Influence of the design constraints on the thickness optimization of glass panes to achieve lightweight insulating glass units in cruise ships

The increasing complexity and size in cruise ships demands for lightweight structures and practical but accurate design methods. Conventionally, the focus has been on the steel parts of the ship, as they make most of its weight. However, the proportions of other materials are increasing. Therefore, this study attempts to provide better understanding how one could reach the lightweight designs of insulating glass units (IGUs) in ships. These are windows where at least two glass panes are separated by a hermetically sealed cavity. They are thin-walled structures that benefit not only from the geometrically nonlinear behavior, but also from the load sharing. Considering these effects, their behavior is studied using the nonlinear Finite Element Method and Particle Swarm Optimization. Different design criteria are imposed on the thickness determination of the glass panes with different shapes. Rectangular, triangular, and circular shapes are considered. The results show that the triangular shapes have the least weight for a given area when the deflection criterion is the dominating one. When maximum principal stress is the thickness defining criterion, the shapes perform almost equally well. The ratio between the pane thicknesses had the most influence on the behavior of the IGU. As it increases, i.e., one pane is significantly thicker than the other, the load sharing percentage drops, but it provides the most lightweight solution. Closer it is to 1, more equally the structural stresses are divided between the panes, i.e., redundancy is achieved. Finally, it is possible to establish a simple but effective method for the thickness determination of these IGUs using the results of this study. However, more work is required, including numerical analysis and experimental testing.     

Design optimization of a TetraSpar-type floater and tower for the IEA Wind 15 MW reference wind turbine

We present an optimization study for the conceptual design of wind turbine floaters of the TetraSpar type. The optimization variables include all geometric dimensions of the floater, keel, mooring lines and tower design. A gradient based optimization method is applied to a mass proportional objective cost function. The objective function accounts for the different weight components of the floater, including secondary steel, the wind turbine tower, and the mooring system. A frequency domain response method is utilized, so that each design evaluation also takes into account the dynamic response for 12 wind speeds with associated wave conditions. Nineteen constraints are applied for static and dynamic response, natural frequencies, and fatigue at the bottom of the tower. Two reference designs are presented, namely one with a soft–stiff tower and one with a stiff–stiff tower. Due to the anti-phase coupling of the floater pitch and tower vibration, the soft–stiff tower needs a stronger floater stiffness in pitch. This design thus has a larger water plane area moment than the more compact stiff–stiff floater, which is found to be the least economical. A constraint analysis is next presented based on Lagrange multipliers and a relative cost index. We find that the strongest cost influence is exerted by the 3P tower frequency constraint for the stiff-stiff and soft-stiff designs. Finally, a third design variant with a free optimizable tower frequency is introduced. This design is found to be 11% cheaper than the soft–stiff design and highlights the potential cost savings of tower designs within the 3P region.     

龙溪口航电枢纽仿自然鱼道设计

为确定岷江航电龙溪口枢纽仿自然鱼道布置的合理性和设计基本参数,对工程河段开展鱼类资源调查和游泳能力测试。通过三维数值模拟计算验证鱼道池室尺寸与池室内流速关系,通过物理模型试验对鱼道内部水流流态、控制断面流速等水力学参数进行研究。提出仿自然鱼道设计方案：1)鱼道进口布置在发电厂房尾水渠末端,采用发电尾水诱鱼并在进口布设补水设施;2)鱼道采用藕节形+梯形断面结构,内设横隔,鱼道和横隔均采用天然卵石堆砌;3)下游河道左岸布设缓流平台,消除鱼类上溯流速屏障。试验结果表明,龙溪口仿自然鱼道池室内部流态多样性,流速满足过鱼要求。     

龙溪口航电枢纽工程鱼道进口布置论证与优化*

为确定龙溪口航电枢纽左岸仿生态鱼道的进鱼口布置方案,结合枢纽的运行工况和现有地形条件,发现较多工况下鱼道进口附近水流条件不满足鱼类上溯要求,需采取一定的工程优化措施。针对龙溪口枢纽的特点,选取典型工况对进鱼口及枢纽下游的水流条件进行研究。根据二维数值仿真模型的研究成果,拟采用拆除电站与泄水闸之间部分纵向围堰、电站尾水坎下游开挖疏浚以及左岸生境重构等方式,优化鱼道进口水流条件。对比分析不同进鱼口布置方案的优劣,推荐采用生境重构结合开挖疏浚的综合措施,优化龙溪口鱼道进口及下游流场,两者均满足龙溪口鱼道进口的流速要求。相关成果可为类似进口水流条件的数值模拟及进鱼口布置提供技术参考。     

