微膨胀钢管混凝土力学性能试验研究

发布时间：2018-05-04 05:44

本文选题：钢管混凝土 + 膨胀剂　；参考：《兰州交通大学》2014年硕士论文

【摘要】：把混凝土填充到钢管里面形成了钢管混凝土组合材料，这是利用钢管约束住核心混凝土，使内部混凝土在钢管作用下处于三向受压状态，这样提高了钢管混凝土组合材料的抗压强度和塑性变形能力。钢管混凝土有许多力学性能方面的优点，如强度高、耐疲劳、重量轻、延性好、耐冲击等优越的外，也有许多施工性能方面的优势如有省工省科、架设轻便、施工快速等，钢管混凝土结构在这些优势下，有了很快的发展。在工程实际运用中，徐变的影响对于钢管混凝土不可忽略。钢管混凝土与一般混凝土相比有很多方面优势和不同，所以其徐变更加复杂，徐变在应力增加量、拱肋挠度、混凝土应力减小量等方面对钢管混凝土构件的钢管影响都很大。从材料学设计原理上来讲，钢管混凝土是一种复合材料，而微膨胀钢管混凝土是一种新型的建筑材料，由于钢管混凝土有很多优越新能，近年来钢管膨胀混凝土在工程中得到广泛应用。混凝土的徐变一直以来是一个热点，也是一个难点，关于混凝土徐变到现在还没有一个统一的结论，而对于钢管膨胀混凝土徐变的研究更是少之又少。本文以实验为依据，介绍了国内外钢管混凝土拱桥的发展概况及钢管混凝土的力学性能；对其关键问题进行研究，主要包括钢管混凝土徐变的特点及机理；钢管混凝土徐变的主要影响因素；UEA型膨胀剂对钢管混凝土徐变、承载力、弹塑性变形及微观结构的影响，结合实验和理论分析既软件模拟得出结论：当膨胀剂掺量为8%—12%时，能提高钢管混凝土的承载力，膨胀剂的微膨胀作用能使核心混凝土更加密实，相应的钢管混凝土的承载力值越大，其对应的徐变也就越小。膨胀剂掺量的不同影响钢管混凝土纵向变形，影响规律与其对构件的承载力相反，，在一定范围内，膨胀剂掺量的增加，其纵向变形随之降低。在重复荷载作用下，当膨胀剂掺量的变化时，钢管混凝土的纵向塑性变形和弹性变形也随之变化，膨胀剂掺量与构件的塑性变形（约为40%）呈成反相关，但是和弹性变形（约为60%）呈正相关，即膨胀剂能使改善钢管混凝土的性能，起到了“增韧减脆”的作用。在全面总结本文工作的基础之上，提出了本课题仍需进一步研究的若干问题，为今后钢管混凝土拱桥的施工控制提供参考和借鉴。
[Abstract]:The concrete filled into the steel tube forms the composite material of the concrete filled with the steel tube, which uses the steel tube to restrain the core concrete and makes the internal concrete under the action of the steel tube in three directions under compression. In this way, the compressive strength and plastic deformation ability of concrete-filled steel tubular composite materials are improved. Concrete filled steel tube (CFST) has many advantages in mechanical properties, such as high strength, fatigue resistance, light weight, good ductility, shock resistance and so on. Under these advantages, concrete filled steel tube (CFST) structure has developed rapidly. In practical application, the influence of creep on concrete-filled steel tubular (CFST) can not be ignored. Compared with ordinary concrete, CFST has many advantages and differences, so its creep is more complex. Creep has a great influence on CFST steel tube in the aspects of stress increase, arch rib deflection, concrete stress reduction and so on. In terms of material design principle, concrete-filled steel tube (CFST) is a kind of composite material, and concrete-filled steel tube (CFST) is a new type of building material. In recent years, expansive concrete filled steel tube has been widely used in engineering. The creep of concrete has always been a hot spot and a difficult point. There is not a unified conclusion about the creep of concrete, and the research on the creep of expansive concrete filled steel tube is rare. Based on experiments, this paper introduces the development and mechanical properties of concrete-filled steel tubular arch bridges at home and abroad, and studies its key problems, including the characteristics and mechanism of concrete filled steel tube creep. The main influencing factors of creep of concrete-filled steel tube (CFST) are the influence of UEA type expansion agent on creep, bearing capacity, elastic-plastic deformation and microstructure of CFST. Combined with the software simulation of experiment and theoretical analysis, it is concluded that when the amount of expansive agent is between 8% and 12%, It can improve the bearing capacity of concrete-filled steel tube (CFST), and the micro-expansion effect of expansive agent can make the core concrete more dense. The larger the bearing capacity of concrete filled steel tubular, the smaller the creep of concrete filled steel tube (CFST). The longitudinal deformation of concrete-filled steel tube (CFST) is affected by the different amount of expansive agent, which is contrary to the bearing capacity of the members. In a certain range, the longitudinal deformation decreases with the increase of the content of the expansive agent. Under repeated load, the longitudinal plastic deformation and elastic deformation of concrete filled steel tube also change with the change of the amount of expansive agent, and the content of expansion agent is inversely correlated with the plastic deformation of the member (about 40%). However, there is a positive correlation with elastic deformation (about 60%), that is, the expansion agent can improve the performance of concrete filled steel tube and play the role of "toughening and reducing brittleness". On the basis of summing up the work of this paper, some problems that need further research are put forward, which can provide reference and reference for the construction control of concrete-filled steel tubular arch bridge in the future.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.38

【参考文献】