Experimental Assessment of the Thermal Performance of Two Corrugated Metal Roofs

This experimental study is a contribution to the search for solutions to reduce indoor heat gain through sheet metal roofing in hot weather. It has evaluated the thermal impact of two different sheet metal roofs inside of two identical test buildings in sunny weather and cloudy weather conditions. Test building 1 has a single sheet corrugated roof and the building 2 is covered with roof made from top to bottom with corrugated sheet metal, a 12 mm thick serpentine copper tube in which water is circulated, a sheet of aluminium foil acting as a heat reflector, a 4 cm thick polystyrene panel and a 1.5 cm thick plywood. A maximum reduction of 15.1˚C in the temperature of the inner face of the test Building 2 roof was obtained comparatively to the temperature of the inner face of the test Building 1 roof consisting of a single sheet of metal at the warmest hours. In addition, the simple corrugated sheet metal roof of the test building generates high and varied temperatures inside the building. Whereas the proposed heat recovery roof favours low and relatively uniform temperatures inside the building. The proposed sheet metal roof construction technique is very effective in reducing the heat gain through the roof considerably;thus improving the thermal comfort inside sheet metal roofed dwellings. Hot water has been produced by recovering heat from the metal sheet of the roof of test building 2. The temperature of the hot water produced reached of 39˚C. This study could be also an alternative for the reduction of energy consumption due to the use of mechanical means for cooling of sheet metal roofed houses and the reduction of the use of fossil fuels for domestic hot water production.

Enhanced Thermal Performance of Roofing Materials by Integrating Phase Change Materials to Reduce Energy Consumption in Buildings

This work focused on characterizing and improving the thermal behavior of metal sheet roofing.To decrease the heat transfer from the roof into a building,we investigated the efficiency of four types of phase change materials,with different melting points:PCMІ,PCM II,PCM III and PCM IV,when used in conjunction with a sheet metal roof.The exterior metal roofing surface temperature was held constant at 50℃,60℃,70℃and 80℃,using a thermal source(halogen lights)for 360 min to investigate and compare the thermal performance of the metal sheet roofing with and without phase change materials for each condition.The thermal behaviors of the phase change materials were analyzed by differential scanning calorimeter(DSC).The results showed the melting points of PCMІ,PCM II,PCM III and PCM IV were around 45℃,50℃,55℃and 59℃,respectively.The integration of PCM IV into the metal roofing sheet increased the thermal performance by reducing the room temperature up to 2.8%,1.4%,1.0%and 0.7%when compared with the normal metal roof sheet,at the controlled temperatures of 50℃,60℃,70℃and 80℃,respectively.The thermal absorption of the phase change materials also caused a time delay in the model room reaching a steady temperature.The integration of phase change materials with metal roofing sheets resulted in better thermal performance and conservation of electrical energy by reducing the demand for cooling.

Automobile Roof Panel Forming: Prediction and Compensation of Springback and Application of Numerical Simulation Based on Dynaform

The forming of sheet metal in a desired and attractive shape is a process that requires an understanding of materials, mechanics and manufacturing principles. Manufacturing a consistent sheet metal component is challenging due to the nonlinear interactions of various material and process parameters. One of the major issues in the manufacturing of inconsistent?sheet metal?parts is springback. Springback is the elastic strain recovery in the material after the tooling is removed and the final shape of the product depends on the springback amount formed. In this study according to the result of simulation the inverted compensation method is adopted to optimize die surface design. Similarly, to predict and compensate the springback error this study presented an analytical approach of forming process in a stepwise modification of the automobile roof panel. Moreover, based on?Dynaform?and?finite element analysis of sheet metal stamping simulation the sprinback in automobile roof panel is predicted and compensated.?In addition, this study examines the significant requirements of the sheet metal forming precision of automobile body and the simulation of forming, stamping and springback of automobile roof panel is carried out, and the result of simulation also is analyzed.

