建筑结构动力弹塑性分析软件计算对比及选择

比较了6个常用动力弹塑性分析软件的计算模型和结果,并分析比较了弹塑性计算结果与拟静力试验结果的差异,塑性铰模型和纤维束模型在模拟梁、柱构件上的差异,以及纤维束模型、壳元损伤模型和弹塑性墙元模型在模拟剪力墙构件上的差异。工程算例表明,各软件计算的框架结构变形和动力特性基本一致,但剪力墙结构存在一定差异。最后给出4点建议供选择弹塑性时程分析软件时参考。     

空间钢框架结构的弹塑性稳定

本文根据Giberson弹塑性梁单元模型和总势能最小值原理,导出了空间受力杆单元的二阶弹塑性切线刚度矩阵,并建立了空间钢框架结构的二阶弹塑性分析亢法。空间受力杆和缩尺空间框架模型的试验结果不仅验证了本文理论分析方法的正确性,而且反映空间结构的一些受力特性。     

循环加卸载下煤的黏弹塑性蠕变本构关系研究

 基于岩石三轴循环加卸载蠕变试验,对试样的蠕变应变进行有效的黏弹塑性应变分离,根据试样的弹性蠕变特性和塑性蠕变特性分别建立相应的蠕变模型,继而得到岩石的黏弹塑性蠕变模型,该模型能较好地描述试样的衰减和稳态蠕变特性。为了能够较好地描述岩石加速蠕变特性,在塑性蠕变模型中引入损伤因素,建立相应的弹塑性损伤蠕变模型,对该模型参数进行敏感性分析,同时给出模型参数确定方法。所建模型黏弹塑性概念清晰,模型参数较少。对煤进行三轴循环加卸载蠕变试验,分析蠕变试验中煤样的弹塑性应变特性以及试样的稳态蠕变速率演化规律,用该黏弹塑性蠕变模型对煤样的三轴压缩蠕变试验结果进行拟合,结果表明,该模型能很好地描述循环加卸载路径下试样的弹塑性加载和弹性卸载蠕变特性。     

基于改进CM模型的土石坝三维弹塑性地震反应分析

基于交变移动性（CM）模型,引入饱和度作为状态变量,给出了改进的土体塑性势面方程、屈服方程和协调方程,推导了新的硬化参量计算公式,发展了可连续描述非饱和与饱和土体静动力学特性的弹塑性本构模型。通过转换应力法,将模型从试验应力状态拓展到一般应力状态,使得本构模型可用于复杂三维河谷场地上修建的土石坝的弹塑性地震反应分析。数值模拟了汶川地震中典型震损土石坝的震害过程,模拟结果与实际震害吻合较好。对比研究了输入地震动强度对土石坝弹塑性地震反应分析结果的影响,结果表明土体的弹塑性特性对坝-基动力相互作用有着较大影响。     

双线性单自由度体系(SDOF)弹塑性位移比的研究

本文分析了双线性单自由度体系(SDOF)在地震作用下弹塑性位移与弹性位移之间的关系。对大量地震动记录下的弹塑性位移比进行了统计分析,考虑了场地土情况、震级、震中距以及滞回特性等多种因素对均值弹塑性位移比的影响,得到弹塑性位移比的回归公式。分析结果显示,场地土情况对弹塑性位移比的影响比较明显;震级、震中距以及结构阻尼对弹塑性位移比的影响不是很明显;而在短周期(<0.3s)阶段,滞回特性尤其是捏缩效应对弹塑性位移比的影响很明显。     

某双塔连体高层结构的动力弹塑性分析

针对某一双塔连体高层结构工程,采用ABAQUS软件建立三维弹塑性仿真模型,并进行了中震地震作用下结构的弹塑性分析.通过对计算结果的分析整理,初步掌握了该双塔连体结构在地震作用下的动力特性,为深化结构设计和加强薄弱部位提供了依据.     

