预应力混凝土井式梁板结构的优化设计

本文引入传统设计经验,将预应力砼井式梁板结构简化为合理、有效的计算模型。以作者建立的非线性有限条分析方法作为结构非线性分析工具和结构优化的序列熵迭代法对简化模型进行优化计算,使得这种大型结构建立在非线性分析之上的优化设计成为可行。文中对实际工程进行了优化计算。     

压电弹性层合梁-板结构中SH波的传播

建立了压电层合梁-板结构的压电-弹性动力学基本方程式，在给定压电层合梁-板结构形式和波传播方向的情况下，对基本方程式进行了简化；利用连续性条件和边界条件，建立了波传播的特征方程式，并对波动方程式进行求解；得到了前三阶频散关系曲线。通过实例数值计算，讨论了弹性层、压电层的厚度比与频散关系的影响，得出了SH波在压电层合梁-板结构中传播的基本特性。     

基于M-φ关系的工形PC弯曲梁的宏观分析模型

工形预应力混凝土(PC)梁在实际工程结构中的应用非常广泛,T形、倒T形和矩形梁都是工形梁的特殊简化形式,建立简单实用的工形PC梁的分析模型非常有实际意义.从材料非线性本构关系出发,通过截面分析导出工形PC截面的弯矩-曲率(M-φ)关系,由此确定沿梁长度方向所有单元的抗弯刚度,建立起考虑材料非线性的工形PC弯曲梁的宏观有限元模型.试验梁分析结果与试验数据对比表明,该模型能模拟PC弯曲梁整个加载过程的非线性结构响应.     

基于M-Ф关系的工形PC弯曲梁的宏观分析模型

工形预应力混凝土(PC)梁在实际工程结构中的应用非常广泛,T形、倒T形和矩形梁都是工形梁的特殊简化形式,建立简单实用的工形PC梁的分析模型非常有实际意义．从材料非线性本构关系出发,通过截面分析导出工形PC截面的弯矩一曲率(M-Ф)关系,由此确定沿梁长度方向所有单元的抗弯刚度,建立起考虑材料非线性的工形PC弯曲梁的宏观有限元模型．试验梁分析结果与试验数据对比表明,该模型能模拟PC弯曲梁整个加载过程的非线性结构响应．     

化爆作用下无梁板结构的冲切动力响应分析

在化爆土中自由场波传播理论的基础上,采用介质结构相互作用理论和双剪强度理论对无梁板结构冲切破坏机构进行了分析,建立了无梁板结构的冲切抗力模型和动力响应方程,分析结果与试验结果符合较好。     

高层筒体结构井式梁与筒壁相交端应力分析

本文应用ＳＡＰ９１结构分析软件，对某制麦塔圆筒体结构进行了有限元分析计算，通过计算指出了筒体结构中井式梁与筒壁相交端的应力最大处，为工程结构设计提供了依据。     

人行激励下梁板结构与人体耦合作用研究

对于重要的梁板结构,应该考虑人行激励下的结构振动以及人体舒适度问题.根据单步落足曲线将人体等效为具有主体部分和耦合质量的时变动力模型,并建立了梁板结构与移动人体相耦合的动力平衡方程及其解析表达式.考虑行走速度和楼板长度等因素,按耦合分析方法对人体与结构的动力响应进行了研究和比较,结果表明人体的自振频率、行走步频和速度是影响结构动力响应和人体的舒适度的重要因素,在梁板结构设计时需要充分考虑上述因素从而有效降低结构振动强度.与等效静力法和不考虑人体耦合作用的动力方法相比,本文提出的动力耦合分析方法更加全面和准确.     

基于p-y曲线法的高桩码头全结构段和单排架模型对比研究

以某钢筋混凝土高桩梁板结构为例,基于p-y曲线法,采用ANSYS建立了全结构段和单排架模型。施加相应荷载组合,对两种模型的桩基内力进行了对比。通过调整单排架中船舶撞击力在排架中的分配系数,对比单排架的桩基和横梁内力与全结构段的误差。所得结果说明,规范中规定的横向水平力在排架中的分项系数不适用于三维有限元梁板结构。结论对高桩码头内力计算有参考价值。     