Wind Loading on a Hyperbolic Paraboloid Free Roof

Wind loading on an H.P. （hyperbolic paraboloid） free roof has been investigated on the basis of a wind tunnel experiment. The roof models of 1 mm thickness were made of nylon resin using laser lithography. The parameters under consideration are the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments were measured by a six-component force balance in a turbulent boundary layer. Based on a combination of the lift and moment coefficients, the design wind force coefficients, CNW^＊ and CNL^＊, on the windward and leeward halves of the roof are proposed. Focus is on the column axial forces induced by wind loading as the load effect for discussing the design wind loads, assuming that the roof is rigid and supported by four comer columns. Indeed, two pairs of CNW^＊ and CNL^＊, generating the maximum tension and compression in the columns, are provided for each of the two or three wind directions parallel to the roof＇s diagonal lines. The proposed values of the wind force coefficients are compared with the specified values in the Australia/New-Zealand Standard for a limited range of rise to span ratio.

Effect of Porosity on the Wind Loads on a Hyperbolic Paraboloid Canopy Roof

A discussion is made of the wind force coefficients for designing the main wind force resisting systems of H.P. （Hyperbolic-Paraboid）-shaped porous canopy roofs on the basis of a wind tunnel experiment. Roof models with a number of small circular holes were made of nylon resin using laser lithography. The porosity was changed from 0 （solid） to 0.4. Besides the porosity, the geometric parameters of the models were the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments acting on a model were measured by a six-component force balance in a turbulent boundary layer. The results indicate that the porosity significantly reduces the wind loads. The design wind force coefficients for porous canopy roofs can be provided by those for solid roofs with the same configuration multiplied by a reduction factor. The proposed wind force coefficients are verified by a comparison of the load effect predicted by the proposed wind force coefficients with the maximum load effect obtained from dynamic analyses using the time history of wind force and moment coefficients. The axial forces induced in the columns supporting the roof are regarded as the load effect for discussing the design wind loads.

Impact of solar reflectivity and infrared emissivity on the thermal performance of metal and concrete roofs in cloudy warmhumid climate

Regions near latitude 0are characterized by warm-humid climate and also by high cloudiness.In these regions,metal roofs has been the most widely used typology.However,in the last decades,the use of heavy concrete roofs has increased significantly.Given its material characteristics,this roof typology offers a higher thermal resistance and thermal mass than a metal roof.Most strategies focus on the use of these characteristics,as well as the use of high reflectivity and emissivity.However,the impact of cloudiness on the effectiveness of these strategies has been little addressed.This research focuses on the impact of reflectivity and emissivity change on the thermal performance of these two roofs in a cloudy warm-humid climate.To achieve this objective,simulations validated with measurements were used.The results show that the efficiency of reflectivity and emissivity is lower in this region compared to other regions.The impact of these properties is further reduced with increasing thermal mass or decreasing thermal transmittance,so the effectiveness of reflectivity and emissivity is minimal on the concrete roof.Finally,this study supports that a metal roof with a reflectivity and emissivity above 0.70 can offer lower daily average temperatures than a concrete roof.

高烈度地区体育馆类公共建筑结构设计探讨

风雨操场作为体育馆类公共建筑,通常造型独特且体型复杂;而作为乙类建筑,存在大跨度、水平和竖向刚度分布不均等结构分析中较难处理的问题,因此其计算分析较为严格,而宁夏银川作为8度区,其抗震要求则更为严格且计算分析亦更为复杂。以银川一中风雨操场为例,对体育馆类结构中存在的问题及其处理方法进行了分析和探讨,为同类建筑的结构设计提供参考。

天窗系统与金属屋面板连接构造设计

对天窗系统与金属屋面板连接构造进行了研究分析与设计。通过对已有天窗连接构造进行分析和总结,基于厦门国际博览中心金属屋面工程提出了一种新的天窗与金属屋面连接构造的设计思路和施工方案,采用了优化后的连接方式和材料,提高了屋面板连接的强度和稳定性,并兼顾了施工的便利性。实际结果表明,提出的天窗连接构造具有较好的受力性能和施工性能,能够满足实际应用要求。

