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根据等参元的概念推导出3结点锚杆单元及9结点的块体单元的数值计算公式,由此建立起锚杆——岩土体空间耦合分析模型,编制出相应的空间弹塑性有限元程序。作为实际应用的例子,该模型用来分析了岩土体拉拔实验,并与无锚杆作用时的弹性分析进行比较,计算出的结果证实了该模型的实用性。 相似文献
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为准确描述钢筋混凝土结构的非线性地震灾变过程,建立了一种基于显式算法可考虑地震作用应变率效应的钢筋混凝土动态纤维梁单元模型,并以材料子程序(VUMAT)的形式嵌入ABAQUS有限元分析平台中。对混凝土、钢筋以及钢筋混凝土柱动态加载试验进行了数值模拟,测试并验证该模型用于钢筋混凝土材料及构件动态性能分析的准确性和有效性。研究结果表明,所提出的钢筋混凝土动态纤维梁单元模型计算精度较高,能够准确并实时反映地震作用下应变率对材料及构件动态性能的影响,可为精确计算钢筋混凝土结构在地震作用下的非线性动力反应提供理论基础。 相似文献
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加锚岩体的三维复合单元模型研究 总被引:3,自引:1,他引:3
首先提出了复合单元的概念,然后将其应用于建立砂浆固结锚杆的分析模型。该模型考虑了岩体、砂浆、锚杆、岩体/砂浆接触面、砂浆/锚杆接触面等多重介质。借助阶谱的概念,复合单元可以纳入常规有限单元法分析中去。当某单元不含锚杆时,即退化为常规有限单元。应用该模型进行加固布设优化分析,当单元内锚杆的数量与方向改变时,计算网格无需变化,从而为大规模三维复杂结构计算分析的前处理提供较大便利。模型在有限单元软件CORE3中实现。并提供了计算实例。 相似文献
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从非连续介质力学角度出发,提出了1种能准确模拟混凝土断裂破坏过程的细观单元等效化方法,推导混凝土细观单元的等效力学行为并数值验证了其合理性。基于细观单元等效化模型,采用扩展有限元法对单轴拉伸条件下湿筛混凝土试件的裂纹扩展过程及宏观力学性能进行数值模拟,并与细观随机骨料模型结果进行对比。结果表明:与随机骨料模型相比,细观单元等效化模型大大减小了体系自由度,在较低计算量的情况下可以获得与之较吻合的裂纹扩展路径及宏观力学性能,充分展现了该力学模型的准确性和高效性。 相似文献
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加锚固体的三维复合单元模型研究 总被引:30,自引:64,他引:30
首先提出了复合单元的概念,然后将其应用于建立砂浆固结锚杆的分析模型。该模型考虑了岩体、砂浆、锚杆、岩体/砂浆接触面,砂浆/锚杆接触面等多重介绍,借助阶谱的概念,复合单元可以纳入常规有限单元法分析中去,当某单元不含锚杆时,即退化为常规有限单元。应用该模型进行加固布设优化分析,当单元内锚杆的数量与方向改变时,计算网格无需变化,从而为大规模三维复杂结构计算分析的前处理提供较大便利,模型在有限单元软件CORE3中实现,并提供了计算实例。 相似文献
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基于离散单元法的框架填充墙裂缝数值模拟 总被引:2,自引:0,他引:2
框架填充墙裂缝问题越来越受到人们的关注,通过调查,裂缝大多出现在砌块之间的灰缝处.本文采用离散单元法对框架填充墙裂缝进行数值模拟分析,建立了一个基于Cundall块体模型的矩形刚性块体离散单元模型,并详细介绍了该模型的基本原理、破坏准则、基本方程以及阻尼系数、时间步等计算参数的确定方法.通过程序对框架填充墙裂缝开展的数值模拟,得到了裂缝开展的规律. 相似文献
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针对某自锚式悬索桥的钢箱梁分别采用壳单元、铁摩辛柯梁单元和欧拉—贝努力梁单元进行了对比研究,以便得到该桥有限元分析的合理模型。在结构自重条件下,将三种有限元模型的Mises应力计算结果与四个实测结果进行对比。结果表明,壳单元模型的计算结果接近实测结果,是自锚式悬索桥钢箱梁分析的合理单元。 相似文献
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综合单价风险量化研究 总被引:4,自引:0,他引:4
刘静 《四川建筑科学研究》2006,32(4):187-189
自实行工程量清单计价以来,综合单价风险一直是一个不被投标人重视,甚至是忽略了的问题。此研究从风险对投标报价的影响出发,详细阐述了综合单价中风险的定义;通过对综合单价的分解,分析了综合单价风险的内容;建立了两种简便易行的综合单价风险计算的数学模型——分项计算法和综合系数法,解决了风险如何量化的问题;提出了防范报价风险的对策,对降低企业投标报价的风险,提高工程经济效益具有积极的意义。 相似文献
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基于单元式玻璃幕墙的整体性特点,考虑玻璃与骨架的协同工作效应,提出了玻璃与骨架协同工作的计算方法;基于此方法,经过对实际工程的数值模拟分析,认为适当考虑玻璃的刚度贡献是比较合理的,也是经济的。 相似文献
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本文对某火力发电厂300MW汽轮发电机组框架式基础进行缩尺比为1/8的模型振动试验,通过模型振动试验,根据相似关系换算得到原型结构的自振频率、振型和振动线位移。在模型试验测试中,分别进行了无机组设备质量工况、有机组设备质量工况和扰力点动刚度测试。对测试结果进行分析得知,机组设备质量的施加使得结构的各阶自振频率降低。使用TGFP、SAP2000和ANSYS软件建立模拟轴系影响的计算模型,进行结构的模态和稳态分析,得到了基础结构的自振频率、振型和振动线位移。计算的扰力点幅频曲线与试验结果有较好的吻合。 相似文献
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Xiaohui Dong Zhenyun Tang Xiuli Du 《The Structural Design of Tall and Special Buildings》2023,32(18):e2055
Real-time hybrid simulation is a testing method that combines physical experiments and numerical simulations, which can increase the dimensions of experimental specimens and reduce the error of scaling testing. Currently, the maximum degrees of freedom of numerical models are 7000 in real time. To improve the scale of numerical simulation in real time, a testing framework based on Python and graphics processing unit was proposed in this paper. The maximum degrees of freedom of the numerical model exceeded 24,000 with the testing framework. The testing capacity of real-time hybrid simulation was significantly improved by the graphics processing unit calculations. 相似文献
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结合计算实例采用空间六面体八节点等参单元,在分缝处定义不抗拉单元来计算分缝部位的应力场,同时针对该问题运用ANSYS模型在分缝处施加不抗拉的杆单元做类似分析,使两种结果相互检验,结果指出这两种方法均可适用于对各类低抗拉单元的分析。 相似文献
