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五种本构模型在钢管混凝土有限元中的比较 总被引:3,自引:0,他引:3
采用Von Mises、Mohr Coulomb和Drucker Prager三种经典模型、以及两种适用于混凝土材料的Smeared Cracking模型和Damaged Plasticity模型,分别对带约束拉杆和无约束拉杆的方形、矩形钢管混凝土短柱轴压承载力进行有限元分析,简述每种本构模型的特点,并与已有的47个钢管混凝土短柱轴压试验结果对比。结果表明与静水压力无关且忽略混凝土塑性体积膨胀的VonMises模型无法考虑钢管对混凝土的约束作用以及约束拉杆的作用,采用相关流动法则而低估了塑性体积膨胀的Smeared Cracking模型分析结果略低于试验结果,其他三种考虑静水压力并采用不相关流动法则的模型更符合试验结果,而且三者计算结果很接近。 相似文献
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钢管混凝土结构是由混凝土填人钢管内而形成的一种新型组合结构。本文对钢管混凝土施工工艺如何运用到建筑工程中进行了介绍。 相似文献
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钢管混凝土结构非线性有限元分析中混凝土边界面模型的研究及应用 总被引:2,自引:0,他引:2
本文在理论分析和试验结果的基础上,针对钢管混凝土结构受力特点,对混凝土边界面模型进行了研究,它不仅较全面地反映了材料在三向复杂应力状态下的性能,准确可靠,而且在非线性有限元计算中简单可行。 相似文献
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钢管混凝土结构材料非线性的一种有限元分析方法 总被引:2,自引:1,他引:2
为了更简单地考虑梁单元的材料非线性受力性能,把断面广义力和广义应变的概念运用于单元分析中,将单元的弹塑性刚度矩阵分离为弹性刚度矩阵和塑性刚度矩阵。这样,梁单元的变形可以由弹性变形和塑性变形简单地迭加,结构内力可通过弹性应变能的斜率(弹性刚度矩阵)与位移的乘积求得,从而在增量-迭代计算时可较准确且较快地计算出结构变形后的不平衡力。应用这一计算方法,推导了基于纤维模型的三维梁单元的钢管混凝土结构的有限元基本公式,并将其植入能考虑几何非线性的三维梁单元非线性计算程序NL_Beam3D中以计算结构的双重非线性问题。算例分析表明该方法和程序能较准确地反映钢管混凝土结构的双重非线性特性。 相似文献
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钢管混凝土肋拱面内受力全过程有限元分析 总被引:9,自引:0,他引:9
本文编制了考虑几何与材料双重非线性的钢管混凝土肋拱面内受力的有限元程序。材料非线性应用合成法钢管混凝土本构关系。计算结果与试验结构比较表明,该程序能够反映钢管混凝土肋拱受力全过程的基本特性,但在受力的后期有一定的误差,表明钢管混凝土肋拱中的材料本构关系有其自身的特点。 相似文献
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该文基于统一强度理论建立高强钢管混凝土柱的屈服准则。考虑到柱的水平侧移在截面上引起的附加弯矩作用,假设截面应力在屈服前呈线性分布。引入临界斜率k′的定义,以此斜率作为全截面受压的临界值。由平衡条件得到钢管混凝土柱内不同点处的应力状态,代入统一强度理论(UST)得到高强钢管混凝土柱的屈服函数,并采用相关联流动法则建立塑性势函数,以钢管混凝土柱内某点开始进入塑性作为其承载力极限,由此推导出相应的承载力设计值,并将求得的结果与相关规范进行对比验证。结果表明该文提出的UST钢管混凝土柱屈服准则与相关规范求解一致,且对于压弯构件以及轴压构件等都具有很好的适用性。 相似文献
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根据具体结构的设计要求,选择适当的柱子型式和合理的截面尺寸,合理经济地做好高层建筑柱子的设计,使结构具有较好的延性和抗震性能,是高层建筑结构设计的一个十分重要的问题。基于此,本文研究了钢管混凝土结构在高层建筑柱子选型中的应用。 相似文献
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Smeared and discrete representations of localized fracture 总被引:5,自引:0,他引:5
Jan G. Rots 《International Journal of Fracture》1991,51(1):45-59
The possibilities of smeared and discrete crack concepts for simulating localized fracture in softening materials are investigated. First, comparisons are made between fixed, multi-directional and rotating smeared cracks, whereby the crack orientation is kept constant, updated in a stepwise manner or updated continuously, respectively. Next, the smeared approaches are compared to analyses on systems of predefined potential discrete cracks. Results indicate that (1) fixed smeared cracks may produce overstiff behavior while rotating smeared cracks do not, (2) smeared cracks may give rise to stress-locking while discrete cracks do not. Examples are shown for concrete and masonry. 相似文献
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The problem of estimating bounds to shakedown loads for problems governed by a class of deviatoric plasticity models including