金属屋面系统新型T形连接件抗风性能分析

金属屋面系统对风荷载格外敏感,各屋面构件通过连接件固定,当风荷载较大时容易造成连接失效破坏.根据金属屋面与连接件在风荷载作用下的受力情况及破坏模式,提出一种可自由转动的扣嵌式新型连接件,由连接件的转动来抵消屋面变形及缓解温度应力,使整个屋面系统灵活可变,从而提高整个屋面板的抗风揭性能.通过ANSYS软件建立有限元模型,对新型连接件进行数值模拟分析,获得新型T形连接件的抗风承载力及抗风失效模式,并与原T形连接件进行对比分析,验证新型T形连接件对提高金属屋面系统抗风揭能力的有效性及合理性.

基于随机风作用的直立锁边金属屋面系统损伤评估方法

为提出基于随机风作用的直立锁边金属屋面系统损伤评估方法,选取实际工程案例中某一截面的3块典型区域进行有限元分析,确定屋面系统在最大基本风压作用下的损伤等级。首先确定直立锁边屋面系统性能水准及量化指标,然后采用MATLAB软件模拟脉动风荷载,针对每一块典型区域随机生成了11条风速时程曲线并将其转化为风压荷载。而后在ABAQUS软件中建立典型区域的有限元模型并施加风压荷载,进行非线性动力时程分析,最后进行损伤评估。对比评估结果可知本文提出的损伤评估方法具有较好的合理性,可以用于评估直立锁边金属屋面系统在不同风压荷载作用下的损伤等级。

直立锁边金属屋面系统抗风设计与结构承载力试验

直立锁边金属屋面因抗风揭强度不足常出现风揭破坏。为了详细分析直立锁边金属屋面系统的抗风揭性能,首先,提出了抗风设计关键技术问题。然后,对屋面关键部位的风荷载计算和屋面系统的结构抗力进行研究。最后,对如何选择抗风揭试验方法来获得结构承载力进行对比分析。结果表明,在计算屋面风荷载时,应重点关注局部关键部位,采取规范计算和风洞试验相结合的方法进行验证;在确定直立锁边金属屋面系统结构承载力时,需综合考虑抗风揭静态和动态试验结果。

金属屋面系统交接部位防渗漏及抗风设计研究

金属屋面系统以其轻质、美观及造型多样的特点在大型公共建筑屋面项目中得到了大量应用。本文针对金属屋面系统防水和抗风性能的薄弱点,聚焦金属屋面系统的各交接部位,进行了详细的研究和分析,提出了有效的防渗漏及抗风设计方案和措施,可作为该类屋面系统设计的技术参考。

前期晴天数对不同材质屋面径流污染特征的影响

以城市典型屋面材质(油毡、塑钢、瓦)为研究对象,通过人工模拟降雨考察不同前期晴天数对不同材质屋面径流污染特征的影响。结果表明,不同材质屋面径流中悬浮物(SS)、化学需氧量(COD)、总磷(TP)和总氮(TN)的场次降雨径流平均浓度由大到小都依次为油毡屋面、瓦屋面和塑钢屋面。不同材质屋面径流中重金属的场次降雨径流平均浓度各不相同。总体而言,污染物浓度随前期晴天数增加而增大,主要是小粒径的颗粒物体积分数增加,而大粒径的颗粒物体积分数反而减小。屋面径流中SS是COD、TP和重金属的主要载体,污染物与小粒径的颗粒物相关性更高,因此要想控制屋面径流中的COD、TP和重金属,关键是控制细小的颗粒物。

直立锁边金属屋面抗风揭及防渗漏施工技术研究

金属屋面在使用的过程中一直面临着防风揭和防渗漏的关键技术问题。为了解决这些问题,以厦门国际博览中心会议中心项目中的金属屋面工程设计施工为背景,系统介绍了金属屋面防风揭和防渗漏的施工创新技术,有效增强金属屋面的抗风揭和防渗漏性能,以提高直立锁边金属屋面结构使用寿命和耐久性。