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Soil-cement deep mixing (DM) columns combined with geosynthetic basal reinforcement are an accepted technique in geotechnical engineering to construct road and railway embankments over soft foundations. Both full-width and unit cell models have been used to numerically simulate the performance of geosynthetic-reinforced and column-supported (GRCS) embankments. However, the typical unit cell model with horizontally fixed side boundaries cannot simulate the lateral spreading of the embankment fill and foundation soil. As a result, the calculated reinforcement tensile loads using typical unit cell models are much less than those from matching full-width models. The paper first examines GRCS embankments using a full-width model with small- and large-strain modes in FLAC and then compares the calculated results from the full-width model with those using a typical unit cell model, a recently proposed modified unit cell model, and a closed-form solution. The paper also examines the influence of the soft foundation soil modulus, reinforcement tensile stiffness, and DM column modulus on the reinforcement tensile loads. Numerical analyses show that the reinforcement tensile loads from the modified unit cell model are in good agreement with those from the full-width model for zones under the embankment crest for all cases and conditions examined in the paper. Both the full-width model and modified unit cell model perform better than the typical unit cell model for the prediction of the reinforcement tensile load when compared to the closed-form solution. However, while the modified unit cell developed by the writers is shown to be more accurate than the typical unit cell when predictions are compared to results using full-width numerical simulations, the benefit of using this approach to reduce computation times may be limited in practice. 相似文献
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Prefabrication of modular residential and office units involves rapid manufacturing various building components off-site from different choices of materials, and transportation to construction site for the complete assembly. While this prefabrication manufacturing process could reduce construction costs, time and waste by using lightweight composite modules (LCM), significant challenge is associated with fire performance of an office modular unit using the modular units. This work aims at investigating the fire performance of a modular office unit using the LCM in terms of heat release rate and temperature history and compared with the traditional office unit model using glazing facade. The heat release and flame propagations in a selected prefabricated modular office unit are simulated with computational fluid dynamic (CFD) taking into account the complexity of the materials systems and the influences of the facade. The numerical procedure combining pyrolysis analysis of the composite sandwiches and the fire dynamic simulation of the combustion process is developed. The computational model is validated with thermal responses obtained from the cone calorimetry experiments. Kinetic parameters obtained from the TGA tests and pyrolysis analysis are used as inputs for the models measuring the fire growth index and total heat release. A multilayer sandwich composite material model is proposed to simulate the thermal responses and combustion processes of the prefabricated unit envelop. Temperatures at critical locations of the units are captured and compared with the standard fire curve to reveal the significant improvement in the fire performance of the office modular unit utilising GFRP composite. 相似文献
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建立了组合梁极限承载力有限元分析模型,对组合梁粘贴CFRP加固前、后的性能进行了分析,并利用此分析方法与一些相关的CFRP板加固组合梁实验结果进行分析对比,结果显示,计算结果与实验结果吻合较好,表明计算方法具有较高的精度。 相似文献