Evolutionary Algorithm Integrating Stress Heuristics for Truss Optimization

The optimal truss design using problem-oriented evolutionary algorithm is presented in the paper. The minimum weight structures subjected to stress and displacement constraints are searched. The discrete design variables are areas of members, selected from catalogues of available sections. The integration of the problem specific knowledge into the optimization procedure is proposed. The heuristic rules based on the concept of fully stressed design are introduced through special genetic operators, which use the information concerning the stress distribution of structural members. Moreover, approximated solutions obtained by deterministic, sequential discrete optimization methods are inserted into the initial population. The obtained hybrid evolutionary algorithm is specialized for truss design. Benchmark problems are calculated in numerical examples. The knowledge about the problem integrated into the evolutionary algorithm can enhance considerably the effectiveness of the approach and improve significantly the convergence rate and the quality of the results. The advantages and drawbacks of the proposed method are discussed.     

Object-Oriented Optimization Approach Using Genetic Algorithms for Lattice Towers

A new approach is presented for the optimization of steel lattice towers by combining genetic algorithms and an object-oriented approach. The purpose of this approach is to eliminate the difficulties in the handling of large size problems such as lattice towers. Improved search and rapid convergence are obtained by considering the lattice tower as a set of small objects and combining these objects into a system. This is possible with serial cantilever structures such as lattice towers. A tower consists of panel objects, which can be classified as separate objects, as they possess an independent property as well as inherent properties. This can considerably reduce the design space of the problem and enhance the result. An optimization approach for the steel lattice tower problem using objects and genetic algorithms is presented here. The paper also describes the algorithm with practical design considerations used for this approach. To demonstrate the approach, a typical tower configuration with practical constraints has been considered for discrete optimization with the new approach and compared with the results of a normal approach in which the full tower is considered.     

长距离伪斜机头旋转开采技术研究

针对负伪斜状态下综采工作面机头旋转开采过程中存在的问题，通过对工作面1号支架进行精确定位安装、采取合理的调斜和进刀方式等技术工艺，解决了负伪斜旋转开采过程中工作面支架和输送机容易下窜的技术难题。该技术的成功应用，提高了工作面的采出率，为综采工作面旋转机头开采提供了技术参考。     

基于三角形试验的引张线卡阻位置定位分析

引张线广泛应用于大坝水平位移监测,但在长期运行过程中会因线体卡阻而影响观测成果的真实性。因引张线的护管为不透明的PVC管或镀锌管,直接观察引张线卡阻部位存在一定难度,更换整根护管也显得不经济。为经济有效地消除卡阻,介绍运用三角形试验来准确判定卡阻位置的方法,并给出了相关计算公式。工程实例验证表明,该方法可准确找到卡阻位置,为以后引张线卡阻问题处理提供了参考。     

A Two-Stage Method for an Approximate Calculation of Statically Indeterminate Trusses

The paper presents the principles of a method, which in two simple stages makes possible to carry out the statically calculation of values of forces acting in the fiat static indeterminate trusses. In each stage, it is considered the static determinate truss, scheme of which is obtained after remove the suitable number of members from the basic static indeterminate truss. The both intermediate statically determinate trusses are of the same clear span and they are loaded by forces of half values applied to the corresponding truss nodes. The method applies one of the typical procedures of calculation of the statically determinate trusses and then it is applied in an appropriate way the rule of superposition for obtaining the final values of forces acting in particular members of the basic truss. The values of forces calculated in this way are of a very close approximation to the force values determined in the special and complex ways being considered as the exact calculation methods. The proposed method can be useful mostly but not only for the initial structural design of such systems. The simplicity of the two-stage method justifies an assumption that it can be relatively easy and worthy to adjust to the requirements of the computer aided technology of statically calculation of the complex forms of trusses.     

马道静载试验与有限元分析

本文以某大剧院多功能厅钢桁架结构马道为背景,对该马道进行了静载试验研究。由于是新建结构,对其正常使用存在不确定性,所以用单调加载静力试验来研究其承载力和稳定性。通过静载试验得到马道最大跨主要受力杆件的应变大小以及最大跨挠度大小等重要数据,然后使用有限元软件ABAQUS进行了建模分析,由此也进一步的验证出检测数据的可靠性。有了这一分析过程也将为现实工程结构静载试验检测鉴定提供参考。     

天津津门酒店结构设计

天津津门酒店为地上17层的连体结构。从地上层14开始两个框剪结构单体连为一体,连体部分采用了钢桁架,桁架上下弦杆分别伸入各单体的剪力墙内一跨,连体部分的跨度为30～35m。介绍了天津津门酒店的结构体系、地基基础等设计要点的同时,重点介绍了该连体结构设计的主要问题和解决方法。通过弹塑性时程分析找出了工程的结构薄弱部位,同时也验证了结构体系是合理的。     

An approach of topology optimization of multi-rigid-body mechanism

Topology synthesis of multi-rigid-body mechanisms has always been a very important stage in the mechanism design process. In most cases, the topology of the multi-rigid-body mechanism for particular task is obtained by designers’ experience and ingenuity, rather than automatic approach. In this work, an approach of topology optimization of multi-rigid-body mechanisms is investigated. The core process of the approach is an automatic optimization design process. In this approach, we construct kinematics mapping from truss structures to the joint-linked mechanisms, which transforms the topology optimization problem of multi-body system into the truss structure optimization problem. We also develop a new strategy for topology optimization of statically determinate truss, the advantage of which lies in the ability dealing with statically determinate truss topology optimization problem compared to the existing methods. By automatically optimizing the topology of the truss structure, the topology of the multi-rigid-body mechanism is optimized automatically, accordingly. Here, we utilize the investigated approach to design suitable layout for multi-rigid-body micro-displacement amplifying mechanisms (MMAMs) with a large amplification ratio (>50). The layout consists of not only the topology information of the mechanism, but also the dimension parameters of the mechanism. The procedure of the approach is carried out in steps, and a human–computer interaction program has been developed for it. Using the developed program, different MMAMs are achieved. Meanwhile, the direct kinematics analysis of the MMAMs is achieved automatically, the existence of dead point position in the mechanism within movement range is checked and the micro-displacement amplification ratio is calculated out. The computing results are validated by the ADAMS^® motion simulation, which proves that the achieved MMAMs fully fulfill the functional requirement. Along with two of the achieved MMAMs, the approach is explained, its functionality is shown, its advantages, limitations, some open problems and future works are discussed.     

Cyclical parthenogenesis algorithm for layout optimization of truss structures with frequency constraints

Structural optimization with frequency constraints is seen as a challenging problem because it is associated with highly nonlinear, discontinuous and non-convex search spaces consisting of several local optima. Therefore, competent optimization algorithms are essential for addressing these problems. In this article, a newly developed metaheuristic method called the cyclical parthenogenesis algorithm (CPA) is used for layout optimization of truss structures subjected to frequency constraints. CPA is a nature-inspired, population-based metaheuristic algorithm, which imitates the reproductive and social behaviour of some animal species such as aphids, which alternate between sexual and asexual reproduction. The efficiency of the CPA is validated using four numerical examples.     

桁架因高度不同而内力变化的优化设计

通过马钢股份公司三钢轧总厂全连铸工程46m长钢桁架的设计,按照桁架高度5m和6m的两种方案,分别计算出桁架因高度不同而内力变化的各项设计指标,从而选出优化设计方案.