非均匀受压矩形钢管混凝土局部弹性屈曲分析

应用不同的特征函数描述了矩形板在非均匀压力作用下的屈曲形态,解决了采用三角级数为屈曲函数模拟非均匀受压荷载作用下单侧表面约束矩形板件屈曲模态的不对称问题;通过伽辽金法建立屈曲控制方程组,分析了非均匀荷载作用对矩形钢管混凝土构件局部弹性屈曲性能的影响。结果表明:钢管屈曲系数随着不均匀荷载梯度α增加而增大,纯弯作用下（α=2）的板件弹性屈曲荷载特征值约为轴压作用下的6倍;钢板的宽厚比限值随不均匀加载梯度α的增大而增加;非均匀荷载作用下非加载边固支约束板件的屈曲系数明显大于简支约束的板件。     

不锈钢芯板结构T形柱轴压性能有限元分析

为探究不锈钢芯板结构作为柱或梁的可行性,研究肢长、面板厚度和芯管壁厚对不锈钢芯板T形柱在轴压作用下稳定性的影响,结合已经完成的不锈钢芯板结构侧压试验,通过有限元计算软件ABAQUS对不锈钢芯板T形柱的轴压性能进行特征值屈曲分析和非线性屈曲分析。研究表明:T形柱的屈曲模式表现为面板局部屈曲;肢长对稳定承载力有很大影响;随着面板厚度的增大,芯管对面板的约束越来越弱,对其稳定承载力的贡献越来越小;芯管能给面板提供支撑,但芯管壁厚到达一定程度后,厚度的增加对稳定承载力的提升作用不大。     

基于MATLAB的螺旋输送机优化设计

以螺旋输送机为研究对象,建立螺旋体的质量目标函数,以螺旋体的结构参数为设计变量,建立目标约束函数,利用MATLAB优化工具箱对目标函数进行求解。优化后的螺旋体质量减轻了13.7%,对螺旋输送机的优化设计具有一定的理论和实际指导意义。     

槽式太阳能集热器传热模型及性能分析

槽式太阳能集热器一维和二维传热数学模型是一组非线性代数方程,为改进求解的稳定性和计算精度,将槽式太阳能集热器一维和二维传热模型的求解看作有约束优化问题,建立了集热器传热过程求解的有约束优化数学模型,应用MATLAB软件优化函数fmincon进行求解。分析了传热流体入口温度及太阳能辐射热流密度变化对集热器性能的影响。采用fmincon函数求解集热器传热过程,计算速度快,计算过程稳定。分析表明,传热流体温度变化对集热器效率的影响大于太阳能辐射热流密度对集热器效率的影响。     

焊接工字形板梁翼缘对腹板屈曲的影响

在纯弯或纯剪分别作用下的工字形焊接板梁,在弹性范围内腹板屈曲时,翼缘会对腹板起约束作用。通过采用柱稳定特微函数的形函数,用伽勒金法计算表明,其翼缘约束作用的大小,是与翼缘和腹板的尺寸有关。     

谈屈曲约束支撑安装施工

论述了屈曲约束支撑的作用与优点,介绍了屈曲约束支撑的主要类型,针对屈曲约束支撑在安装施工中遇到的问题,阐述了其在安装中的注意事项,旨在提高建筑结构在地震作用下的安全性。     

表决工程系统抗地震全局优化设计

本文在考虑地震作用时结构失效相关性情况下,研究了表决工程系统的全局优化问题。根据工 程实践的需要,提出了四类全局优化的数学模型：最优投资、最优投资分配、可靠度约束的最优投资 和可靠度约束的投资决策。在此基础上,给出了表决系统全局优化设计的一般操作过程,并通过数值 算例说明了各类优化模型的使用方法。     

人民日报社报刊综合业务楼屈曲约束支撑施工技术

人民日报社报刊综合业务楼工程属于超高层建筑,结构体系为带支撑的钢框架结构,为了提高支撑框架在地震作用下的抗震性能,采取了屈曲约束支撑技术。由于在该工程中屈曲约束支撑数量大,构件型号种类多,结合工程实际情况,详细介绍了屈曲约束支撑安装分类、安装及吊装流程和关键施工技术。通过优化施工方案,保证了屈曲约束支撑与主体结构的可靠性连接,并确保了支撑构件的受力性能和施工质量。     

基于图论与枚举算法的城市污水管网优化设计

以2008年《天津市市政工程预算基价》为依据,用遗传算法、准牛顿法和通用全局优化法拟合出污水管道和检查井的造价函数,建立了管网造价优化的完整目标函数.基于图论的原理,运用关联矩阵模拟实际某地复杂的污水管网结构,并运用MATLAB衔接其他数据,进行各方案的水力学计算.结合最大充满度的思想,运用全局优化的枚举算法,解决了陷入局部最优解问题,找到了满足各种约束条件的造价最低的管网方案.模拟结果显示,优化污水管网造价比原污水管网造价降低了11.22％.     

