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Node detail design is the most important technical link of membrane structural engineering design. It not only affects the overall architectural and local architectural artistic properties of membrane structures, but also influences the fabrication, installation, structural safety, and cost of membrane structures. The structural design of the connection node fully embodies the aesthetics, professionalism, comprehensiveness and precision of the membrane structure design, and is the soul of the membrane structure design. The specific form of the membrane structure node is complicated and very rich. According to the role of membrane and connection, it can be divided into membrane node, membrane and rigid boundary, membrane and flexible boundary cable; according to node position and configuration, it can be divided into vertex (high or low point), ridge line, valley line, and angle. Nodes, etc. The common principles of node design mainly include: structural design, architectural design, geometric design, materials and manufacturing processes, installation and maintenance, pre-tension introduction mechanism, and cost control.

(1) Structural design Any connecting node shall transmit the force path directly and concisely, effectively transfer the internal force, and have a constraint mechanism coordinated with the movement. At the same time, it has enough structural strength to meet the “strong node” idea, and the node generally does not precede structural component destruction. And the necessary redundancy. The high and low points and corner junctions have large stress concentration effects on the film, and the node details must be reliably diffused and stress transmitted. Gas-tight, airbag-type membrane special nodes must meet hermeticity.

(2) The design of the architectural design node is coordinated with the overall design of the membrane construction, and the appropriate materials and processes are selected to meet the anti-corrosion and waterproof requirements of different construction environments. As for the beauty of the node, no matter how important it is, it cannot be overemphasized. Any node design should be placed in a specific local and overall environment, and aesthetics should be used to examine and consider, such as the smooth and delicate shape of the connector, continuous smoothness, symmetry and balance of the force flow, and lightness. Spirit simplicity and so on.

(3) Geometric design Fine geometric design is particularly important for the connection of membrane structures to nodes. First, carefully analyze the geometrical relationships of the connected nodes, such as spatial geometry, connections and constraints, and positioning; then consider the smooth coordinated connection of the membrane surface, the necessary dimensions and space, and the volume and overall ratio of the nodes.

(4) Materials and production processes Materials and production processes are mainly based on the overall positioning of membrane construction, which has a direct impact on the cost.

(5) The installation and maintenance of the connection node should facilitate the installation of the membrane and cable, the installation of the pressure plate and the secondary membrane, the effective introduction of the membrane tension, and the necessary adjustment mechanisms for easy maintenance or replacement. In addition, necessary maintenance and cleaning facilities are designed for important public membrane buildings.

(6) The cost and budget node design must be based on the cost budget, using economic and rational design techniques. Different film structure systems, node systems, materials, and manufacturing processes have large differences in cost. Personalized membrane architecture and node details are always complementary and indispensable.

The light transmission of architectural fiber membranes is often considered to be the most valuable feature of tensile membrane structures. During most of the daytime, the spectral transmittance of the film (typically 10% to 15%) provides the possibility of not using artificial lighting, thus saving a lot of energy to compensate for higher heating energy consumption.

      Although the indoor illumination is high, the illumination is only one of many factors that form the indoor visual environment. The selection of membrane materials, structural topography and detailed structures all have important effects on the visual environment. Therefore, the visual environment of the building should be taken into account in the preliminary design stage. In addition to meeting the illuminance requirements for indoor activities, the users' perceptions and other subjective needs should also be met. Light characteristics.

1. High lighting factor
      The sunlight that hits the roof is transmitted into the room in the form of diffuse light. From the inside, the roof becomes a continuous bright surface, and its strength changes due to the relative position of the roof and the sun.
The daylighting coefficient of the indoor space of the tension membrane structure (ie, the ratio of the natural light level of the indoor and outdoor surfaces) can generally be as high as 10%; while in traditional buildings, the light can only enter the room from a limited light window, and its lighting factor is less than 3 %. Even on cloudy days, the light level in the membrane structure can meet the basic requirements of most activities.

2. No glare
      Since the transmitted light and the reflected light entering the film structure room are diffuse light, glare is less likely to occur, but the arrangement of the glass lighting area and the shade should be taken into consideration to avoid glare caused by the direct light thereof.

3. The color feels good
      People in the room will have a good color perception of white or beige materials, because these two colors exhibit a characteristic of linear spectral transmission of visible light. The degree of transmission increases with the wavelength of the transmitted light, which makes the transmitted light slightly warmer than the emitted light. The transmission spectrum is related to the fiber and its properties, the thickness of the coating, and the additional surface layer, and the manufacturer should give more detailed information. Relative to coated PVC. The transmission spectrum of the polyester fiber membrane and the PTFE-coated glass fiber membrane is more uniform.

