多目标群智能杂交算法及双层球面网壳动力优化

为了改善多目标粒子群算法在结构多目标优化中的收敛精度和速度,提出了一种新型多目标算法——基于启发式粒子群算法和遗传算法的多目标杂交算法(MHGHA).以双层网壳结构为研究对象,对其在地震作用下的时程响应进行分析,以结构节点最大位移最小化和结构质量最轻化为目标进行多目标优化设计,并与经典算法进行对比.结果表明,杂交算法的收敛精度更高,同时能够实现复杂空间结构多目标优化.     

基于杆件构形刚度参数均匀化的单层网壳稳定性能优化

为实现网壳各节点抵抗荷载能力的均匀分布,提升结构稳定承载力,基于网壳结构受力特点,引入了单层网壳结构的杆件构形刚度参数。以结构杆件构形刚度均匀化为目标,将网壳杆件截面尺寸作为优化变量,采用惯性权重改进后的粒子群算法对网壳的杆件截面进行优化配置。优化结果表明,构形刚度方差能较为准确地反映结构的杆件构形刚度均匀程度。通过粒子群算法优化后求得的杆件配置可以使网壳结构接近于等稳定性,最大程度地提升结构的稳定极限承载力。     

单层球面网壳选型优化设计

采用改进的自适应遗传算法来解决单层球面网壳结构构件截面优化问题,并采用VC＋＋语言编写了相应的自适应遗传算法和有限元计算程序,可以实现单层球面网壳结构的自动优化设计。设计了不同类型、跨度和矢跨比的网壳优化算例;并通过对按照现行相关规范优化设计的单层球面网壳和符合现行相关规范要求但未经优化设计的单层球面网壳用ANSYS软件进行考虑几何非线性的屈曲分析,分别确定其屈曲荷载与设计荷载之比,以比较它们的受力和安全性能。结果表明采用自适应遗传算法进行离散变量的网壳结构截面优化设计容易收敛,优化效果良好。如果综合考虑经济和安全因素,设计网壳时,其矢跨比取1／6～1／5比较合适。     

单层网壳结构弹塑性稳定性和优化设计研究

以民航博物馆不规则连续单层网壳结构为例,对单层网壳考虑弹塑性稳定性和优化设计进行探讨。比较了各荷载工况作用下的几何非线性极限承载力、弹塑性非线性极限承载力与荷载标准值之比和线弹性外力势能的分布规律,初步探讨了在诸多荷载组合工况中选择单层网壳结构弹塑性稳定极限承载力控制工况的方法。探讨单层网壳考虑弹塑性稳定优化设计的实用简化方法,提出了杆件截面优化的应力比缩减分层法,使复杂的优化设计问题简单化。     

单层球面网壳的优化设计

提出了针对单层球面网壳结构的一种优化设计方法,它是一种以网壳的总造价为目标函数,取网壳的网格数、矢高、杆件截面面积和节点体积作为优化设计变量,采取直接搜索法与准则法相结合的优化设计方法.基于用Fortran90软件编制的优化设计程序,对单层球面网壳结构进行了大量的计算,用回归分析得出网壳最优网格数、矢高、杆件截面面积和节点体积,同时使杆件面积规格化,以便直接用于实际工程.     

单层球面网壳的优化设计

提出了单层球面网壳结构的一种优化设计方法 ,它是一种以网壳的总造价为目标函数 ,取网壳的网格数、矢高、杆件截面面积和节点体积作为优化设计变量 ,采取直接搜索法与准则法相结合的优化设计方法 .基于用 Fortran90软件编制的优化设计程序 ,对单层球面网壳结构进行了大量的计算 ,用回归分析得出网壳最优网格数、矢高、杆件截面面积和节点体积 ,同时使杆件面积规格化 ,以便直接用于实际工程     

单层球面网壳的优化分析

应用ANSYS软件优化模块,以自重最轻为目标函数,以强度、稳定性等为约束条件,并考虑了结构几何非线性的影响,对凯威特型单层球面网壳进行优化分析。然后对优化所得的网壳作了稳定性全过程分析,从而验证优化设计是可靠的。     

考虑整体稳定的单层网壳截面优化设计

整体稳定性是单层网壳结构设计中的一个关键问题.在进行此类结构的优化时,必须考虑整体稳定性的影响才能得到符合规程要求的设计.本文综合考虑了位移、应力和杆件稳定以及结构整体稳定性条件,提出了基于最优准则法的优化设计方法,可按照钢结构设计规范和网壳结构规程的要求,对单层网壳结构进行杆件截面设计.     

