重庆国际博览中心铝合金屋面设计

铝合金网壳结构已经在一些工程项目中得到应用,但类似于重庆国际博览中心项目的铝合金屋面框架、桁架结构体系仍应用较少。重庆国际博览中心项目铝合金屋面跨越下部多个钢结构单体,面积大、建筑外型复杂,通过受力分析提出了结构优化方案。通过合理设置结构缝和温度缝,将大型屋面分成多个独立区域,各区域采用框架或桁架结构形式,使得结构受力简单,并降低温度效应。介绍了铝框架及铝桁架采用的节点形式,为其他类似大型屋面项目提供参考。     

膜下索穹顶太阳辐射非均匀温度效应研究

索穹顶结构常采用膜屋面,高透光膜屋面可使太阳辐射透过膜材作用在下部结构上,且降低了结构周围的对流换热作用,可能形成"温箱效应",使膜下索穹顶结构产生显著的非均匀温度效应。基于内蒙古伊旗全民健身中心索穹顶,分别考虑ETFE、PTFE两种膜材,对其进行膜下索穹顶结构太阳辐射非均匀温度场和温度效应分析。结果表明:膜下索穹顶结构存在显著的太阳辐射非均匀温度场和温度效应,膜材的太阳辐射透射系数是主要影响因素之一。升温导致索穹顶结构预应力损失严重,考虑太阳辐射非均匀升温工况比考虑极端气温均匀升温工况的膜下索穹顶预应力损失更为明显,在设计中应予以考虑。     

钢筋混凝土结构温度、收缩作用和效应分析

结合已有的研究成果对钢筋混凝土结构的温度、收缩作用和效应进行了初步探讨，分析了框架结构屋面梁和楼面粱板温度、收缩应力，并提出有关控制楼板裂缝的建议。     

长葛体育馆结构设计与分析

长葛体育馆主体结构为平面不规则的超长结构,看台为阶梯形布置,没有明显的结构层,屋面为空间正交平面桁架体系。不规则结构一般会产生较大的扭转效应,超长结构内力和变形受温度作用效应的影响不能忽视。综合考虑了各种复杂因素,对结构设计提出了具体的分析方法。对结构体系进行了整体和局部分析,提出了温度作用的计算方法和构造措施。     

双坡轻钢结构门式刚架的内力计算

目前,轻钢结构厂房最常见的结构形式为双坡门式刚架。轻钢结构门式刚架自重较轻,受屋面活荷载的影响较大,在内力计算时通常由屋面活荷载所控制。屋面活荷载包括不上人屋面活荷载(即屋面施工及检修荷载)和屋面雪荷载,有时还会有屋面积灰荷载。通过分析荷载规范对不上人屋面活荷载和屋面雪荷载的相关规定,提出了一种双坡轻钢结构门式刚架的内力计算方法,即兼顾屋面雪荷载全跨均匀布置的效应和不上人屋面活荷载全跨不均匀布置的效应,取其最不利效应进行构件截面设计的方法。     

空间结构太阳辐射非均匀温度问题的研究进展

对于有大型室外构件或大面积透光性屋面的大跨钢结构,在时变太阳强烈辐射作用下,结构经历的温度效应实质是在辐射-热-流多物理场耦合作用下的非均匀时变温度效应,往往会在结构中引起较大的温度变形和温度应力,成为结构的控制荷载之一。从钢材表面太阳辐射吸收系数、太阳辐射下钢结构温度实测以及数值模拟方法、典型结构形式和工程的太阳辐射非均匀温度效应研究等方面,总结和分析了空间结构太阳辐射非均匀温度问题的研究进展,提出低吸收高反射的新型涂料研发、结构太阳辐射非均匀温度作用简化模型、地基-基础-混凝土结构-钢结构协同太阳辐射非均匀温度效应的精细化研究等3项亟待解决的关键课题,为进一步研究空间结构太阳辐射非均匀温度效应提供了一定的思路和参考。     

屋面生态节能板温度效应研究

以屋面生态节能板为研究对象,通过模拟试验,将播种密度和保水剂用量分别设计了3个处理组合,采用两因素交叉分组,加上对照组共10个处理组合,比较分析屋面生态节能板屋面内表面温度变化特征,研究了播种密度和保水剂用量对屋面生态节能板节能效应的影响。结果表明:屋面生态节能板温度效应的季节性差异明显,在夏季屋面生态节能板具有较好隔热效果,播种密度和保水剂用量对隔热效应有显著影响;在冬季屋面生态节能板体现出良好的保温作用,但播种密度和保水剂用量对保温效应影响不明显。     

加气混凝土屋面前景广阔

在由北京建材集团主办的中国国际加气混凝土应用研讨会上,与会专家们认为:加气混凝土防水隔热叠合屋面是我国今后建筑设计和施工应用的发展方向。随着我国混凝土结构和预应力混凝土结构的发展,平屋面在各类型建筑上得到了广泛的应用,其防水施工技术以刚性防水屋面为主,但往往因防水层表面受温度效应引起的热胀冷缩及材料本身干缩干裂导致屋面渗漏,以及结构变形将防水层拉裂或由于建筑构造不尽合理,或施工粗制滥造而漏水。因此,从材料和结构上探索新的设计方案,是建筑屋面防水的一项重要课题。     