Membrane structure

As an important branch of the modern spatial structure system, the membrane structure is a brand-new architectural structure form. In addition to rich and colorful shapes, it also has excellent architectural characteristics, structural characteristics, and appropriate economics. The membrane structure umbrellas not only have the superior heat insulation ability, but also have the features of stylish and beautiful design, and they also have a good effect of protecting the sun from rain.
1. First, direct sunlight can be blocked to prevent overheating in the umbrella; secondly, good ventilation effect can be maintained while insulative. Membrane structure umbrellas commonly used membrane materials are two major categories of PVC and PTFE, both of these materials are fire-resistant flame retardant, high strength, good durability, not affected by ultraviolet light, long life and other excellent performance. It is widely used in communities, parking lots, stadiums, parks, and plazas.

2. The membrane membrane umbrella is composed of a variety of high-strength membrane materials and reinforcing members (skeletons, steel columns, or steel cables). As a covering structure, it can withstand certain external loads.

3. Imported tensile film material, able to resist the typhoon of Class 10 (38m/s), quality assurance for more than 5 years, can be used for outdoor shading, diversification of specifications and shapes and colors, suitable for park landscape pieces, or private courtyard , outdoor cafes or tea houses. The structure is sturdy, beautiful and lightweight, fireproof, waterproof, anti-aging, and resistant to UV and air pollution.
The unique and stylish shape of the membrane structure umbrellas is a goal that people are looking for. For example, constructing a leisure parasol in the heart of the neighborhood near the residential area not only vividly embellishes the environment, but also more importantly for people. Provides convenience.

Membrane materials are polyester fiber fabric or PVDF, PVF, PTFE and other surface coatings, together with high-quality PVC composed of a stable shape, and can withstand a certain load of construction textiles, its life is due to different surfaces Different coatings can generally reach 12-50 years.

    There are a wide variety of membrane materials used in membrane structures, and different countries have different requirements for membrane materials. However, depending on the materials, they can be divided into three major categories: ETFE membranes, PTFE, and PVC, but the most Commonly used membrane materials are PTFE and PVDF membrane materials.

    The PVDF film material refers to a composite material formed by coating a polyester fiber-woven base fabric with PVC (polyvinyl chloride) and then adding a 100% PVDF (polyvinylidene fluoride) surface coating. PVDF membrane material has good self-cleaning property, moderate price, convenient transportation and installation, and is more widely used in all kinds of construction fields. Its life span varies with different surface coatings. Generally, it can be achieved for 10-25 years. Ti02 (titanium dioxide) PVC film material with extremely high self-cleaning properties.
     1). This kind of material is fire-retardant material, fire-resistant special grade B1;
     2). The thickness is 0.6-1.2mm; the light transmittance is between 6%-12%; the strength is generally between 3500-9000N/5cm.

    The PTFE membrane material is Teflon, a composite material formed by coating a very thin glass fiber woven base fabric (Poly Tetra FIuoto Ethyiene, PTFE for short), PTFE The main features of the membrane material are high strength, good durability, fire resistance, flame retardance, and good self-cleaning properties. It is not affected by ultraviolet rays, and has high light transmittance, light transmittance of 80%, heat energy reflectance of 73%, and heat absorption. Rarely, it is because of the invention of this epoch-making membrane material that the membrane structure construction has become a modern permanent building.
     1). This type of material is non-combustible material, refractory grade A1, permanent membrane material, with a service life of more than 30 years;
     2). The thickness is 0.6-1.2mm, the light transmittance is between 8% and 18%, and the strength is generally between 3500-9000N/5cm.

    ETFE film material (Ethylene Terafluo Ethylene abbreviated ETFE), ETFE's Chinese name is ethylene-tetrafluoroethylene copolymer

    The thickness of the film material is usually less than 0.20mm. This kind of film material is light and has a good light transmittance of 95%. It is called "soft glass" and has good toughness, high tensile strength, and is not easily torn. The ductility is more than 400%. Weather resistance and chemical resistance, melting temperature up to 200 °C; can effectively use natural light, save energy; good acoustic properties. The self-cleaning function makes the surface less stainable, and the contaminated dirt can be carried away by rain erosion. The cleaning cycle is about 5 years. The ETFE film is completely recyclable, can be reused to produce new membrane material, or can be separated. After the impurities are produced in other ETFE products, the ETFE film has a service life of at least 35 years and is an ideal material for a permanent multi-layer movable roof structure.