复合材料,属于钢和混凝土的组合结构,这种复合结构能够充分利用钢管和混凝土这两种材料各自的优势,所以钢管混凝土结构在轴向力作用下的承载能力远远大于两者单独受荷的承载力之和。本论文结合桥梁自身的结构和材料特性与实际承受荷载的情况,运用空间有限元分析理论来建立模型,结合高强次轻混凝土轻质、高强、优良的体积、稳定性和耐久性等特点,比较不同混凝土灌注方案,分析桥梁结构的应力、稳定性和自振等的变化特征,然后证明高强次轻混凝土对钢管混凝土拱桥力学性能的影响。本文主要开展的工作包括以下几点:(1)结合高强次轻混凝土现阶段国内外的研究现状,横向比较了它与高强普通集料混凝土和高强轻集料混凝土之间的区别,并总结了它们的工程应用情况与研究成果。论文还介绍了钢管混凝土拱桥的基本结构特点与发展现状,提出了将高强次轻混凝土用于钢管混凝土拱桥的建设中能够影响其力学性能的观点。(2)基于空间结构有限元分析法,以合江长江一桥为背景,建立大跨度钢管混凝土拱桥的空间有限元模型。并对该桥采用线弹性静力分析法,得到成桥阶段和施工阶段拱圈各位置处的应力变化。研究表明:高强次轻混凝土能够改善钢管混凝土拱桥中钢管构件和内填混凝土的受力,使他们所受的应力减小。(3)根据大跨度钢管混凝土的特点,结合拱桥稳定问题的基本理论和第一类失稳现象的特征,给出并比较了三种不同的混凝土灌注方案在成桥阶段前4阶失稳状态的稳定系数和失稳模态特征。由分析可得出结论:高强次轻混凝土能够提高大跨度钢管混凝土的稳定性。(4)本论文进行了成桥阶段的自振特性分析,得到了它们在前三阶的振型周期和名称。结果表明:采用不同灌注方案得到的自振频率相差较小,所以混凝土的密度和弹性模量的改变对结构自振频率影响不大。
[Abstract]:The high-strength secondary light concrete refers to a concrete with variable density and elastic modulus, which is formed by adding a proper amount of common aggregate into the light aggregate. The high-strength secondary light concrete has the advantages of high strength, large rigidity and strong bearing capacity, and also solves the problems of easy cracking and low ductility. The steel pipe concrete, as a novel composite material, belongs to the composite structure of steel and concrete, and the composite structure can fully utilize the advantages of the two materials of the steel pipe and the concrete, So that the bearing capacity of the steel tube concrete structure under the action of axial force is far greater than the sum of the bearing capacity of the two independent loads. Based on the structure and material characteristics of the bridge and the actual bearing load, the space finite element analysis theory is used to establish the model, and the concrete pouring scheme is compared with the characteristics of light weight, high strength, excellent volume, stability and durability of the high-strength secondary light concrete. The stress, stability and self-vibration of the bridge structure are analyzed, and the effect of the high strength secondary light concrete on the mechanical properties of the steel tube concrete arch bridge is proved. The main work of this paper is as follows: (1) The research status of high-strength and light-light concrete at present and abroad is studied, and the difference between it and high-strength ordinary aggregate concrete and high-strength light-aggregate concrete is compared, and their engineering application and research results are summarized. The basic structure and development status of the CFST arch bridge are also introduced, and the view that the high strength secondary light concrete is used in the construction of the steel pipe concrete arch bridge can influence the mechanical properties of the steel pipe concrete arch bridge. (2) Based on the finite element method of the spatial structure, the space finite element model of the long-span steel tube concrete arch bridge is set up by using the bridge of the Yangtze River as the background. And the stress change at each position of the arch ring in the bridge stage and the construction stage is obtained through the linear elastic static analysis method of the bridge. The results show that the high-strength and light-light concrete can improve the stress of the steel pipe component and the inner-filled concrete in the steel tube concrete arch bridge, so that the stress on the steel pipe concrete arch bridge can be reduced. (3) According to the characteristics of large-span steel tube concrete, combined with the basic theory of the stability problem of the arch bridge and the characteristics of the first kind of instability phenomenon, the stability coefficient and the instability mode character of the three different concrete pouring schemes in the four-order unstable state of the bridge stage are given and compared. It can be concluded from the analysis that the high-strength secondary light concrete can improve the stability of the large-span steel tube concrete. (4) The self-vibration characteristic of the bridge stage is analyzed, and the mode and name of the first three-order modes are obtained. The results show that the variation of the density and the elastic modulus of the concrete has little influence on the natural frequency of the structure.
【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U448.22;U441

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