课件：第章膜结构.ppt

Membrane Structure,Chapter 6 第六章,Membrane Structure 膜结构,6.1 Development and Characteristics 膜结构的发展与特点,What is membrane structure？,膜结构是指采用多种高强薄膜材料及辅助结构通过一定方式使其内部产生一定的预张力，并形成预应力控制下的某种空间形态，具有足够刚度以抵抗外部荷载作用的一种空间形式。包括了充气膜结构、张拉膜结构和索膜结构。,According to mechanical characteristics：,Inflatable Membrane Structure 充气式膜结构 Tensile Membrane Structure 张拉式膜结构 Skeleton Type Membrane Structure 骨架式膜结构,Membrane structure is a new kind of spatial structure, in which many kinds of high-strength membrane materials as well as assistant structures are used to produce some prestress, and certain spatial shapes are formed under the control of the prestress that have sufficient stiffness to carry the external loads.,Membrane Structure,Air-supported Membrane Structure 气承式膜结构,Inflatable Membrane Structure 充气式膜结构,Air-inflated Membrane Structure 气胀式膜结构,气胀式膜结构是指如同气球一般，将膜材包裹成封闭构件，向膜构件内部充气，使膜材产生张力，从而具有一定刚度，将多个膜构件组合形成整体受力体系。,气承式膜结构是指通过气压控制系统向建筑物室内充气，保持室内外一定的气压差，从而使膜材产生预张力，以保证结构刚度。,The air-supported membrane structure uses pressure control system to inflate the buildings to keep a certain degree of draught head inside as well as outside of the structure, and then prestresses appear in the membrane materials which ensure the stiffness of the structure.,The air-inflated membrane structure is just like a balloon formed by wrapping the membrane materials into a closed component , inflating the component to make the membrane materials prestressed as well as have enough stiffness and finally combing the membrane members.,Membrane Structure,Development of Inflatable Membrane Structure 充气式膜结构的发展,Willian Lancheste, British, put forward the first inflatable tent in 1971. 早在1917年，英国人W兰彻斯特（WillianLanchester）首次提出了气承式帐篷。 After World War 2, the United States began to use the membrane structure as the military facilities construction. 第二次世界大战后，美国实现了以膜结构作为军用设施的建造形式。 Walter Bird, American, built the first modern inflatable membrane structure, Doppler Radar Dome, in 1946. 1946年，美国人W勃德（Walter Bird）建成了第一个现代充气膜结构，多普勒雷达穹顶。,雷达防护罩 Doppler Radar Dome,Membrane Structure,In 1967, the first international inflatable structure conference was held in the German Stuttgart, which promoted the development of the inflatable structure. 1967年，第一届国际充气结构会议在德国斯图加特召开，促进了充气结构的发展。 In 1970, the World Expo in Osaka, Japan, David Geiger designed the United States Pavilion. 1970年，日本大阪世博会上，由D盖格设计的美国馆。 Fuji Museum was designed by Mamoru Kawaguchi as a sausage inflatable membrane structure. 世博会上，川口卫设计的香肠气胀式膜结构日本富士馆同样引人注目。,Development of Inflatable Membrane Structure 充气式膜结构的发展,日本大阪博览会富士馆 Fuji Museum,日本大阪博览会美国馆 The United States Pavilion,Membrane Structure,Michigan, the Pontiac “Silver Dome“ in 1975. 1975年建成的密歇根州庞蒂亚克“银色穹顶”, 平面为220m168m椭圆形。 Active Center of University of California, USA, in 1976. 1976年建成的美国加利福尼亚州圣克拉勒大学活动中心,平面为90.5m59.4m椭圆形。