东莞海德广场双塔连体高层结构动力弹塑性分析

采用ABAQUS软件建立三维弹塑性模型,对160.4m高东莞海德广场双塔连体高层结构进行了罕遇地震下弹塑性时程分析。通过对计算结果的分析整理,初步掌握了该双塔连体结构在罕遇地震下的动力特性,为深化结构设计和加强薄弱部位提供了依据。     

剪切刚度层模型恢复力特性骨架线的简化计算法

本文提出了确定剪切刚度层模型恢复力特性骨架线的简化计算法。以北京国贸中心高层钢结构为例，用简化法和弹塑性荷载增量法计算了层恢复力特性骨架线，用这两种骨架线进行了弹塑性时程分析，两者的结果比较接近。简化法确定的骨架线适用于高层建筑钢结构在大震作用下的安全验算。     

某超高层静力和动力弹塑性分析对比

该文通过对某高于200 m的超高层进行静力和动力弹塑性分析,阐述了该结构的静力和动力特性,强化了静力、动力弹塑性分析认识。     

桩筏基础桩-土相互作用的数值分析

利用ABAQUS对3D桩距和6D桩距的桩筏基础进行了三维弹塑性分析.通过无厚度的接触面单元模拟桩-土之间的非线性接触特性,采用Mohr-Coulomb弹塑性本构模型描述土的非线性特性,桩取为弹性,得到了沉降、桩土荷载分担比、板底土附加应力等变化情况,并对二者进行了对比分析.分析结果基本反映了桩-土-筏的实际工作性状,验证了复合桩基理论的正确性.     

A multi-camera based photogrammetric method for three-dimensional full-field displacement measurements of geosynthetics during tensile test

Conventional methods for measuring the deformational response of geosynthetics, such as the linear variable differential transformers (LVDTs), strain gauges, and extensometers have several limitations in fully determining the complete strain distribution in geosynthetics. This paper presents a multi-camera based photogrammetric method to track the 3D full-field displacements of geosynthetics during tensile tests. The proposed method extends the conventional one-camera based photogrammetry for static object measurements to multi-camera-based photogrammetry for object measurements with continuous movements or deformations. It is non-contact, cost-effective, highly accurate, and capable of measuring the 3D full-field displacements of the geosynthetics. A tensile test on a geogrid specimen was performed to verify the effectiveness and accuracy of the proposed photogrammetric method. The results from the tensile tests using both the proposed method and conventional methods, such as machine-controlled displacement measurements and extensometer, were presented and compared. It was observed that the average absolute difference between the proposed photogrammetric method and the machine-controlled movements of the bottom clamp was 0.25%, and the average absolute error was 0.038 mm. The average difference in measurements made by the proposed method and extensometer was 0.07%. It was further found that the proposed method can provide more comprehensive input, such as the complete strain and modulus distributions in the geosynthetics, for a probability-based geosynthetics design.     

Creep behaviour of geosynthetics

Empirical results dealing with rheological properties of some geosynthetics are presented. Creep tests performed on some Polish-made geotextiles are described and discussed within the framework of the standard linear solid (SLS) model. It is shown that the SLS model described by three parameters can serve as a useful low resolution approximation for a range of geosynthetics, for low stress levels which exclude secondary and tertiary creep. The parameters of the SLS model were determined by curve fitting for three types of Polish geotextiles as well as for some other geosynthetics. The problems of creep under increasing load and creep after partial unloading are discussed. Two modified rheological models of geotextiles, which take into account the plastic strains, are proposed.     

土工布加筋基础的一维非线性模型(英文)

本文推导出一个代表软土双曲线弹簧支撑的土工布加筋基础一维非线性模型。该模型的数学形式是两个非线性二阶常微分方程组。给出了解常微分方程组的迭代格式，并着重讨论了非线性弹簧参数对加筋基础的沉降和土工布拉力的影响。     

水平地震作用下双级加筋土挡墙格栅应变及破裂面分析

基于大型振动台模型试验,研究水平地震荷载作用下双级土工格栅加筋土挡墙的格栅应变和潜在破裂面规律。用福建砂作为回填砂、混凝土砌块作为挡墙和土工格栅作为筋材构成了试验模型。模型高度1.8 m。输入地震波为卧龙波和EL-Centro波,共9个试验工况。试验结果表明,随着峰值加速度增大,应变值增大,且应变最大值点向土体内部扩展。潜在破裂面随峰值加速度增加逐渐向土体内部扩展。综合已有破裂面计算方法,提出了考虑平台宽度的双级折线型破裂面模型,模型可为双级加筋土挡墙设计计算提供参考。     

