基于无扰动状态的混凝土损伤本构关系的研究

发布时间：2018-05-10 06:23

本文选题：混凝土 + 二元扰动　；参考：《沈阳建筑大学》2014年硕士论文

【摘要】：本文主要研究基于无扰动状态的混凝土弹塑性损伤本构关系,通过ANSYS软件对混凝土的力学行为进行模拟,并结合MATLAB软件对有限元模拟的结果进行绘图分析,主要工作有以下几方面：阐述了二元扰动的概念及材料改变的机理,提出了各种材料的二元扰动方程,对扰动进行了全面详细的解释。利用混凝土单轴拉伸和压缩的试验数据,绘制混凝土应力-应变曲线,并通过观察应力-应变曲线的变化规律,将其公式化,主要分为强化阶段和软化阶段,并且软化阶段存在拐点。详细分析了五参数准则,包括推导过程、偏平面和静水面的特点以及五参数准则中参数的确定。提出了混凝土弹塑性损伤本构理论,包括应力张量分解理论、混凝土本构关系以及基于塑性应变的损伤加载准则。提出了三种代表性的无扰动应力-应变曲线形式,引进扰动,通过分析塑性应变与扰动之间的关系,将其拟合成Weibull曲线,并结合有限元模拟的结果分析,得出三种无扰动应力-应变曲线均合理的结论。将无扰动应力-应变曲线公式化,利用简单的五参数准则建立有限元模型,模拟混凝土单轴受拉和单轴受压,利用提出的混凝土弹塑性损伤本构理论对模拟结果进行分析,分析数据与混凝土表观应力-应变曲线有很好的吻合性,从而验证了该理论对于一维混凝土力学行为的适用性。利用一般的五参数准则,建立混凝土T型梁模型,在有限元模型的右端面施加向下的均布荷载,使混凝土的受力状态是多向的。查看有限元模拟结果的应力应变图,得出固定端是受力构件的危险截面。通过MATLAB绘制危险截面主应力分布曲面图的方法,找出截面的危险点是上部节点和下部节点。选取有限元模型固定端截面的危险点,这些节点是多向受力的,属于一般应力状态下的节点。对于一般应力状态下节点的分析主要有：分析其应力、应变和塑性应变,利用应力张量分解理论,将应力张量分解为正负两部分,分解结果与混凝土弹塑性分析得出的受拉损伤和受压损伤一致,从而验证了混凝土弹塑性损伤本构关系同样适用于一般应力状态下的混凝土分析。利用五参数准则,通过对一维和多维的混凝土力学行为进行有限元分析,验证了本文提出的基于无扰动状态的混凝土弹塑性损伤本构关系的合理性和适用性。
[Abstract]:In this paper, the elastoplastic damage constitutive relation of concrete in undisturbed state is studied, the mechanical behavior of concrete is simulated by ANSYS software, and the result of finite element simulation is plotted and analyzed with MATLAB software. The main work is as follows: the concept of binary perturbation and the mechanism of material change are expounded, the binary perturbation equations of various materials are put forward, and the perturbation is explained in detail. Based on the experimental data of uniaxial tension and compression of concrete, the stress-strain curve of concrete is drawn, and the stress-strain curve is formulated by observing the variation law of stress-strain curve, which is divided into strengthening stage and softening stage. And there is an inflection point in the softening stage. The five-parameter criterion is analyzed in detail, including the derivation process, the characteristics of the deviation plane and the static water surface, and the determination of the parameters in the five-parameter criterion. The elastic-plastic damage constitutive theory of concrete is put forward, including stress Zhang Liang decomposition theory, concrete constitutive relation and damage loading criterion based on plastic strain. In this paper, three typical undisturbed stress-strain curves are proposed. By introducing perturbation, by analyzing the relationship between plastic strain and perturbation, the pseudo-synthetic Weibull curves are synthesized, and the results of finite element simulation are analyzed. It is concluded that all three kinds of undisturbed stress-strain curves are reasonable. The undisturbed stress-strain curve is formulated and the finite element model is established by using the simple five-parameter criterion to simulate the uniaxial tension and uniaxial compression of concrete. The simulation results are analyzed by using the proposed elastoplastic damage constitutive theory of concrete. The analytical data are in good agreement with the apparent stress-strain curve of concrete, which verifies the applicability of the theory to the mechanical behavior of one-dimensional concrete. Using the general five-parameter criterion, the concrete T-beam model is established, and the downward uniform load is applied on the right end of the finite element model, which makes the stress state of concrete multi-directional. The stress-strain diagram of the finite element simulation results shows that the fixed end is the dangerous section of the bearing member. By the method of drawing the surface diagram of the principal stress distribution of the dangerous section by MATLAB, it is found that the dangerous point of the section is the upper node and the lower node. The finite element model selected the dangerous points of the section at the fixed end. These joints are multi-directional and belong to the joints under general stress state. The analysis of the joint under general stress state mainly includes: analyzing its stress, strain and plastic strain, using the theory of stress Zhang Liang decomposition, decomposing the stress Zhang Liang into two parts: positive and negative. The decomposition results are consistent with the tensile damage and compressive damage obtained from the elastic-plastic analysis of concrete, which verifies that the constitutive relationship of elastoplastic damage of concrete is also applicable to the analysis of concrete under general stress state. By using the five-parameter criterion, the finite element analysis of one-dimensional and multi-dimensional concrete mechanical behavior is carried out, which verifies the rationality and applicability of the elastoplastic damage constitutive relationship of concrete based on the non-perturbed state proposed in this paper.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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