,密歇根州庞蒂亚克银色穹顶 The Pontiac “Silver Dome“,加利福尼亚州圣克拉勒大学活动中心 Active Center of University of California, USA,Development of Inflatable Membrane Structure 充气式膜结构的发展,Membrane Structure,Fangshan Beijing swimming pool and Anshan Nongwei natatorium were first applications of membrane structure in China. 1995年建成的北京房山游泳馆和鞍山农委游泳馆是我国第一次正式应用于工程的气承式膜结构，标志着我国内地膜结构工程发展的兴起。,Development of Inflatable Membrane Structure 充气式膜结构的发展,Indoor golf training field in Beijing Tongzhou starlake. 北京通州星湖园法利室内高尔夫练习场,Broadwell tennis hall in Beijing Chaoyang Park. 北京朝阳公园的博德维网球馆,Membrane Structure,Tensile Membrane Structure 张拉式膜结构,Skeleton Type Membrane Structure 骨架式膜结构,The skeleton type membrane structure is formed by covering the steel truss system or grid structure with membrane materials. Similar to the common structures, the membrane materials are used as the retaining structures while the skeleton is the load-bearing system in the skeleton type membrane structure . This kind of structure has been widely recognized and applied to the long-span stadium, exhibition center and so on. The membrane material only plays a role as envelope and the frame can form an independent force system. The skeleton type membrane structure is widely used in the stadium, exhibition center, transportation hub etc. 骨架式膜结构是在一般的钢桁架体系或网架结构等骨架上覆盖膜材，与常规结构相似，膜材仅仅起到围护结构的作用，骨架可独立形成受力体系，易于被工程界理解和接受，并广泛使用于大型体育场馆、展览中心、交通枢纽等。,Tensile membrane structure originates from cable net structure and is formed by prestressing the structure in certain ways to make it have certain shapes as well as stiffness. In the tensile membrane structure, the roof and its supporting structure constitute the load-bearing system. 张拉膜结构由索网结构发展而来，通过一定的方式给膜体施加一定的预张力，使其具有一定的形状和刚度，膜结构的曲面单元与其支承体共同构成了一个完整的结构受力体系。,Membrane Structure,Development of Tensile Membrane Structure 张拉式膜结构的发展,The tent built in Kassel Gardening Exhibition Design by the German scholar FreiOtto in 1955 is the earliest modern membrane structure in the word. 德国学者F奥托在Kassel园艺展设计建成的帐篷成为最早的现代张拉膜结构。 The German Pavilion at the Montreal International Fair was designed by German scholar FreiOtto in 1967, which is considered to be the first real sense of tensile membrane structure. 德国学者F奥托在加拿大蒙特利尔国际博览会上设计的德国馆，被认为是第一座真正意义上的张拉式膜结构建筑。,加拿大蒙特利尔国际博览会德国馆 The German Pavilion at the Montreal International Fair,Membrane Structure,The development of PTFE has greatly promoted the application of tension membrane structure. For example, the United States of California LaVine College Student Activity Center is the first membrane structure with PTFE built in 1973. 1973年建成的美国加利福尼亚拉维恩学院学生活动中心是用PTFE膜材建造的第一个膜结构。 Jeddah International Airport built in 1981 is currently the largest tensile membrane structure. 1981年建成的沙特阿拉伯吉达国际航空港是目前规模较大的张拉膜结构。,Development of Tensile Membrane Structure 张拉式膜结构的发展,美国加利福尼亚拉维恩学院学生活动中心 LaVine College Student Activity Center,沙特阿拉伯吉达国际航空港 Jeddah International Airport,Membrane Structure,Development of Tensile Membrane Structure 骨架式膜结构的发展,The Shanghai Stadium built In 1997 for the Eighth National Games is the first application of membrane structures in large permanent building in China. 