局部单双层网壳火灾工况下受力分析

针对工程实例的特定条件,应用ANSYS有限元分析软件进行局部单双层网壳火灾工况下的受力分析和热力耦合分析,比较局部单双层网壳结构在火灾工况下的受力情况与常温态下的不同。以8个初始模型的组合变量为样本并以极限承载力为目标进行回归分析,通过回归分析对该结构进行优化设计,证明火灾荷载参与结构优化设计的可行性,为今后的深度优化提供思路。     

基于风洞试验成果的大跨度网壳结构优化

以某大跨度网壳结构为研究对象,对建筑结构进行了风洞试验.将风洞试验体型系数结果引入大跨度网壳结构并优化设计.应用复形法建立了网壳结构目标函数,初步拟定网壳结构的网格尺寸、网壳厚度、网壳矢高,以杆件的截面面积为设计变量,杆件的强度和最小截面尺寸为约束条件,并编制了相应的程序,对三圆弧网壳结构外形尺寸进行多种方案的优化设计,比较试验与规范风载体型系数优化结果,为类似网壳结构设计提供参考.     

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

This study proposes a shape optimization method for K6 aluminum alloy spherical reticulated shells with gusset joints, considering geometric, material, and joint stiffness nonlinearities. The optimization procedure adopts a genetic algorithm in which the elastoplastic non-linear buckling load is selected as the objective function to be maximized. By confinement of the adjustment range of the controlling points, optimization results have enabled a path toward achieving a larger elastoplastic non-linear buckling load without changing the macroscopic shape of the structure. A numerical example is provided to demonstrate the effectiveness of the proposed method. In addition, the variation in structural performance during optimization is illustrated. Through parametric analysis, practical design tables containing the parameters of the optimized shape are obtained for aluminum alloy spherical shells with common geometric parameters. To explore the effect of material nonlinearity, the optimal shapes obtained based on considering and not considering material non-linear objective functions, the elastoplastic and elastic non-linear buckling loads, are compared.     

Multi-objective optimal design of braced frames using hybrid genetic and ant colony optimization

In this article, multi-objective optimization of braced frames is investigated using a novel hybrid algorithm. Initially, the applied evolutionary algorithms, ant colony optimization (ACO) and genetic algorithm (GA) are reviewed, followed by developing the hybrid method. A dynamic hybridization of GA and ACO is proposed as a novel hybrid method which does not appear in the literature for optimal design of steel braced frames. Not only the cross section of the beams, columns and braces are considered to be the design variables, but also the topologies of the braces are taken into account as additional design variables. The hybrid algorithm explores the whole design space for optimum solutions. Weight and maximum displacement of the structure are employed as the objective functions for multi-objective optimal design. Subsequently, using the weighted sum method (WSM), the two objective problem are converted to a single objective optimization problem and the proposed hybrid genetic ant colony algorithm (HGAC) is developed for optimal design. Assuming different combination for weight coefficients, a trade-off between the two objectives are obtained in the numerical example section. To make the final decision easier for designers, related constraint is applied to obtain practical topologies. The achieved results show the capability of HGAC to find optimal topologies and sections for the elements.     

基于遗传算法的飞艇结构多目标优化

首先,根据软式飞艇结构的力学特点建立了飞艇结构的多目标优化模型,以外荷载作用下飞艇“应力最小”、“变形最小”及“自重最小”为优化目标,确定膜材厚度、膜材弹性模量、飞艇内气压及飞艇细长比为优化变量.其次通过加权系数法将多目标优化转化为单目标问题,并采用遗传算法进行求解.最后,采用此方法对某一飞艇结构进行多目标优化.研究结果表明：飞艇的优化模型是有效的;结合加权系数法和遗传算法,可以获得各个目标均较理想的优化结果;通过进行多目标优化可以为飞艇结构的设计提供合理建议.     

Structural analysis of Pareto-optimal solution sets for multi-objective optimization: An application to outer window design problems using Multiple Objective Genetic Algorithms

In single-objective optimization problems, with only one optimal design objective, the absolute optimal solution to maximize/minimize the objective function can be determined. However, in most real design problems, the optimization problems are multi-objective, where two or more independent design objectives must be optimized simultaneously, and no single absolute optimal solution necessarily exists. In these cases, it is helpful for designers to recognize the range of alternative solutions that exist in Pareto-optimal sets and choose an acceptable solution from among them. In this paper, the authors carried out multi-objective optimization using Multiple Objective Genetic Algorithms through a real case study involved in indoor environmental design – the design of outer windows. Then the authors analyzed structure of Pareto-optimal solution sets. Here we present the analysis process as well as the case study details, and show how the method proposed here is effective at finding an acceptable solution for multi-objective optimization problems.     