基于自适应动态惩罚遗传算法的桥梁监测无线测点优化研究

针对桥梁监测的无线测点优化布置问题,提出一种基于自适应动态惩罚函数的改进广义遗传算法。首先针对无线传感器数量固定和通信距离有限的典型特征将桥梁监测无线测点优化布置表达为约束优化问题,无线传感器的数量和极限传输距离作为优化问题的约束;其次构建了一种能够根据解的偏离程度和种群中高适应度个体数量自动调整惩罚力度的自适应动态惩罚函数;然后采用精英保存机制和末位淘汰策略对基于二重结构编码的广义遗传算法进行了改进;最后利用一大跨悬索桥对该方法进行了验证,并进一步讨论了自适应动态惩罚函数对解的有效性和收敛速度的影响。结果表明:提出的自适应动态惩罚函数能够根据种群的特征自动改变惩罚尺度,保证无线传感器之间的距离小于极限通信距离,同时将无线数据传输距离对桥梁监测信息获取的影响降到最低;改进的广义遗传算法具有很强的全局快速寻优能力,能够快速搜索到全局最优解,优化结果不仅能够满足无线传感网络数据传输距离的要求,还能最大化无线测点的信息获取能力。     

Design and optimization of laminated conical shells for buckling

Optimum laminate configuration for the maximum buckling load of filament-wound laminated conical shells is investigated. In the case of a laminated conical shell, the thickness and the ply orientation (the design variables) are functions of the shell coordinates, influencing both the buckling load and the weight of the structure. Thus, optimization can be performed by maximization of the buckling load for a specific weight, or by minimization of the weight of the structure under the constraint of applied buckling load. Due to the complex nature of the problem a preliminary investigation is made into the characteristic behavior of the buckling load with respect to the volume as a function of the ply orientation.The exact buckling load is calculated by means of the computer code STAGS-A (Structural Analysis of General Shells [Almroth BO, Brogan FA, Meller E, Zele F, Petersen HT. Collapse analysis for shells of general shape, user's manual for STAGS-A computer code. Technical report AFFDL TR-71-8; 1973]) by adding a user written subroutine WALL, see Ref. [Goldfeld Y, Arbocz J. Buckling of laminated conical shells taking into account the variations of the stiffness coefficients. AIAA J 2004; 42(3):642–649]. The optimization problem is solved using response surface methodology.     

Optimal stiffener design of moderately thick plates under uniaxial and biaxial compression

In this paper, the optimal stiffener design of moderately thick plates under uniaxial and biaxial compression is investigated on the premise that the plate thickness and the required ultimate strength are given. As the theoretical basis of stiffener design, the ultimate strength formulations of weak stiffened thick panels under in-plane biaxial compression are first developed on the basis of large deflection orthotropic plate theory, in which the post-weld initial deflection is taken into account. The von Mises yield criterion is employed to determine the limit state of the panel, and the Nelder-Mead simplex algorithm is used to obtain the efficient solution of nonlinear differential equations. The optimization method presented is based on the stiffener design principles of the overall instability stress and of the working stress. In the optimization formulation, the numbers and geometric sizes of the stiffeners are defined as design variables; the weight ratio of stiffeners to plate is taken as a single objective function; requirements against overall buckling of the panel, local buckling of the plates between the stiffeners and local buckling of the stiffeners themselves are set as constraint functions. Results of both design examples and parameter studies show that, for moderately thick plates, the stiffener weight given by the proposed optimization method is much lower than the weight determined by the current stiffener design method on the premise of the same requirement of structural safety. Using the present optimization method to obtain the lightest and the most effective stiffener layout for moderately thick plates is proposed.     