爆炸荷载作用下钢筋混凝土梁板结构的面力效应

为了研究爆炸荷载作用下钢筋混凝土梁板结构的面力效应,该文在钢筋混凝土梁板结构面力效应的静力分析模型基础上,结合弹粘塑性应变速率本构模型,将面力效应的静力分析模型推广应用于动载作用情况,采用单自由度法建立了考虑面力效应的钢筋混凝土梁板结构的动抗力模型,并编制了计算程序,理论计算结果与试验数据吻合较好。此外,利用所提出的分析方法对抗爆结构中常见的典型核爆和化爆荷载作用下的荷载的加载速率、轴向约束刚度和配筋率等主要影响因素进行了分析讨论,并指出:钢筋混凝土结构的面力效应随着加载速率、边界约束强度的提高和配筋率的降低而增强;动抗力提高程度越大,塑性变形也越大。     

基于遗传算法的复合材料结构-声辐射优化研究

研究了外载荷作用下的复合材料结构振动响应和声辐射问题。在此基础上, 分析了复合材料的结构-声辐射优化设计模型, 基于遗传算法进行了对称型复合材料板结构的结构-声辐射铺层几何优化分析。数值算例表明, 复合材料板结构的铺层数、 铺层厚度和铺层角度等参数优化, 可以有效降低结构的振动和声辐射。数值算例结果验证了优化方法的有效性。     

地下工程围岩压力计算的反算法

本文通过有限元与优化理论的结合,提出了一种新的简单的地下工程围岩压力计算的反算法。它以实测位移(或应力)为理论根据,利用优化方法将计算应力(或位移)向实测应力(或位移)逼近,从而反推算出作用在巷道支护上的围岩压力分布。应用了SAP5分析程序和Hooke—jeeves优化方法,对计算地下工程围岩压力分布进行了新的探讨,它将在地下工程设计及地压研究等方面起着重要的参考作用。     

Product and process design effort allocation in concurrent engineering

Concurrent engineering has become a popular approach to product development among manufacturing companies. A lively debate has recently arisen upon whether the technique may be conveniently applied under all circumstances, or whether, in some cases, it may be inferior to other approaches, including the traditional sequential one. The paper proposes an analytical model of concurrent engineering and shows that the main, although not the only, determinants in suggesting the optimal allocation of product and process design effort are the 'evolution speeds' of product and process parameters. Evolution speed indicates whether the major part of design uncertainty is reduced early or late in the design process and, among other factors, is related to the problem's innovative content. It is eventually found that concurrent engineering is optimal in the case of routine design and when the process characteristics are not critical. Under other circumstances other three patterns, termed 'sequential', 'process first' and 'co-operative R&D', appear to be superior.     

基于价值工程的产品优化设计研究

目的 弥补目前价值工程应用到产品优化设计中时,只考虑减少成本,忽视改善质量的局限。方法 运用价值工程的对象选择原则和方法,对预期寿命周期高,已经在市场上销售一段时间的产品进行价值分析,提出初步的设计方向,再通过对某一批次的产品维修记录的统计分析,引入产品功能可靠度的概念,对价值工程提出的设计方向进行修正。结果 将功能可靠度与价值工程的分析相结合,有效弥补传统价值工程指导产品优化设计时,只关注成本而忽视质量的缺点。结论 通过实例进行验证,最终结果表明,功能可靠度与价值工程相结合提出的优化设计方案,在改善产品质量的同时,也有效降低了成本。     

An algorithm for engineering design optimization

In this paper a new concept for development of algorithms for optimal design of engineering systems is presented. The basic idea is to use upper and lower bounds on optimum cost to develop iterative search strategies. The main feature of the concept is that it does not rely on one-dimensional search to compute a step size at any design iteration. Implication of the feature is that the algorithms based on this concept require evaluation of constraint functions only once at any design iteration. This is highly desirable for optimal design of engineering systems because evaluation of functions for such systems is very expensive due to their implicit dependence on design variables. An algorithm based on the new concept is derived in the paper. Several new step sizes are introduced and their relation to proper reduced optimal design problems are presented. A new step size based on the constant cost requirement at some design iterations is introduced. Numerical aspects for the algorithm are also presented. Based on the new algorithm, a general-purpose computer code GRP2 is developed. The code is used to solve several problems to gain experience and insight for the algorithm. Numerical experience with examples is discussed. It is concluded that algorithms based on bounding optimum cost have substantial potential for applications in optimal design of engineering systems.     

