钢管混凝土轴压性能试验研究与理论分析

发布时间：2018-02-02 04:04

本文关键词： 钢管混凝土力学性能膨胀剂试验研究理论分析　出处：《兰州交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：钢管混凝土以其承载力高、延性好、浇筑方便、经济效益高等优点被广泛应用于各种结构物中。目前工程界对钢管混凝土基本力学性能的研究比较多,多数研究主要集中在承载力方面。从施工的角度来看,由于温度与混凝土收缩等原因,钢管混凝土容易发生脱黏,一般通过内掺膨胀剂来补偿核心混凝土的收缩,而内掺膨胀剂又会一定程度地影响钢管混凝土的力学性能。核心混凝土徐变也会使钢管混凝土工作状态产生变化。国内对这些问题的研究还比较少。针对上述的问题,本文在前人的基础上,主要做了如下工作:(1)对钢管混凝土构件进行了轴压试验研究,主要包括轴压瞬时变形试验、轴压徐变试验和轴压承载力试验。以钢管壁厚(试件外径不变)和膨胀剂掺量(0%、4%、8%)为自变量,考察了试件轴压瞬时变形、由核心混凝土徐变引起的轴向变形和承载力随钢管壁厚以及膨胀剂掺量的变化规律。(2)借助Rapid Air型气孔结构分析仪,对不同膨胀剂掺量下的钢管核心混凝土进了气孔结构测试,通过气孔结构参数分析对比,发现膨胀剂对钢管混凝土轴压性能的影响机理主要是内掺膨胀剂提高了核心混凝土的密实度。(3)介绍了一些混凝土徐变理论和影响钢管混凝土徐变效应的常见因素。基于计算混凝土徐变的龄期调整有效模量法,推导了钢管混凝土徐变效应计算公式。通过所推导的公式,计算了钢管混凝土由核心混凝土徐变引起的轴向变形、混凝土轴向应力、钢管轴向应力随时间的变化曲线,分析了核心混凝土徐变对钢管混凝土工作状态的影响。分析、比较了不同含钢率和加载龄期对钢管混凝土徐变效应的影响。(4)介绍了钢管混凝土轴压短柱有限元模型的建立方法与基本原理,通过考虑核心混凝土损伤塑性的有限元模型,分析了钢管脱黏对构件轴压性能的影响,比较了脱黏构件和正常粘结构件的荷载—变形曲线、接触压力—变形曲线,发现脱黏减弱了构件的整体性,从而降低了轴压承载力。
[Abstract]:Concrete-filled steel tubular (CFST) has been widely used in various structures because of its high bearing capacity, good ductility, convenient pouring and high economic benefit. At present, there are many researches on the basic mechanical properties of CFST in engineering circles. Most of the research focuses on bearing capacity. From the point of view of construction, due to temperature and concrete shrinkage, concrete filled steel tube is prone to debonding. Generally, the shrinkage of core concrete is compensated by adding expansion agent. However, the mechanical properties of concrete-filled steel tube (CFST) will be affected to a certain extent by the addition of expansive agent. The creep of core concrete will also change the working state of CFST. There are few researches on these problems in China. The problem. In this paper, based on the previous work, mainly do the following work: 1) the concrete filled steel tube members of the axial compression test, including axial compression transient deformation test. Axial compression creep test and axial compression bearing capacity test. Taking the wall thickness of steel tube (without change in external diameter of the specimen) and the amount of dilatant as independent variables, the instantaneous deformation of the specimen under axial compression is investigated. Axial deformation and bearing capacity caused by creep of core concrete with the change of wall thickness of steel tube and the content of expansive agent. (2) Rapid Air type pore structure analyzer is used. The pore structure of steel tube core concrete with different amount of expansive agent was tested, and the pore structure parameters were analyzed and compared. It is found that the influence mechanism of expansion agent on axial compression performance of concrete filled steel tube is that the density of core concrete is improved by adding expansion agent. Some concrete creep theory and common factors affecting creep effect of concrete-filled steel tube (CFST) are introduced. Based on the calculation of concrete creep, the age adjusted effective modulus method is introduced. The formula for calculating creep effect of concrete filled steel tube (CFST) is derived. The axial deformation and axial stress of concrete filled steel tubular (CFST) caused by creep of core concrete are calculated. The influence of the creep of the core concrete on the working state of the concrete filled steel tube is analyzed. The influence of different steel content and loading age on creep effect of concrete-filled steel tubular (CFST) is compared. The method and basic principle of the finite element model of CFST short columns under axial compression are introduced. Through the finite element model considering the damage plasticity of core concrete, the influence of steel tube debonding on the axial compression behavior of steel tube is analyzed, and the load-deformation curves of debonding members and normal bonded members are compared. The contact pressure-deformation curve shows that debonding weakens the integrity of the member and thus reduces the axial compression capacity.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU398.9

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