1997年为第八届全运会兴建的上海八万人体育场是我国首次将膜结构应用于大型永久性建筑。 Shanghai Hongkou football Stadium adopted the membrane structure of the cable truss supported on the saddle shaped large cantilever. 1999年建成的上海虹口足球场采用了鞍形大悬挑空间索桁架支承的膜结构。,上海八万人体育场 The Shanghai Stadium,上海虹口足球场 Shanghai Hongkou football Stadium,Membrane Structure,In 2008 Beijing Olympic Games, the new ETFE materials were used in The National Stadium “Birds Nest“ and The National Swimming Center “Water Cube “. 2008年北京奥运会，国家体育场“鸟巢”(图6.1.13)和国家游泳中心“水立方” 均采用了ETFE这种新材料，分别是国内首次应用ETFE单层膜材和ETFE气枕的工程。,Development of Tensile Membrane Structure 骨架式膜结构的发展,国家体育场“鸟巢” The National Stadium “Birds Nest“,国家游泳中心“水立方” The National Swimming Center “Water Cube “.,Membrane Structure,The Central Corridor of The Guangzhou South Railway Station. 广州南站中央通廊位于站房的中部，采光屋面系统由1182个菱形的气枕组成。 Dalian Sports Center Stadium. The plane is oval. 大连体育中心体育场是第十二届全国运动会的主要比赛场馆之一，整体平面为椭圆形。 Tianjin YuJiabao Station Dome. The main part of the structure is covered by three layer ETFE cushion. 天津于家堡站房穹顶为京津城际铁路的延伸线，主要部分采用了三层ETFE气枕覆盖。,Development of Tensile Membrane Structure 骨架式膜结构的发展,广州南站中央通廊 The Central Corridor of The Guangzhou South Railway Station,大连体育中心体育场 Dalian Sports Center Stadium,天津于家堡站房穹顶 Tianjin YuJiabao Station Dome,Membrane Structure,6.1.2 Characteristics of Membrane Structure 膜结构的特点,Light weight, long span. 自重轻，跨度大 Various architectural appearances. 建筑造型丰富 Convenient construction. 施工方便 Cost savings 经济性 High safety 安全性 Good light transmission 透光性 Strong ability of self cleaning 自洁性,Advantages,Membrane Structure,There are also some disadvantages of the membrane structure, mainly in the following aspects:,Short service life. The service life of membrane material is generally 35 to 15 years. 膜材的使用寿命一般为1535年，虽然有些采用玻璃纤维膜材的实际工程使用超过25年仍保持良好性能，但与传统的混凝土或钢材相比仍有相当差距，与通常“百年大计”的设计理念不符。 The ability to resist the local load is weak. 膜结构抵抗局部荷载作用的能力较弱，屋面在局部荷载作用下会形成局部凹陷，造成雨水和雪的淤积，即产生所谓的“袋状效应”，严重时可导致膜材的撕裂破坏。 Maintenance cost is high in the process of the use of inflatable membrane structure. 充气膜结构使用过程中的维护费用较高，需要充气系统和控制系统时刻运转维持。 Constructors need professional training and the technology is difficult to master. 由于膜结构属于新型结构形式，设计与施工一般需要专门的膜结构公司完成，施工人员需要专业培训并持证上岗，技术难度较大。,6.1.2 Characteristics of Membrane Structure 膜结构的特点,Membrane Structure,6.2.1 Development of Membrane Materials 膜材的发展,ETFE是乙烯-四氟乙烯共聚物，具有高透光率，最高可达96%，有良好的抗老化性、耐火性、自洁性等优良性能，易加工。,Ethylene tetrafluoroethylene (ETFE) is a fluorine-based plastic. It has high light transmission ratio which can reach 96%, favorable anti-aging, anti-fire, self-cleaning properties, it is easy to process as well.,6.2 Development, Types and Basic Properties of Membrane Materials 建筑膜材的发展、类型和基本性能,Membrane Structure,（一） Fabric Membrane Material 织物类膜材,A kind of composite material with high strength and good flexibility. It mainly includes base material, coating, surface coating, adhesive and so on. 一种具有高强度、柔韧性好的复合材料。主要包括基层材料、涂层、表面涂层以及胶黏剂等。