建筑机械杆系钢结构的几何非线性分析

本文以杆和梁单元为例,论述了几何非线性有限单元法的基本原理及其解法,给出了杆和梁单元的刚度矩阵,并比较了几何非线性和一般的线性有限单元法的差别,最后以两个算例来说明几何非线性有限单元法在求解建筑机械钢结构杆系问题中的应用。     

大跨度桥梁极限承载力的几何与材料非线性耦合分析

介绍用几何非线性及材料非线性耦合的方法分析大跨度桥梁的极限承载力问题.几何非线性采用UL列式法,材料非线性采用分层有限单元法,两者结合达到了既保证计算精度又节省内存及机时的目的.通过算例验证,该法已被成功地应用于一座铁路悬索桥方案的极限承载力分析.     

梁-柱及柱脚均为半刚接的钢框架计算分析

针对梁-柱及柱脚均为半刚性连接钢框架进行研究,采用了考虑连接的柔性以及构件的几何非线性影响的非线性分析方法来分析和设计半刚性钢框架,给出了该种钢框架非线性分析需用的3种单元类型：考虑几何非线性的平面框架单元-梁柱单元;考虑梁端节点柔性的平面框架单元-半刚性连接梁单元;考虑底层柱脚柔性和几何非线性的底层柱单元-半刚性柱脚梁柱单元。写出了每种单元的单元刚度矩阵以及叙述了利用经典矩阵位移法进行框架整体分析的程序。引进柱脚半刚性进行钢框架非线性分析,即考虑梁柱、柱脚连接半刚性和几何非线性的整体框架分析,必然会使钢框架受力与实际状态更相符,使结构设计更合理,使框架结构的优化设计更完善、更经济。     

张拉整体四棱柱几何作图法找形与找力

张拉整体三棱柱和张拉整体四棱柱是最简单的张拉整体结构,也是形成组合式张拉整体结构的基本单元.针对端面平行张拉整体四棱柱,给出了一种几何作图找形方法.张拉整体四棱柱的自平衡内力可在找形过程中通过量测相应线段长度自然得到.通过算例对几何作图法找形和找力过程进行了详细介绍,并对找形后张拉整体四棱柱进行了有限元分析,验证了几何...     

二维离散单元法接触处理的新算法

 考虑到一个Δt 时步内系统几何构形变化并不显著的特点, 规定了块体边界节点的性质及其接触的位置排序,并提出了块间空隙几何构形的描述方法, 然后基于它们建立了二维离散单元法接触处理的新算法。新算法不仅可较大地缩短二维离散单元法的计算时间, 而且便于系统水力耦合行为的动态分析。     

无单元迦辽金法在对称叠层板弯曲问题中的应用

基于Kircihhoff板理论和对挠度函数采用滑动最小二乘近似函数进行插值,研究无单元Galerkin(EFGM)方法在对称叠层板弯曲问题中的应用.分析中,本质边界条件采用罚因子法施加,对称叠层板的无单元法几何刚度矩阵由最小二乘法和变分原理得到.通过单层方板和对称叠层板的数值算例并与其他方法的结果进行比较,表明EFGM法求解对称叠层板弯曲问题具有收敛性好、精度高等优点,从而验证了该法的有效性.     

任意凸多面体间断有限单元法

对弹性力学问题,提出一种任意凸多面体间断有限单元法.用间断分片可微的函数来近似未知位移场.单元之间位移场的连续性要求是用罚函数来实现的,其中的罚数具有明确的几何意义,并可按对解的精度要求预先估计出大小.最后用数值算例验证了所提出的方法及有关结论.     

大跨度屋面桁架吊点布置和支承卸载有限元模拟分析

某剧场为66 m的大跨度圆形桁架结构,由于施工条件限制,考虑将圆形屋盖划分为4个单元结构;每个单元结构为不规则的型钢桁架,通过MIDAS软件计算分析吊装过程中单元的刚度和强度的变化,判断是否满足施工要求.为明确单元最佳吊点位置,利用重心位置定义法计算单元重心位置;单元结构选取4个吊耳布置点,布置点形成的四边形几何中心点...     