2010年上海世博会马来西亚馆结构分析与设计

2010年上海世博会马来西亚馆的屋盖造型新颖独特,其结构设计的关键问题在于如何进行结构选型及如何保证屋面结构面内刚度。借鉴传统马来西亚建筑结构形式,对三种结构方案进行分析比较,选择了传力路径明确且便于施工的结构方案;提出在屋面薄钢板屈曲后,以不考虑塑性板带刚度的方式来近似量化屋面板蒙皮效应,通过折减屋面钢板平面刚度使蒙皮效应直接在整体计算模型中体现;最后介绍了为适应屋盖造型和保证屋面刚度,工程主要节点的构造分析与处理等。结构选型的思路及量化薄板蒙皮效应的方法可供类似结构分析时参考。     

天狮大学城市体育场结构设计

天狮大学城市体育场地下室为整体,地上混凝土结构通过5道永久结构缝分成5个独立单元,屋面钢结构南北向380m长不设缝,5个独立单元通过屋面钢结构形成连体结构。屋面钢结构采用单层网壳体系,其中体育馆上空局部为双向正交桁架。详细介绍了结构体系和项目特点;针对超长混凝土结构进行了温度应力分析;详细介绍了结构抗震性能化设计过程;通过多点多维时程分析,研究了行波效应对超长钢结构及周边混凝土竖向构件的影响;通过大震动力弹塑性时程分析,研究了结构的动力特性和抗震性能。结果表明,结构满足抗震性能化设计目标。     

Timber flat roofs: effects of thermal and moisture changes

In describing continuing research in the UK into the behaviour of flat roofs and the actual climates in roof spaces, this article also summarises accumulated knowledge about the effects of temperature and moisture changes on timber products such as plywood and chipboard. At seminars in Britain during the past year, the studies of roof void climates at the Scottish Laboratory have been described by Dr Philip Cornish, and the PRL work on the effect of temperature and moisture changes on timber has been recounted by Dr John Dinwoodie.     

Modeling the heat diffusion process in the abiotic layers of green roofs

Green roofs have been increasingly installed to alleviate some common environmental problems. The thermal benefit of living vegetation on rooftop has been extensively studied. The individual and joint contribution of the non-living green roof layers, namely soil, rockwool (water storage) and plastic drainage layers, to thermal performance of green roof has seldom been assessed. This study evaluates the insulating and cooling effects of these abiotic materials. A one-dimensional theoretical model was developed to assess the heat diffusion process in the layers. The model was validated with empirical results from three experimental plots. A calibration procedure was successfully applied to determine key model parameters. The model can capture the most critical features of temperature variations and thermal performance of common abiotic green roof materials. The appreciable water-retention capacity of rockwool plays the dual role of supplying water to the soil to enhance evaporative cooling, and increasing the specific heat capacity of the green roof. The plastic drainage sheet with ample air spaces serves as an excellent thermal insulator. The model remains robust despite seasonal and weather variabilities. Our research findings contradict with some researches in the temperate region that the thermal dissipation in green roofs with dense vegetation is lower than thermally insulated bare roofs. The theoretical model could be used to simulate the micro-environmental conditions and predict the thermal performance of different materials to improve green roof design.     

A new thermal performance index for dwelling roofs in the warm humid tropics

This research aims to find a scientific rating scheme for roof system for the warm humid tropics. The overall air-to-air thermal transmittance (U-value) or thermal resistance (R-value) of roof are most widely used properties, but these are based on steady-state heat conduction and do not respond to changing conditions of climate, design and comfort needs. The paper presents a new thermal performance index, which is based on thermal comfort and actual thermal performance of a roof design option. It provides a basis for identifying the optimum roof design for unconditioned and acclimatised regimes. A review of the acceptable limits of ceiling surface temperature is presented. The mathematical modelling for predicting performance of roof based on admittance procedure and derivation of thermal performance index is described. In the proposed scheme the galvanized iron roof is given 0% rating and the roof satisfying the comfort needs for the given climate is rated as 100%. Illustrative examples of built roofs or design options are taken from India and Australia. It clearly shows that the roofs with the highest thermal resistance are not necessarily optimum solutions.     

Wind force coefficients for designing free-standing canopy roofs

Wind loads on free-standing canopy roofs have been studied experimentally. Three types of roof geometries, i.e. gable, troughed and mono-sloped roofs were tested. Wind pressures were measured simultaneously at many points both on the top and bottom surfaces of the roof model for various wind directions. Based on the results for the most critical positive and negative peak pressure coefficients irrespective of wind direction, the wind force coefficients for the design of cladding and its immediately supporting structures are proposed. Correlation between the wind force and moment coefficients is investigated, and appropriate wind force coefficients for the design of main wind force resisting systems are proposed. Axial forces in the columns supporting the roof are regarded as the most important load effect. Two loading patterns causing maximum tension and compression of columns are considered.     