单层球面网壳结构抗震性能研究

本研究了单层网壳结构地震响应的计算理论和计算方法。以K8型单层球面网壳为研究对象,得出了单层网壳在水平地震作用和竖向地震作用下的力学响应特性的一些重要结论。进一步针对地震响应的主要影响参数,如结构几何参数、边界刚度、阻尼比等,对单层球面网壳地震响应规律作了系统的研究,并提出了对单层网壳结构抗震设计有应用价值的结构和建议。     

单层球面网壳在多维地震作用下的随机响应分析

采用课题组推导的多维虚拟激励理论方法及自编计算机程序，对常用K6型单层球面网壳多维地震反应规律进行了系统研究。论文首先对功率谱计算时的参数取法进行了讨论，然后对单层球面网壳进行了大量多维与单维响应对比分析，考虑了矢跨比、荷载、跨度等主要结构参数影响，给出了主肋、环杆、斜杆在不同参数下多维与单维地震反应对比规律及数值范围。分析结果表明，网壳大量主要受力杆件三维地震内力远远大于单维地震内力，得出在网壳抗震设计中必须要进行三维地震作用分析的结论。本文结果为网壳工程设计提供了参考。     

索穹顶结构预应力多目标优化的小生境遗传算法

根据索穹顶结构的柔性结构特点和力学特性,探索以质量最小、刚度最大和支座反力最小为目标函数,以预应力整体可行性准则、荷载态应力控制和位移限值为约束条件的多目标优化模型。结合自适应技术、预选择机制和共享函数小生境技术对传统遗传算法进行改进,利用加权系数法将多目标优化问题转换为单目标Pareto最优解问题。利用向量式有限元对不同预应力水平的结构进行静力分析。最后通过两个不同类型索穹顶算例,采用自编程序的计算结果证明所提出的方法是有效的,为索穹顶结构预应力优化分析提供了新的计算方法。     

基于鱼群算法的耦合地震作用下钢结构-控制系统协同优化设计

鉴于目前土木工程的结构抗震优化设计方法尚未考虑到结构设计与控制设计之间的耦合相关性,极有可能丧失系统最优解,故运用协同优化策略对钢结构与控制系统进行一体化设计。首先建立耦合地震作用下含磁流变阻尼器(MRD)的运动方程,采用瞬时最优控制策略对其进行地震响应控制;进一步建立钢结构和MRD的优化模型,采用鱼群算法处理结构和MRD的多目标优化问题。优化结果表明:经协同优化设计后的受控结构性能优于串行设计的;耦合地震作用的优化结果稍大于只考虑水平地震作用的。     

MOGA-Based Structural Design Method for Diagrid Structural Control System Subjected to Wind and Earthquake Loads

An integrated optimal structural design method for a diagrid structure and control device was developed. A multi-objective genetic algorithm was used and a 60-story diagrid building structure was developed as an example structure. Artificial wind and earthquake loads were generated to assess the wind-induced and seismic responses. A smart tuned mass damper (TMD) was used as a structural control system and an MR (magnetorheological) damper was employed to develop a smart TMD (STMD). The multi-objective genetic algorithm used five objectives including a reduction of the dynamic responses, additional stiffness and damping, mass of STMD, capacity of the MR damper for the integrated optimization of a diagrid structure and a STMD. From the proposed method, integrated optimal designs for the diagrid structure and STMD were obtained. The numerical simulation also showed that the STMD provided good control performance for reducing the wind-induced and seismic responses of a tall diagrid building structure.     

基于遗传算法的密肋复合墙体多目标优化设计方法研究

密肋复合墙体是密肋壁板结构体系的主要受力构件,墙体的优化设计方法研究是结构体系设计理论的重要组成部分。在前期研究的基础上,建立综合考虑密肋复合墙体安全性(墙体斜截面抗剪承载力)与经济性(墙体造价)的多目标优化设计数学模型,并采用遗传算法进行优化计算,最后给出了计算算例。理论分析与计算结果表明:将多目标优化设计方法用于密肋复合墙体的优化设计中,可使各个分目标都较为满意,兼顾了墙体安全性与经济性两方面的要求;方法合理、可行,对密肋复合墙体的设计有一定参考意义。