国际期刊导读

应用于低阶四面体单元应力、应变有限元分析的稳定混合方程;基于有限元分析的桥梁建设阶段风险概率分析;Timoshenko精确法在悬臂梁适应性分析中的应用;利用四边形面积坐标法构建的4结点膜单元的几何非线性分析     

KINEMATICAL ELEMENT METHOD AND SLOPE STABILITY ANALYSIS

运动单元方法通过引进单元运动分析、 静力分析和优化求极值分析,自动完成岩土工程剪切破坏区和最危险滑动面的搜索,在此基础上求得不同工程问题的极限值。 该方法具有严格的数学力学基础,适用于各类地质条件、 岩性和几何形状复杂的岩土工程的极限分析。 运动单元法是一种分析岩土工程地基极限承载、 挡土墙极限土压以及边坡稳定性的塑性极限分析方法。 介绍了运动单元法的基本理论体系,对运动单元法边坡稳定性分析的原理与方法进行了详细论述。     

An elastic–plastic analysis of large deflection of thin shell structure using a delta-sequence function

The analysis of thin shell under large deflection has complex problem associated with the geometrical and material nonlinearities, in which the solutions for stress and deformation are desired to obtain the same level accuracy. One of ordinary and powerful method for this subject is a finite element method that has generally inconvenience to be necessarily extensive calculation due to large number of freedom.This paper is concerned with the elastic–plastic analysis of thin shell structures by the hybrid method using a functional for the principle of modified complementary energy. For elastic–plastic materials, the numerical calculation could be well executed by the way that the stress distribution across the panel thickness is expressed as continuous function using the delta-sequence function. This approach introduces a considerable way for the reduction of computing volume. The proposed method was applied to discuss the resisting mechanism of thin shell structure under large deflection.     

火灾作用下混凝土双向简支板的挠度计算

小挠度薄板理论可以用来确定混凝土双向板正常使用时的挠度,当用于计算火灾作用下处于大挠度的双向混凝土板挠度时则会带来很大误差。在引入弹性板的大挠度微分控制方程后,考虑外加荷载与高温的共同作用,并计及高温下材料特性的变化,对火灾作用下钢筋混凝土双向简支板的挠度随温度的变化进行了分析。引入无量纲量,对大挠度微分控制方程进行无量纲化处理,并以无量纲板均布荷载为摄动参数,结合Galerkin方法提出了钢筋混凝土双向简支板火灾作用下挠度的计算式,计算结果与试验结果吻合较好,可为火灾作用下板的大挠度分析提供依据。研究结果表明：火灾作用下混凝土板的挠度与外加荷载和热弯矩均有关,与热弯矩成线性关系,而与外荷载则成非线性关系;当没有热弯矩时,挠度主要由外加荷载确定;当外加荷载恒定时,挠度则主要由热弯矩引起。     

弹性地基矩形薄板弯曲问题的新解析法

目前弹性地基矩形薄板弯曲问题的解析解法,一般采用相应齐次微分方程解加特解的方式选定位移函数,本文采用了新的方法选择位移函数,将其应用范围推广到了非均匀弹性地基矩形薄板弯曲问题.以四边固定正方形薄板为例进行了计算.其理论简单,计算容易,并适合于实际工程.     

The effect of thermo-mechanical coupling for a simply supported orthotropic rectangular plate on non-linear dynamics

This paper is presented for the analysis of the large amplitude thermo-mechanically coupled vibration of the simply supported orthotropic rectangular thin plate. The governing partial differential equation of the large deflection orthotropic rectangular thin plate of thermo-mechanical coupling is derived and simplified to a set of three non-linear ordinary differential equations by the Galerkin method. The modeling result of numerical simulation indicated that the amplitude of the simply supported orthotropic rectangular thin plate decays under the various parameters of orthotropic materials. As these thermo-mechanical coupling factor, percentage of the Poisson ratio, percentage of the thermal conductance of the plate, percentage of the coefficient of thermal expansion, external in-plane force are decreased, the thermo mechanical damping of plate would be increased. The different thermal damping of the simply supported orthotropic plate can be controlled in the special range of the parameter.     