大尺度高低跨柱面屋盖的风压系数分区研究

针对大尺度高低跨柱面屋盖体系风压分布变化梯度较大、跨间相互干扰以及此类屋盖风压分区无相关规范可查阅等问题,在得到各种风向下最不利极值风压的基础上,采用K-means聚类的风压系数快速分区方法将高低跨柱面屋盖表面划分为多个区域,并计算了各区域的分区风压系数。同时,在高低跨柱面屋盖风压系数分区研究过程中,对K-means方法的k值取值范围和最佳k值确定方法进行针对性改进。结果表明,高低跨柱面屋盖的边缘属于风敏感部位,而中间部分风压变化较小,因而在进行大尺度平屋盖抗风设计时,采用聚类方法进行风压分区更为合理。     

Biophysical properties and thermal performance of an intensive green roof

Green roofs have been increasingly enlisted to alleviate urban environmental problems associated with urban heat island effect and stormwater quantity and quality. Most studies focus on extensive green roofs, with inadequate assessment of the complex intensive type, subtropical region, and thermal insulation effect. This study examines the physical properties, biological processes, and thermal insulation performance of an intensive green roof through four seasons. An experimental woodland installed on a Hong Kong building rooftop was equipped with environmental sensors to monitor microclimatic and soil parameters. The excellent thermal performance of the intensive green roof is verified. Even though our site has a 100 cm thick soil to support tree growth, we found that a thin soil layer of 10 cm is sufficient to reduce heat penetration into building. Seasonal weather variations notably control transpiration and associated cooling effect. The tree canopy reduces solar radiation reaching the soil surface, but the trapped air increases air temperature near the soil surface. The substrate operates an effective heat sink to dampen temperature fluctuations. In winter, the subtropical green roof triggers notable heat loss from the substrate into the ambient air, and draws heat upwards from warmer indoor air to increase energy consumption to warm indoor air. This finding deviates from temperate latitude studies. The results offer hints to optimize the design and thermal performance of intensive green roofs.     

温度监测系统的设计及在屋顶绿化节能效果检测中的应用

为了监测屋顶绿化的节能效果,设计并实现了屋顶绿化温度监测系统。该系统可以实现现场数据的实时采集,并且采用无线数据传输模块,可以对屋顶绿化的热工性能远程监测,通过该系统可以得到种植不同植物屋顶的热工参数。采用多项式最小二乘法对温度传感器的模拟量信号与温度值间的关系进行拟合,提高了系统的采样精度。     

自然状态草地式屋顶绿化隔热特性分析

在夏季自然通风状态下对重庆有绿化屋顶和无绿化屋顶内表面温度和气候参数进行了测量。通过对测量数据的统计分析,得到以下结论:屋顶绿化对降低屋顶内表面最高温度的效果非常显著,降低平均温度效果稍差,热天气有绿化屋顶内表面对空气的总平均增温量为无绿化屋顶的1/4左右;以天为周期,有绿化屋顶内表面对空气的增温量与太阳辐射照度的变化有较强的反向性,以一段晴雨天气为周期,这种反向性减弱,而以整个夏季的热天气为周期,这种反向性转变为很强的正向性;对于无绿化屋顶,无论热作用周期的长短,内表面对空气的增温量与太阳辐射照度的变化都呈现很强的正向性。     

城市设计视角下建筑顶部形态的设计控制研究

在不断发展的建筑技术、建筑材料科学的推动下,现代建筑顶部在设计功能和空间利用方式上都有了较大的进展;伴随着人类审美观念的演进和建筑设计思潮的变迁,当代建筑的顶部设计已经开始越来越多地向特色化和区域整体化的方向发展。在对建筑顶部演进历程和设计理论进行研究的基础上,对天津滨海新区响螺湾CBD项目的建筑物顶部设计过程进行了系统地介绍和分析,在总结其设计理念和形态特征的同时,详细介绍了该项目建筑顶部设计的具体流程和技术要素。     

杭州奥体博览城网球中心结构设计研究综述

杭州奥体博览城网球中心的屋盖为开合屋盖,下部看台及功能用房采用钢筋混凝土框架-剪力墙结构,上覆的钢结构屋盖由固定屋盖和可移动屋盖组成,固定屋盖由24个花瓣形悬挑主桁架旋转复制组成,可移动屋盖由8片可旋转花瓣形网壳组成。固定屋盖上方设置的8片大悬挑移动屋盖,采用平面旋转45°的开启方式,8片花瓣闭合时覆盖整个场地。基于工程结构体系以及全过程结构设计,对于超长混凝土结构温度收缩效应计算方法、移动屋盖在移动过程中的多模型多工况设计、看台外倾引起的重力荷载作用下看台斜梁和顶部环梁受拉的处理、施工后浇带的合拢时间对于整体结构的受力的影响以及大跨度钢结构的屈曲稳定等问题进行专项分析和处理,可为类似工程结构设计提供参考。