海洋平台火炬塔筒体结构应力分析

针对海洋平台火炬塔筒体结构强度设计问题,采用Ansys软件的静力学模块对单个火炬塔筒体和3个火炬塔筒体进行静力分析,得到不同工况条件下的结构应力值和变形位移值。结果表明,单个火炬塔筒体可承受的最大压力载荷大于3个火炬塔筒体可承受的最大压力载荷。火炬塔筒体的分析方法和结果对后续石油化工废气处理装置的设计和安装具有一定的指导意义。     

基于轨道极限状态法的过渡板受力分析和配筋设计研究

京张高铁官厅水库特大桥为简支拱型大跨度钢桁梁桥,为防止梁端转角或错台量过大,降低梁端扣件系统受力,梁缝处设计采用了过渡板结构。为保证过渡板设计合理性和安全性,建立过渡板有限元实体模型进行受力分析,并首次运用轨道极限状态法对过渡板结构进行配筋设计。分析表明:(1)温度梯度作用对过渡板(420 mm厚)受力影响较大,在设计荷载中占据主导因素,在正温度梯度下,过渡板底部弯矩达到124.155 kN·m/m;(2)过渡板底部纵向弯矩在荷载基本组合作用下达到最大值,且实配配筋率最大,配筋时应注意以裂缝宽度为控制指标进行设计。     

BIM技术在铁路预应力混凝土连续梁零号节段深化设计中的应用

近年来,部分铁路预应力混凝土连续梁支座附近出现浇筑不密实、蜂窝麻面等问题,一定程度上影响了连续梁质量。针对这一现状,结合BIM及C#语言技术,从深化设计平台的选择、精细化模型的构建以及BIM技术在深化设计中的应用开展研究。结果表明:(1)通过合理拆分并在空间上进行布尔组合,能够较快构建铁路连续梁零号节段BIM模型,满足深化设计条件;(2)基于BIM模型开展深化设计、生成2D图纸并统计工程数量,能够直观发现设计中的不足,一定程度上提升设计质量和效率。     

高速铁路正交异性板钢桁梁整体计算模式及方法研究

随着我国高速铁路的快速发展,正交异性板钢桁梁桥得到了广泛的应用,国内外的学者也对正交异性板钢桥作过一些试验和计算分析研究,但是没有形成一套可供系统应用的计算模式及方法。结合实际工程经验,总结正交异性板钢桥面系类型及其适用范围,分析正交异性板三体系受力机理,归纳整理了4种正交异性板计算方法并分析各自优缺点,给出桥面系杆件上翼缘板有效宽度计算公式、桥面系纵向参与系数计算方法,以及在平面模型中下弦杆弯矩的计算方法。通过对正交异性整体钢桥面结构形式、受力特性和整体设计计算方法等进行较为系统的分析研究,总结出一套完善的正交异性板钢桁梁设计方法,并成功应用于多座钢桥的设计中,该方法可为类似桥梁的设计提供理论参考。     

城际铁路公交化运营客服系统研究

我国城市群的建设在快速推进中,区域协调发展需要交通支持,京津冀城市群是其中的重要发展区域,提出了"交通先行"的发展理念。轨道交通是区域交通的骨干方式,在多层次轨道交通系统中,城际铁路是服务于城市群内公共交通出行的重要交通方式,目前国内运营的城际铁路主要采用传统大铁制式,从运输组织到运营方式都与干线铁路类似。但在这种模式下,由于受到运营理念及管理制度等体制限制,以及信号系统、售检票系统等硬件限制,运输组织以及车站乘客组织等难以满足城市间大量乘客频繁出行的需求,需要采用公交化运营以符合这种高频率人物交换的发展趋势。因此,结合城市轨道交通公交化运营方法,并考虑城际铁路运营的特点需求,通过对运输组织模式、售检票系统、站台候车组织模式、动车组及站台门系统进行研究,形成城际铁路公交化运营客服系统。     

基于CBR的山区铁路桥梁大高差桥墩设计研究

针对山区铁路桥梁普遍具有的大高差桥墩这一显著结构特征,引入基于案例推理技术,力争把丰富的山区铁路桥梁大高差桥墩设计经验积累起来,并为后续的山区铁路桥梁建设提供设计参考,使设计更加高效与合理。首先建立包含梁桥、刚构桥、刚构-连续组合体系桥等桥型在内的山区铁路桥梁案例库,采用熵权法确定桥梁主要特征属性权重,并通过灰色关联分析检索得到相似案例的解决办法,最后将该解决办法进行修正以适配目标案例。实例应用结果表明:该技术可对山区铁路桥梁大高差桥墩设计提供合理有效的建议。