单向土工格栅加筋土的流变模型

在研究HDPE单向土工格栅的蠕变和应力松弛特性的基础上，建立了单向土工格栅的流变模型。将加筋土视为由筋、土组成的宏观均匀材料，建立单向土工格栅加筋土体的流变模型。分析表明，在承受长期荷载作用的加筋土的本构关系中，必须考虑由聚合物为原料制作的筋材所具有的明显时间相关的力学行为。     

预应力返包式加筋土挡墙的动力响应分析

在地震作用下,返包式加筋土挡墙作为一种柔性结构常因侧向变形较大或局部产生破坏而影响其正常使用。为解决该问题,提出了预应力返包式加筋土挡墙结构。为完善预应力返包式加筋土挡墙的设计理论,运用拟动力法和附加应力法理论,以预应力返包式加筋土挡墙作为研究对象,结合现有的加筋土挡墙侧向动土压力和侧向位移计算理论,提出了一套用于计算预应力返包式加筋土挡墙侧向动土压力和侧向位移的理论公式。结合室内振动台模型试验验证了所提理论方法的可行性和合理性。该方法计算简洁,适用性广,能够较好地计算预应力返包式加筋土挡墙的侧向动土压力和侧向位移,对完善预应力返包式加筋土挡墙的设计理论具有一定的指导和借鉴意义。     

Experimental study of a 3D printed geogrid embedded with FBG sensor for reinforcement of subgrade with underlying cave

Road construction in karst areas is a challenging task. Combining the advantages of geosynthetics and fiber Bragg grating (FBG), this paper creatively presents a new type of FBG-3D printed geogrid, which allows reinforcement and accurate deformation monitoring. A series of model tests were carried out to investigate the mechanical and deformation characteristics of the subgrade with underlying karst cave reinforced by FBG-3D printed geogrid. The experimental results indicated that the fully coordinated deformation between FBG sensor and geogrid was successfully achieved by 3D printing technology, and the relationship between fiber wavelength and strain was obtained. The existence of cave had an adverse effect on the subgrade, but the FBG-3D printed geogrids effectively improved the bearing capacity and footing settlement, and the reinforcement effect increased with the decrease of geogrid spacing. In the cyclic loading experiments, the earth pressure inside the subgrade reinforced by geogrid changed as a half-sine wave in each cycle. The FBG sensors accurately measured the strain change inside the subgrade, and the data showed that the deformation of measuring point above the cave model was the largest. The research conclusions provide important basic data for the construction and monitoring of highway and geotechnical engineering projects.     

加筋土结构中筋材拉拔力的分布规律研究

分析了加筋材料在拉拔试验条件下,筋材所受到的拉力、剪应力、应变之间的关系,利用筋土界面间存在的抗剪刚度系数G,建立起了与材料拉伸模量E_r和G有关的拉拔影响系数α,从而推导出拉力沿筋材分布的公式和各点筋土的相对位移公式。通过与已有的试验数据相对比,证实该公式的可行性。分析了拉力在筋材上的传播规律和α对筋材拉拔力分布的影响,表明用α能综合反映压应力、摩阻力、土体性质等多种因素对筋材拉力的影响。在加筋土结构中,筋材位移不是很大时,采用该公式能较好地估算筋材各处的拉力。     

考虑薄膜效应的土工合成材料加筋道路模型

薄膜效应是土工合成材料加筋道路的作用机理之一。在假定薄膜横向挠度很小的情况下,导出了薄膜的平衡微分方程。利用层状弹性体与薄膜竖向位移与应力的连续性将二者耦合,建立了土工合成材料加筋道路的计算模型。并以两层加筋体系为例,导出了在轴对称和非轴对称荷载作用下的一般解。     

基于修正Iwan模型的软黏土动应力–应变关系研究

在循环荷载作用下,饱和软黏土由于孔压上升和结构重塑会发生应变软化;同时会产生累积塑性应变。而且,当存在初始偏应力时,累积塑性应变的发展速率加快,并随着循环次数的增加,滞回圈明显向右滑移。正基于此,本文通过对杭州正常固结饱和软黏土进行应力控制的循环三轴试验,首先建立考虑不同动应力、初始偏应力下正常固结软黏土的软化指数经验模型;然后将软化模型引入Iwan串联模型中考虑循环软化的影响;同时再串联一理想刚塑性元件,模拟循环过程中产生的累积塑性应变;最后结合Masing准则对软黏土的动应力–应变关系进行了描述。通过对试验值进行模拟以及与其他模型的对比分析,初步证明了模型的合理性和有效性。