开孔薄板过屈曲分析的边界元法

从开孔薄板大挠度问题的一般数学理论出发．建立了一组新型边界积分方程用以求解开孔薄板的临界载荷、过屈曲分析。并且从分支理论出发，对离散的边界积分方程进行了分析和求解。通过算例．计算了环形板在中面内受均匀推力．横向为简支、夹紧情况下的屈曲载荷以及过屈曲状态。与已知结果吻合良好．证明边界元法对开孔薄板后屈曲状态的分析是有效的。与区域型解法比较．具有处理的矩阵维数少．输入数据量少．计算时间短等优点。     

四边简支薄壁箱体空心楼盖竖向荷载下挠度计算与分析

就薄壁箱体空心楼盖这种在大跨度大空间中广泛应用的结构体系,分别利用拟板法,差分法,ANSYS 有限元方法对其在竖向荷载作用下进行挠度计算并比较分析。对于密肋楼盖与薄壁箱体空心楼盖在混凝土用量相同的前提下,比较了二者在相同荷载条件下的工作性能。以此体现了在大跨度大空间当中,薄壁箱体空心楼盖的优点;同时,以对其工作性能的分析比较,作为薄壁箱体空心楼盖设计的基础。     

Structural design of oval-shaped sewer linings

This article describes a design method for oval-shaped sewer linings subject to external groundwater pressure. The beneficial interaction between the lining and the host structure is taken into account. The method is based on an approximate analytical solution of a clamped beam undergoing large deflection subjected to a uniformly distributed loading and in close contact with a rigid body. The method gives formulas for bending moment, axial force and maximal deflection. Thus the engineer is able to calculate a safety factor for strength and limit deflection. Comparisons with finite element analysis with large deflection and contact nonlinearities are presented for three different oval shapes. A calculation example is also treated.     

基于相似变换理论的膜张力-位移相关公式研究

以薄板的大挠度弯曲微分方程组为基础,以平面内可自由滑动、平面外无位移的局部测量范围内膜材为边界条件,推导出不同材性膜材的位移与张力对应比例关系。结合鹿岛建设株式会社的试验,得到双向等张力情况下膜张力-位移相关公式,该公式适用于各向同性与正交异性的膜材。ANSYS有限元验证表明,该公式具有很高的精度,可以满足工程需要。     

网架钢结构施工缺陷分析与处理

通过对网架钢结构常见的施工缺陷进行总结,结合实际工程针对不同的缺陷类型提出了相应的整改加固措施,并验证了整改加固效果.重点采用有限元计算的方法,分析了安装误差和杆件初始弯曲对网架钢结构的影响.分析结果表明：安装误差可能会对网架钢结构造成不安全影响,从网架钢结构的安全性出发应采用有效方法评估安装误差对结构的影响;而杆件过大的初始弯曲将显著降低杆件的稳定承载力,在施工过程中应尽量避免造成此类缺陷,对已有缺陷的杆件必须进行纠正或者更换.     

A semi-analytical method for the elastic-plastic large deflection analysis of welded steel or aluminum plating under combined in-plane and lateral pressure loads

The aim of the present paper is to develop a semi-analytical method which can quickly and accurately compute the elastic–plastic large deflection response of welded steel or aluminum plating under a combination of biaxial compression/tension, biaxial in-plane bending, edge shear and lateral pressure loads, until the ultimate limit state is reached. The post-weld initial imperfections (i.e. initial deflection and residual stresses) are included in the method as parameters of influence. It is assumed that the plating is simply supported at all (four) edges which are kept straight. A unique feature of the developed method is that geometric nonlinearity associated with large deflection response of plating under combined loads is treated by analytically solving the nonlinear governing differential equations of the elastic large deflection plate theory, while material nonlinearity due to plasticity is dealt with implicitly by a numerical procedure. This approach reduces the magnitude of numerical computations, resulting in a saving of modeling effort and computing time. As another contribution, this paper investigates and discusses the ultimate strength characteristics of plating, by varying the plate properties and load combinations, based on elastic–plastic large deflection analysis using the developed method.