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.     

大跨度机库钢桁架中的预应力钢绞线穿束施工技术

以成都天府国际机场国航基地工程(机务维修一期)101号维修机库大跨度边桁架中的预应力钢绞线施工为背景,针对预应力钢绞线超长、单束钢绞线数量多、钢绞线穿束时质量大、摩擦力大等难点,提出钢绞线设计分束优化、增加增强隔板、研发穿束牵引装置等方案,通过实施该方案,减小了穿管时的牵引力,大大降低了钢绞线穿管损伤风险,同时大幅节省了穿管措施费用。     

供热站主厂房工艺布置和结构分析

由于工艺布置和建筑造型的需要,供热站主厂房设计变得相当复杂与繁琐,文中通过工程实例对其进行分析,表明工艺之间相互配合、在充分利用平面和竖向空间基础上、能够达到工艺顺畅和结构抗震性能良好的统一。     

大跨径网架屋顶设计与施工实践

某物资仓库拟采用框架结构和40 m跨网架屋顶。首先根据规范确定了屋顶荷载，并根据该建筑物位于台风区的实际，着重研究了风荷载的取值情况。该网架采用螺栓球节点，形式为正放四角锥形，施工采用分段整体吊装和高空散装的安装方式。实际使用情况表明，该物资库采用网架结构可靠耐用，且缩短了施工工期，取得了较好的经济效益。     

预应力索桁架点支式玻璃幕墙技术

预应力索桁架点支式玻璃幕墙是目前最先进的一种新型幕墙结构,改变了传统建筑的表现形式,通过建筑内外空间结构的有效融合,集建筑、功能、美观、实用等于一体,提高整体承载力,加大空间结构,造型美观富有时代感和生命力。