大型国际航站楼异形双曲金属屋面系统施工研究

以杭州萧山国际机场三期项目新建T4航站楼为例,研究了超大面积异形双曲钢结构金属屋面系统、不锈钢天沟系统、天窗系统、不锈钢防坠落系统和防雷系统施工工艺及施工关键技术,提炼总结形成超大面积异形双曲金属屋面施工成套技术,实现了各系统的精准安装,为后续大型会议会展场馆和机场类超大型建筑金属屋面施工提供可借鉴经验。

360°咬合金属板屋面风致易损性分析

360°咬合金属板屋面作为众多形式金属屋面中的一种,具有良好的抗压能力,然而在真实风环境下,该类屋面的抗风揭能力尚有待研究。针对360°咬合金属板屋面系统的风灾易损程度开展了量化分析研究,以判定其真实抗风能力。为此,研究结合了力学试验与数值仿真等技术手段,对某TB开关站厂房的360°咬合金属板屋面系统的承载力以及风荷载效应进行分析。基于概率学知识,提出连接件失效概率的高效计算方法,进而快速分析金属板单元失效概率以及屋面整体的易损性,并提供损失的平均水准及变异程度量化结果。研究发现,荷载最不利工况通常对应来流垂直于屋脊线时,此时该类屋面在风力达到9级时出现破坏的迹象,当风力达到12级时,整个屋面极有可能被整体掀飞。

台风工况下施工过程各阶段金属屋面抗风揭技术

作为建筑物重要的维护结构之一,金属屋面在台风等极端自然天气条件下的抗风性能尤为关键。因此,针对台风工况下施工过程中各阶段金属屋面的抗风揭技术进行了研究分析,提出了一系列有效的技术方案和加固措施,以提高金属屋面在台风工况下的抗风性能和安全性能,减少台风造成的损失和风险,为保护人民生命财产安全和促进可持续发展做出积极的贡献。

钢筋混凝土仿古建筑双曲屋面施工工艺研究

探讨在钢筋混凝土仿古建筑双曲屋面施工的工艺和技术要点,以及在“盘扣-木模”支撑体系下实现复杂结构的施工过程。以某项目斋堂综合楼屋面为例,介绍大跨度组合曲面结构的施工难点,包括曲面造型、高低跨屋面和大跨度预应力曲屋面。通过对深化BIM模型、模板支撑架定位、曲面模板拼装、钢筋绑扎、混凝土浇筑以及过程控制及养护等关键工艺的突破,成功实现在“盘扣-木模”支撑体系下的双曲屋面施工。总结高低跨屋面施工的关键工序和大跨度预应力曲屋面的特殊处理方法,以期为类似工程提供经验。

14煤层开采铺设金属网人工假顶可行性分析

胜利煤矿一采区规划开采的煤层为14煤层和近距离下伏的15煤层,为确保在采15煤层的开采安全,提出在开采14煤层时工作面顶板铺设金属网形成人工假顶,对14煤开采后的人工假顶进行可靠性分析,采用简支梁稳定分析法,确定人工假顶极限状态的厚度为5.74 m。根据水化学实验可得,采空区积水对铺设金属网有腐蚀性,分析采空区铺设的金属网有效赋存时间不超过3 a。结合再生顶板形成时间分析确定,当15煤层与14煤层存在1 m以上的层间距时,15煤至少需要在14煤层开采完毕3.5 a后进行采掘活动;当15煤层与14煤层合层时,15煤至少需要在14煤层开采完毕5 a后进行采掘活动。

耀雪冰雪世界项目施工难题及关键技术研究

以上海耀雪冰雪世界大型室内滑雪场项目为例,为保证质量、安全及建筑功能的实现,阐述了在整个项目施工过程中的难特点,并针对难题提出针对性的研究方向和对策,为类似冰雪场馆设施的建设提供了有价值的参考经验。