those of Hill, von Mises, and Tresca is addressed. Assuming that an exact elastic solution is available, an upper bound to
the elastic shakedown multiplier can be obtained relatively easily using the plastic shakedown theorem. A procedure for computing
this upper bound for arbitrary load domains is presented. A number of problems are then examined and it is found that the
elastic shakedown factor is given as the minimum of the plastic shakedown factor and the classical limit load factor. Finally,
some exact solutions to a number of two dimensional problems are given. 相似文献
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Modeling the material behavior and estimation of the cracking capacity of concrete dams under the dynamic loading is important for safety operation purposes. In the present paper, an improved 3D co-axial rotating smeared crack model is used with the ability of updating the variable shear transfer coefficient. The model is implemented in the finite element code to assess the seismic cracking of three types of concrete dams, i.e. gravity, buttress, and arch dams.Results of the crack profiles confirm importance of the shear transfer coefficient in dynamic analysis of large concrete structures. It is found that the proposed model lead to less diffused cracks in concrete dams and can reasonably matches with the results obtained from experimental tests. 相似文献
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Thomas Vojta 《Journal of Low Temperature Physics》2010,161(1-2):299-323
In this paper, we review theoretical and experimental research on rare region effects at quantum phase transitions in disordered itinerant electron systems. After summarizing a few basic concepts about phase transitions in the presence of quenched randomness, we introduce the idea of rare regions and discuss their importance. We then analyze in detail the different phenomena that can arise at magnetic quantum phase transitions in disordered metals, including quantum Griffiths singularities, smeared phase transitions, and cluster-glass formation. For each scenario, we discuss the resulting phase diagram and summarize the behavior of various observables. We then review several recent experiments that provide examples of these rare region phenomena. We conclude by discussing limitations of current approaches and open questions. 相似文献
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目的 研究7055铝合金高温流变行为,建立高精度流变本构模型和有限元分析(Finite Element Analysis,FEA)仿真模型。方法 基于Gholamzadeh温度修正模型和Evans摩擦修正模型,计算修正7055铝合金热压缩流动应力,以排除试验过程中变形温升和摩擦对流动应力的影响;针对修正后的流动应力构建Johnson–Cook本构模型,依托MATLAB编程采用遍历法优化模型参考条件,并引入遗传算法(Genetic Algorithm,GA)对模型参数进行优化,通过流动应力子程序二次开发实现优化后的模型在商用软件DEFORM中的应用,以预测变形工件的应力应变分布与成形载荷。结果 经温度和摩擦修正的流动应力与试验值相近;采用遍历法优选参考条件后的Johnson–Cook本构模型流动应力预测值与试验值之间的平均相对误差绝对值(Average Absolute Relative Error,AARE)为4.57%,经GA优化后降至3.50%,实现了精度的提升。基于该模型二次开发的DEFORM模拟平台能准确预测成形载荷,预测值与试验值之间的AARE为2.42%。结论构建了具有较高... 相似文献