,6.2.2 Types of Membrane Materials 膜材的类型,某种织物类膜材 A fabric membrane material,织物类膜材的一般构造图 The general structure diagram of fabric membrane material,Membrane Structure,1. Base Material 基层材料,（一） Fabric Membrane Material 织物类膜材,The base material is composed of all kinds of fabric fibers which determine structural and mechanical properties of the material. There are different kinds of base materials such as carbon fiber, Kevlar (Fang Guan) fiber, polyester fiber, glass fiber and so on. According to the requirement of the strength of the structure, polyester fiber and glass fiber are usually selected as building membrane materials. 基层材料由各种织物纤维编织而成，决定材料的结构力学特性。基层材料的品种较多,碳纤维、Kevlar(芳纶)纤维、聚酯纤维、玻璃纤维等。根据建筑结构使用强度的要求, 建筑膜材一般选用聚酯纤维和玻璃纤维。,2. Coating 涂层,At present, various resin coating materials are available. Such as PVC (聚氯乙烯), PTFE (聚四氟乙烯, 商品名Teflon), Silicone (硅酮) and Flexurane（聚氨酯）. The first three coating materials are usually used in buildings.其中前三者为建筑常用涂层材料。,Membrane Structure,Membrane Structure,Membrane Structure,3. Fabric membrane material that are usually used 常用的织物类膜材,（一） Fabric Membrane Material 织物类膜材,Membrane Structure,（二）Non fabric membrane material 非织物类膜材,Compared to fabric membrane material, non-fabric membrane material is formed by thermal plastic with no base cloth. This material is isotropic and its tensile strength is relatively low. 与织物类膜材相比，非织物类膜材由热塑成形，没有基布，薄膜张拉各向同性，抗拉强度相对较低。,图6.2.2 ETFE膜材,Membrane Structure,ETFE(Ethylene Tetra Fluro Ethylene) The light transmittance 透光率 Tensile strength 抗拉强度 Aging resistance 抗老化性 Good self-cleaning 自洁性良好 Non flammable 不易燃,In 2008 Beijing Olympic Games, the main stadium “Birds Nest“ and the National Swimming Center “Water Cube“ adopted the ETFE membrane as building materials for the first time. Since then, the ETFE film began to develop rapidly in China and waswidely used.,（二）Non-fabric membrane material 非织物类膜材,2008年北京奥运会主场馆“鸟巢“和国家游泳中心“水立方“是国内首次采用ETFE膜作为围护材料的工程，向人们展示了ETFE膜材的无穷魅力。此后，ETFE膜在国内开始迅速发展，得到广泛应用。,Membrane Structure,6.2.3 Basic Properties of Membrane Materials 膜材的基本性能,（一） Basic Properties of fabric membrane material 织物类膜材的基本性能,1. Basic parameters 基本技术参数,Substrate weight（基材重量）： Expressed by fiber number and weight per area, generally bigger than 100g/. 以纤维纤度表示，同时以单位面积重量表征，一般大于100g/ ； Thickness of membrane materials（膜材厚度）： The distance between substrate coating and fiber surface is generally 0.31.2mm . 基材纤维与涂层表面的距离，常在0.31.2mm之间； Thickness of coatings （涂层厚度）： The distance between top surface and coating surface is generally 0.31.2mm . 纤维顶面与涂层表面的距离，常为0.10.3mm； Fiber weave（纤维织法）： Textile patterns of fiber include plain weaving, basket weaving and so on. Different weaving methods affect the mechanical properties of membrane materials.纤维的纺织方式，如平织、篮式编织等，不同的织造方法影响着膜的力学性能； Breadth（幅宽）： Width of membrane sheet is generally 5004500mm. 膜材卷材的宽度，常在5004500mm。,Membrane Structure,The mechanical properties of fabric membrane mainly depend on the fiber fabric. 织物类膜材的力学性能主要取决于纤维基布。 