USE OF COUNTERPROPAGATION NEURAL NETWORKS TO ENHANCE THE CONCURRENT SUBSPACE OPTIMIZATION STRATEGY

The paper explores the use of artificial neural networks in a concurrent optimization strategy that derives from a decomposition based approach to design of large-scale engineering systems. These problems are characterized by complex couplings that render parametric design methods inappropriate as solution tools. Decomposition methods reduce the large dimensionality problem into a sequence of smaller, more tractable optimization problems, each with a smaller set of design variables and constraints. The decomposed subproblems are rarely decoupled completely, and design changes in one subproblem have a profound influence on changes in another subproblem. Essential components of decomposition based design methods are strategies to identify a topology for problem decomposition, and to develop coordination strategies which account for couplings among the decomposed problems. The paper examines the effectiveness of artificial neural networks as a tool to both account for the coupling, and to develop methods to coordinate the solution in the different subproblems to a converged optimal design     

COMPUTATIONAL ASPECTS OF GEOMETRIC PROGRAMMING 1.INTRODUCTION AND BASIC NOTATION

This paper briefly summarizes the history of geometric programming and shows that efficient computational algorithms are necessary if GP is to retain its place as a major tool for optimal engineering design. Basic notation is established for use by the authors of the succeeding papers in this issue of the journal which is wholly devoted to the algorithmic and computational aspects of geometric programming.     

基于加固效费比的砌体结构抗震加固方案优选方法研究

综合考虑砌体结构层数、既有结构材料强度、震损程度、结构加固抗震能力提升及对应修复加固费用，建立了针对砌体结构的加固效费比模型。以砌体结构加固效费比模型为基础，兼顾施工工期、施工技术、耐久性和对使用功能影响等因素，结合理想点法建立了一套多目标的砌体结构抗震加固方案优选新方法。有针对性地分析了结构层数、既有材料强度、震损程度等因素对加固方案决策影响。结果表明:提出的优选方法能客观地反映既有结构基本信息对方案决策的影响；针对一般砌体加固工程，可结合主观意愿和客观条件，科学、高效地给出优选加固方案，为加固设计实施提供参考依据。     

水下耐压结构拓扑优化设计方法探究

探究了拓扑优化设计方法在水下耐压结构设计中的应用。与固定载荷作用下结构的优化设计相比,此类问题需要正确地确定压力作用面。在拓扑优化过程中,利用变密度法得到的中间结构拓扑实际上可以看成是灰度图。基于此,提出了基于图像分割技术的压力加载面搜索方法,并利用距离正规化水平集方法(DRLSE)检测图像边界。利用数值算例验证了方法的有效性,并研究了静水压力作用下结构的拓扑优化设计问题。在给定材料约束的前提下,研究了不同边界条件下耐压壳体的最小柔顺度及最优结构拓扑形式。优化结果说明了该方法在多球交接耐压壳结构形式优化设计及复杂边界条件下耐压结构新形式探索中的工程应用价值。     

The Four‐Domain Development Diagram: A Guide for Holistic Design of Effective Learning Experiences for the Twenty‐first Century Engineer

The twenty‐first century challenges engineering educators to design learning experiences to strategically and holistically target students' development, including cognitive, psychomotor, social and affective domains. We propose a guide for the design process. The Four‐Domain Development Diagram (4DDD) is a synthesis of learning theory and empirical data. This guide maps the relationships among the major factors that influence learning and presents them in the form of a causal loop diagram, a tool used by systems dynamicists to show how changes in important factors affect other factors within the system. In this paper, we present the theoretical and empirical basis of the 4DDD. We also describe how the 4DDD can be used as a design guide for instructional changes that promote more effective learning experiences for the broader cognitive, social, affective, and psychomotor development required of today's engineering graduate.     

太阳能空调系统设计中人-机-环境关系的优化与分析

传统空调系统的使用需要花费大量的常规能源,由此给能源和环境带来很大压力.解决的途径之一是利用太阳能驱动空调机.随着太阳能应用技术的日益成熟,太阳能空调系统进入小康住宅的比例将会越来越高.然而,太阳能空调的大量使用也会带来一系列人-机-环境关系问题.本文运用人-机-环境系统工程理论,以谋求人、机、环境三大要素最佳综合效益为目标,对系统各要素及其相互关系进行了分析,指出了优化三要素之间关系的方向.