Membrane structure is a perfect combination of architecture and structure. It is a kind of space structure which combines high-strength flexible membrane material with supporting system to form a stable surface with certain stiffness and can bear certain external loads. Its shape is free and lightweight, flame retardant, easy to make, fast to install, energy saving, easy to use, safety and other advantages, so it has been widely used all over the world.
Modern membrane structure engineering is a high-tech project which integrates architecture, structural mechanics, chemical engineering, material science and computer science. Because of its unique performance and strong visual impact effect, it was quickly accepted by people, and an irresistible trend of development emerged.
In recent years, with the deepening of the concept of architectural space and the continuous improvement of scientific means, "returning to nature" and "bathing in the warmth of nature" have become the mainstream of the development of modern architectural environment. Indoor and outdoor vision is becoming more and more blurred, and there are many infiltrating uncertain spaces, such as hall decoration, patio, four seasons hall, animal and botanical gardens, Park square, viewing platform, stage, stadium, sports stand, cultural and entertainment venues, etc. Because of the transparency of the film, daytime sunlight can diffuse through the film to achieve almost the same natural effect as outdoor, so the film structure can create a space form comparable to the natural environment.
At present, the development of domestic membrane structure is exciting. With the construction of some large-scale gymnasiums and airport halls, as well as the holding of Shanghai World Expo, Guangzhou Asian Games, Beijing Olympic Games and other international events, the development of membrane structure in China has brought opportunities. PVDF, PTFE, ETFE and other membranes are the mainstream of the market. They are used more and more widely, many companies, research institutes and universities are conducting research on membrane materials, while introducing world-class production equipment and technology, we should digest, absorb and improve innovative production processes. At present, our country has the independent intellectual property rights of PVDF and PTFE membranes, and the performance also meets the requirements of similar product abroad.

Structural classification
From the structural form, membrane structure can be simply summarized into three categories: inflatable, skeleton and tension. 
1.1Air Supported Membrane Structure
The inflatable membrane structure relies on the pressure difference between the inside and outside of the membrane surface to maintain the shape of the membrane surface. For the air-supported flushing film structure, the surface after inflating is mainly spherical or cylindrical, and the shape may not have too many choices to make its application area narrow while the air-closure is required in space. However, the cost of the inflatable cable-membrane system is low, the construction speed is fast, and it has obvious advantages under specific conditions.
1.2Framework Membrane Structure
Because of the balanced force of its structural skeleton system, skeleton cable-membrane architecture is often used by architects. The combination of membrane tension and skeleton forms forms forms forms skeleton cable-membrane architecture, which achieves the effect of combining rigidity with flexibility.
1.3Tensioned Cable-Membrane Structure
Tension cable-membrane building is the essence and representative of cable-membrane building. Membrane surface in tensioned cable-membrane structure maintains its shape by prestressing. Membrane is not only the enclosure of building, but also the structure to resist external load effect. Because of the plasticity of its architectural image and the high flexibility and adaptability of its structural form, it is widely used. The tensioned cable-membrane structure can be divided into cable-net type and ridge-valley type. This system is expressive and has strong structural performance, but its cost is slightly higher and its construction accuracy is also required. For the tensioned membrane structure, any additional support and modification are superfluous, and its structure itself is the shape; the beauty of the tensioned membrane structure lies in the perfect combination of "force" and "shape".
Application area
Sports facilities: stadiums, fitness centers, etc.
Transportation facilities: airport, railway station, bus station, expressway toll station, gas station, etc.
Cultural Facilities: Exhibition/Conference Center, Theatre, Museum, Zoo, Aquarium, etc.
Landscape facilities: building entrance, swimming pool shading, rest corridor, corridor, public square, Park sketches, landmark buildings, etc.
Commercial facilities: shopping malls, restaurants, pedestrian streets, etc.
Industrial facilities: factories, warehouses, sewage treatment centers, logistics centers, greenhouses, etc.
Architectural form
As far as shape is concerned, it is very important for architects. The shape of a building with a general structure is usually determined by the architect first. Membrane structure is different. First, its deformation is larger than that of general structure. Secondly, its shape is gradually formed in the construction process. There is a problem of shape determination, which requires the participation of structural engineers. It is necessary to determine the initial shape of the structure under the initial load, that is, the equilibrium position of the structure system under the action of membrane dead weight (sometimes cable) and prestress. In the preliminary design stage, the roughly geometric shape is set according to the building requirements, and then the membrane surface is prestressed to withstand tension. The shape of the membrane is changed accordingly. After adjusting the prestress continuously, the ideal geometric shape and stress distribution can be obtained.
Membrane structure design breaks the traditional practice of building first and then structure design, which requires close integration of architectural design and structure design. In the design process, architects and structural engineers sit together to determine the shape of the building and make the necessary computational analysis. At this time, the plane shape, elevation requirement, fulcrum setting, material type and prestress size of the designed building will become the factors that restrict each other. A perfect design is also the result of the above contradictions and unification.
Engineering characteristics
1. Artistry
Membrane structure is based on modelling and colorology. It can combine natural conditions and national customs to construct curves and shapes which are difficult to achieve in traditional architecture according to the architect's creativity. Membrane structure - the architect's romantic idea, enjoying the natural romantic space.
2. Economical efficiency
For long-span space structures, if membrane structures are used, the cost is only half or less of that of traditional buildings, especially in the construction of long-span buildings for short-term application, which is more economical. Moreover, the membrane structure can be disassembled and moved easily.
3. Energy saving
Because the film itself has a good transmittance (10-20%), natural diffuse light can be obtained in the daytime in building space, which can save a lot of energy for lighting.
4. Self-cleaning
The protective coatings (such as PVDF, PTFE, etc.) coated on the surface of the membrane have the characteristics of high temperature resistance and do not stick to itself, so the dust falling on the surface of the membrane can be washed by rainwater naturally to achieve self-cleaning effect.
5. Large-span unshielded visual space
Membrane structure uses membrane instead of traditional building materials, and its weight is only one-thirtieth of that of traditional buildings. Membrane structure can fundamentally overcome the difficulties encountered by traditional structures in the implementation of long-span (unsupported) buildings, and create a huge visible space without shelter.
6. Short construction period
All the processing and production in membrane construction are completed in the factory, which can reduce the construction time on site and avoid the construction crossover. Compared with traditional construction projects, the construction period is shorter.