The tensile strength of membrane material is high, but the compressive stiffness and bending stiffness is almost zero. 膜材具有较高的抗拉强度，但抗压刚度和抗弯刚度几乎为零。,（2）Durability and Self-cleaning 耐久性与自洁性,（1） The Mechanical Properties 力学性能,Membrane Structure,The elastic modulus of the membrane material is low which is beneficial to form the complicated shapes of the structure. However, creep and relaxation will occur after the membrane material is pretentioned. 膜材的弹性模量较低，有利于膜材形成复杂的曲面造型。但膜材在张拉成形后的一段时间内，会产生徐变和松弛。,Membrane materials have excellent flame retardant and high temperature resistant performance. Generally speaking, PTFE membrane material is non combustible material and PVC material is flame retardant material. 具有卓越的阻燃和耐高温性能。一般情况下认为PTFE膜材是不可燃材料，PVC材料是阻燃材料。,（一） Basic Properties of fabric membrane material 织物类膜材的基本性能,（3）Elastic modulus 弹性模量,（4） Fire Resistance 防火性能,Membrane Structure,（5） Good Acoustic Performance 良好的声学性能,（一） Basic Properties of fabric membrane material 织物类膜材的基本性能,Fabric membrane material is a composite material. A lot of experiments show that, the membrane material has strong nonlinear and viscoelastic properties. However, in the actual stress range, the membrane material is still assumed as linear elastic in structure. 织物类膜材是复合材料，由大量的实验表明，膜材具有很强的非线性和粘弹性。但是，目前在做膜结构的结构分析时，在膜材的实际应力范围内，仍假定膜材为线弹性体。,（6） Linear Elastic 线弹性体假定,Membrane Structure,The deformation of membrane is large, and the strain is small. 由于膜材变形大，而应变小，因而在膜结构分析中假定膜材保持正交异性且方向不变。,The determining factors of permissible stress in design of membrane structure include the structure safety coefficient and reduction coefficient. 膜结构设计中膜内允许应力的确定因素有:结构安全系数和折减系数。,（一） Basic Properties of fabric membrane material 织物类膜材的基本性能,Membrane Structure,（二） Basic Properties of non fabric membrane material 非织物类膜材的基本性能,Strong and durable 厚度通常为50300m，非常坚固、耐用； Tensile strength 单层膜抗拉强度在35MPa以上，断裂延伸率大于350%； High light transmittance 具有高透光率，透光率在50%96%之间,可以通过调节表面印点覆盖率和材料厚度来调节光强度和紫外线的透过率； Self cleaning 张拉后的膜面极为光滑且有自洁能力； Service life 平均使用寿命30年左右； Nonflammable ETFE膜材不易燃, 且在燃烧融化后会自行熄灭, 达到B1、DIN4102防火等级标准。,ETFE(Ethylene Tetra Fluro Ethylene) 乙烯-四氟乙烯共聚物,Membrane Structure,1. The tensile test at room temperature 常温下单向拉伸试验,两个屈服点，可采用三折线简化模型。,第一屈服应力平均值为13.915.8MPa，第一屈服应变平均值为2.1%2.3%， 第二屈服应力平均值为21.022.2MPa，第二屈服应变平均值为14.4%15.4%，弹性模量建议按割线弹性模量取650MPa。,（二） Basic Properties of non fabric membrane material 非织物类膜材的基本性能,Two yield points. The model can be simplified by using the three line.,The first average value of the yield stress is 13.9 15.8MPa , The first average value of the yield strain is 2.1%2.3% , The second average value of the yield stress is 21.022.2MPa , The second average value of the yield strain is 14.4%15.4% , According to the recommendations of secant elastic modulus, the elastic modulus is 650MPa.,Membrane Structure,2. The tensile test at low temperature 低温下单向拉伸试验,随着温度的降低，ETFE薄膜应力-应变曲线在强化前几乎变成连续的曲线。与常温相比低温下ETFE薄膜的抗拉强度有较大提高，而延性则明显降低。 ETFE薄膜割线模量变化幅度在10以内，可忽略低温对其影响。