圆钢管混凝土柱施工期结构性能研究

发布时间：2018-11-08 19:27

【摘要】：近年来，高层和超高层建筑结构在我国发展迅速，各地的建筑高度不断被刷新。伴随着高层超高层建筑的不断发展，钢-混凝土组合结构这一特殊的结构形式也得到了广泛的应用，因为它能满足人们对建筑空间宽敞性和灵活性的要求。作为一种新型的结构形式，钢-混凝土组合结构能够充分发挥钢材和混凝土的材料优点，应用前景良好。作为钢-混凝土组合结构的一种，钢管混凝土因具有承载能力高、塑性和韧性好、施工简便以及良好的经济效益等优点而越来越被工程界所青睐，于近些年得到了快速的发展，已经大量应用于高层、大跨以及空间等结构。得益于钢管可以直接充当模板，钢管混凝土很好地解决了混凝土浇筑和施工速度之间的矛盾。由于在施工时，一般是先固定好钢管，然后再浇筑混凝土，这就造成了钢管内部会产生初应力以及混凝土在早龄期的受力问题，这会在一定程度上对构件施工期的结构性能产生一定的影响。本文对钢管混凝土柱在施工期的结构性能进行了研究，主要完成了以下工作： ①分析了混凝土强度、弹性模量和泊松比随龄期的发展关系。混凝土强度和弹性模量发展趋势类似，在早期发展比较快，强度在7天时能够达到标准强度的70%左右，但后期增长较慢，趋于稳定；而泊松比在在各龄期时发展变化不大，整体在0.18左右。 ②系统地研究了施工期受力对钢管混凝土后期性能的影响，通过控制钢管初应力大小不大于其抗压强度的60%以及混凝土早龄期受力大小不大于其当时强度的70%，并保证混凝土后期的养护条件符合规范要求，，来保证钢管混凝土后期强度的发展。 ③钢管和混凝土的相互作用，使得钢管混凝土的徐变变得复杂。本文采用多轴理论对钢管混凝土在轴压荷载作用下的徐变进行分析，得出以下结论：应力级别增加会导致徐变增加；含钢率的增大会增强钢管对混凝土的约束效应，从而导致徐变减小；混凝土的徐变会随其强度的增长而变大。 ④利用有限元软件ABAQUS对处于施工期阶段的钢管混凝土柱在轴压和偏压荷载作用下的受力性能进行模拟分析。得出在钢管混凝土的强度在早期增长幅度较快，后期增幅变小；在小偏心荷载作用下，由于构件受力不均匀，需要将钢管对核心混凝土的约束作用进行折减。构件在破坏时表现为强度破坏，破坏截面全部发展为塑性。 ⑤针对钢管混凝土这一特殊的结构形式，从结构设计、材料选择以及施工三个方面提出措施来保证钢管混凝土在施工期的安全和质量。
[Abstract]:In recent years, high-rise and super-high-rise building structures have developed rapidly in our country. With the continuous development of high-rise and super-high-rise buildings, the steel-concrete composite structure has been widely used, because it can meet the requirements of the spacious and flexible building space. As a new type of structure, steel-concrete composite structure can give full play to the advantages of steel and concrete materials, and has a good application prospect. As a kind of steel-concrete composite structure, concrete-filled steel tube (CFST) is more and more popular in engineering field because of its advantages of high bearing capacity, good plasticity and toughness, simple construction and good economic benefit, and has been developed rapidly in recent years. It has been widely used in high-rise, long-span and space structures. Because the steel tube can be used as a formwork directly, the contradiction between concrete pouring and construction speed is well solved. In construction, the steel pipe is usually fixed first, then the concrete is poured, which causes the initial stress inside the steel tube and the stress of the concrete at the early age. To a certain extent, this will affect the structural performance of components during construction. In this paper, the structural properties of concrete-filled steel tubular columns during construction are studied. The main works are as follows: 1 the relationship between the strength, elastic modulus and Poisson's ratio of concrete with age is analyzed. The development trend of the strength and elastic modulus of concrete is similar. The strength can reach about 70% of the standard strength at 7 days, but the growth is slow and tends to be stable in the later stage. The Poisson's ratio changed little at each age, and the whole was about 0.18. (2) the effect of stress on the later performance of concrete filled steel tube during construction period is systematically studied. By controlling the initial stress of steel tube not more than 60% of its compressive strength and the force of concrete at early age not greater than 70% of its strength at that time, The later curing conditions of concrete are in accordance with the specifications to ensure the development of later strength of concrete-filled steel tubular (CFST). The interaction between steel tube and concrete makes the creep of concrete filled steel tube become complicated. In this paper, the multi-axial theory is used to analyze the creep of concrete-filled steel tube under axial compression. The following conclusions are drawn: the increase of stress level will lead to the increase of creep; The increase of steel-containing ratio will enhance the restraint effect of steel pipe on concrete, which will lead to the decrease of creep, and the creep of concrete will increase with the increase of its strength. (4) the finite element software ABAQUS is used to simulate and analyze the behavior of concrete-filled steel tubular columns under axial and eccentric loads during the construction period. It is concluded that the strength of concrete-filled steel tube (CFST) increases rapidly in the early stage and becomes smaller in the later stage. Under the action of small eccentricity, it is necessary to reduce the constraining effect of the steel tube on the core concrete due to the non-uniform force of the members. The failure behavior of the member is strength failure, and the failure section develops into plasticity. 5. Aiming at the special structure form of concrete-filled steel tubular (CFST), this paper puts forward some measures to ensure the safety and quality of CFST during construction from three aspects: structural design, material selection and construction.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU398.9

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