Structural optimization of thin-walled tubular trusses using a virtual strain energy density approach

The present paper deals with the weight minimization of tubular trusses subjected to multiple loads under size, stress and buckling constraints. The applied optimization procedure is based on a virtual strain energy density approach developed by the first two authors, already tested in plane and space truss structures. The key point of the method is the activation of at least one of the imposed displacement constraints. In case where such limitations are absent, a dummy displacement constraint is introduced instead, which iteratively sustains corrections until convergence is achieved within the desirable tolerance. The efficiency and practicability of the proposed method was tested in typical cases of tubular truss structures. For reasons of comparison, the same cases were also optimized using Sequential Quadratic Programming (SQP), which is a powerful mathematical programming optimization method. The results revealed that the proposed method performs very well in terms of convergence, of required number of iterations and of optimum tracing, while the value of the introduced dummy displacement constraint has insignificant effect on the optimization procedure.     

卵形消化池内力分析及基于遗传算法的形状优化

本文以静水压力作用下卵形消化池壳体的薄膜内力为基础 ,建立以体表面积为目标函数 ,以容积、高度 ,应力等为约束条件的优化模型。使用遗传算法对以上模型进行优化 ,并引进动态罚函数和对约束条件不断逼近的方法处理约束条件。从而为初步设计阶段卵形消化池形状的设计提供了建议和参数。     

板梁柱体系的动力分析与优化设计

基于ANSYS动力分析以及优化模块,在考虑动荷载的结构响应下,对板梁柱体系进行优化设计。建立2榀3层板梁柱体系模型,输入地震位移谱,建立动力学模型,分析动力响应。然后以结构的最大响应加速度为优化目标,以结构的最大主应力和截面的变化范围为约束条件,对结构体系截面的几何尺寸进行优化。该结果直观、可靠,可供进一步分析研究和设计参考。     

Multiobjective Optimal Design of Welded Box Beams

Abstract: The cost, mass, and maximal deflection are selected as objective functions. In the cost function, the material and fabrication costs are included. The variables are the four plate dimensions of a symmetrical welded box beam. The design constraints relate to the bending stress and local buckling of plate elements. The shear-stress constraint and size limitations are also considered. The optimal beam dimensions are computed using several single- and multiobjective optimization methods. The results of an illustrative numerical example show the effect of yield stress of steel and that of the weighting coefficients.     

Lateral-torsional buckling analysis of cantilever beam with tip lateral elastic brace under uniform and concentrated load

The studies on the lateral-torsional buckling of cantilever steel beam with tip lateral elastic brace are rarely reported. The total potential energy is first established for the lateral-torsional buckling of cantilever steel beam with tip lateral elastic brace under uniform and concentrated load. The modal trial function of the lateral displacement and torsional angle are expressed as trigonometric function combination with six terms. By introducing new dimensionless parameters, the analytical solution of the dimensionless buckling equation for the lateral-torsional buckling of cantilever steel beam with tip lateral elastic brace is obtained. With the help of 1stOpt software which is mathematical optimization analysis software, the non-dimensional critical moment formula of the lateral-torsional buckling of cantilever beam with tip lateral elastic brace is obtained. Then, the accuracy of the formula is verified by ADINA finite element software. The results show that the given critical moment formula is of high accuracy. It provides convenient and simple design method for practical engineering.     

细长桩屈曲的透明土物理模型试验研究

 采用一种在无围压条件下的1-g小规模透明土物理模拟试验,观测了不同约束形式下完全嵌入模型细长桩的完整屈曲曲线。同时,结合粒子图像测速(PIV)和近景摄影测量技术,非介入地测量了细长桩屈曲引起的土体变形。透明土由熔融石英及折射率相匹配的孔隙溶液组成。采用激光面照射透明土模型并拍摄下细长桩屈曲引起变形的数字图像,利用PIV获得所产生的位移场。试验结果分析表明：相对屈曲长度随着桩体强度增加及细长比减小而增加;桩端约束形式对屈曲曲线的影响取决于桩身强度和细长比的变化;土体单元的运动规律与经典朗肯土压力理论相一致。     

Optimization of the buckling load of columns and frames

Single buckling mode columns and frames of a given volume are optimized numerically in order to obtain the highest resistance against buckling. In the optimization process, the uniformity of the specific bending energy due to the fundamental buckling mode plays the role of the objective function. The procedure uses the finite element method (FEM) and makes use of the ANSYS program to solve the eigenvalue problem in each step of the iteration. The numerical examples analysing various configurations of columns and frames under specified loading conditions demonstrate the convergence of the procedure. Some limitations of the method are discussed as well.