,ETFE薄膜低温单向拉伸应力应变曲线 The ETFE thin film stress - strain curve on the tensile test at low temperature,（二） Basic Properties of non fabric membrane material 非织物类膜材的基本性能,With the decrease of temperature, stress - strain curve of the ETFE almost turned into a continuous curve before strengthening. Compared with under normal temperature, the tensile strength of ETFE films under low temperature is greatly improved, and the ductility is significantly reduced. However, the effect of low temperature on ETFE film can be ignored when its secant modulus variation is less than 10%.,Membrane Structure,3. Cyclic tensile tests at room temperature 常温下循环拉伸试验,Elastic stage （弹性阶段）： No obvious residual strain; Good elastic properties ; Design according to the assumption of elastic material. 无明显的残余应变，呈较好的弹性性能，设计时可按材料弹性假定进行。 Yield stage （屈服阶段）： The phenomenon of stress relaxation happens; Large residual deformation after unloading; Enlarged the elastic limit ; Stress hardening phenomenon happens; 薄膜出现应力松弛现象，卸载后将产生很大的残余变形，弹性极限提高, 出现了应力硬化现象，设计时应充分考虑。,ETFE material with long time stretching will produce significant creep. Its size is related to the tensile stress and temperature. ETFE 薄膜受到长时间拉伸时会产生较为显著的徐变, 其大小与拉伸应力、温度密切相关。,（二） Basic Properties of non fabric membrane material 非织物类膜材的基本性能,Membrane Structure,6.3 The form of membrane structure 膜结构的形式,6.3.1 Classification of membrane structure 膜结构的分类,常用的一种分类方法是将膜结构分为充气式膜结构、张拉式膜结构、骨架式膜结构。,Inflatable Membrane Structure 充气式膜结构,Tensile Membrane Structure 张拉式膜结构,Skeleton Type Membrane Structure 骨架式膜结构,Membrane Structure,6.3.2 The selection of membrane structure 膜结构的选型,膜结构的设计核心,Inflatable Membrane Structure(充气式膜结构): The economic superiority is very obvious for long span structures. However, it is difficult to maintain and have limited shapes, it is only applied to some specific areas. 虽然当用于超大跨度结构时其在经济上的优越性十分明显，但是维护困难，造型受限，除某些特殊领域外，应用越来越少。 Skeleton Type Membrane Structure(骨架式膜结构): It is the most widely used type and its shape or span depend on its skeleton 。 目前应用最广，结构的形式、跨度均取决于其骨架结构。,膜结构的选型,Control the boundary conditions and geometry of the supporting structure in order to find the best film surface morphology. 控制结构的边界条件以及支承结构的几何形状，从而找到满足设计要求的最佳膜面形态。,Selection of membrane surface shape and supporting system of membrane structure .膜面形状的确定和膜结构支承体系的选择。,Membrane Structure,Types of membrane structure is also affected by the stress state of the body. The initial shape of membrane structure should ensure certain curvature . To determine reasonable drainage slope . Reduce accumulation of snow.,6.3.2 The selection of membrane structure 膜结构的选型,膜结构的型体不仅由建筑设计所决定，还受到结构受力状态的制约。 膜结构的初始形状应保证具有一定的曲率。 还应根据建筑物的使用特点，合理确定排水坡度，确保膜面排水顺畅。 在雪荷载较大的地区，应尽量采用较大的膜面坡度以避免或减少积雪，并应采取必要的防积雪和融雪措施。,Attention 注意,Tensile Membrane Structure(张拉式膜结构): The membrane materials have the functions of carrying the loads as well as enclosing the structure. The shapes of the structure can be determined by the factors like plane shape, boundary condition, architectural appearance, architectural