100 key points in the design of glass curtain wall joints

1 curtain wall overview

The building curtain wall to obtain considerable development in our country, some systems to achieve or exceed the level of foreign countries, the emergence of a large number of high-quality projects and high-tech projects, but there are also many problems in engineering, even the problem of security is not excusable.

Through the discussion of engineering inspection, laboratory test and technical meeting in recent years, it is found that these problems can be avoided by means of design. So prone to problems in engineering are summarized, summed up as 100 design taboo, I hope to design the level of China's curtain wall industry can help improve, promote the healthy development of the curtain wall industry.

2 glass curtain wall

Glass curtain wall is a widely used exterior wall system. The dominant position in the exterior walls of the building is unshakable, and many excellent projects have appeared.

2.1 the direct adhesion between fluorocarbon coating and structural adhesive

Some adhesive sealant and fluorocarbon coating structure is not up to the requirements of the curtain wall, therefore, the seal between the hidden frame glass curtain wall component side frame and a glass panel between the fluorocarbon coating joint measures should be taken to improve adhesion. There are a variety of measures available: (a) primer, then make the injection plastic structure, but some experts believe that this method is not reliable, which belongs to the "two skin", there is no more convincing positive reports to prove that this method is effective, so it still needs further observation and research; (b) combined with section structure, direct bonding structure adhesive part and other parts of section, directly bonded structural adhesive parts by anodic oxidation treatment; (c) a fluorocarbon coating process, treat bonding parts of shelter, keep the surface still for anodic oxidation; (d) to take remedial measures, the coating with sandpaper to remove the adhesive surface. By the natural oxidation (about 5 m).

2.2 self tapping screw connection

The self tapping nail joint is a general connection or positioning connection. As a structural connection, its reliability is poor.

2.3 steel aluminum profiles mixed use (aluminum clad steel)

Square steel pipe inner surface is not easy to realize the shot peening, quality problems of hot galvanizing, resulting in corrosion resistance is low; steel aluminum clearance should be more strict, or can not reach the common force, difficult to prevent double metal corrosion.

2.4 short gland

The frame curtain wall is pressed by gland, which is convenient for realizing equal pressure cavity, and on the other hand, it can be clamped with the buckle cover. The use of discontinuous gland (short gland), although it can reduce costs, but there will be uneven glass, pressure chamber can not be formed and so on.

2.5 the connection between the beams and columns is connected by two points

Curtain wall beam will often appear "head down" phenomenon, the reasons may be: (1) do not meet the requirements of bearing capacity of beam; (2) connecting beams and columns are relatively weak, such as beam column connections between the two bolts (screws) connection, because of its torsional performance is poor, resulting in curtain wall beam twist.

2.6 large section decorative strips without drip line

Large section of decorative strip on the surface will accumulate ash, if not set the drip line, will cause the curtain wall surface more flow mark. If a drip line is arranged at the front end of the decorative strip, the mixture of water and dust can be effectively prevented from flowing to the surface of the curtain wall.

2.7 trim cover fit with the live bayonet

The decorative cover is connected with the bayonet of the extrusion section, the size of the bayonet is fixed, the precision is high, and the reliable connection can be realized. The bayonet formed by the screw connection can not reach the requirement and the connection is unreliable.

2.8 the opening cavity is not provided with hot and dense wires

Hot and dense wire is widely used in the design of energy-saving aluminum alloy window, but it is less applied in the opening of building curtain wall, which leads to low energy saving effect of the opening of curtain wall.

2.9 the non frame curtain wall adopts the spacer plate

Generally, the frame curtain wall and semi hidden frame curtain wall are pressed by pressing plate (block), the distance is generally not greater than 300mm, there are two kinds of fixed distance and non fixed distance pressboard. Fixed pitch plate by connecting bolts after the crimping gap is fixed, the pressing force on the glass panel side frame is consistent, easy absorption structure and temperature deformation, reduce friction and noise, and can avoid pressing pressure caused by the uneven image distortion phenomenon of glass panel.

2.10 false clear frame hidden frame design is not hidden curtain wall

The false frame is usually decorated with a decorative strip at the joint of the hidden frame curtain wall, so as to achieve the decorative effect of the frame curtain wall. The design of the frame curtain wall shall be adopted to design the insulating glass and structural adhesive, that is to say, the second sealant shall be sealed with silicone structural adhesive. If polysulfide sealant is used as the second seal of the insulating glass, there are still unsafe factors, although it may not be destroyed by ultraviolet radiation.

2.11 hidden frame, insulating glass, lower plate, no pallet

The structural adhesive of insulating glass can endure shearing force for a long time, which is harmful to the service life of structural adhesive. Therefore, the support plate should be installed in the lower part of glass in JGJ02. The plate and beam direct connection is more reasonable, can be designed as a card connection or bolt connection; the auxiliary frame by bolts and glass components of the connection may affect the structural adhesive play note, the existence of quality defects, we recommend caution.

2.12 insulation bars bear shear

The heat insulation strip has the function of transmitting the structure and reducing the heat transmission in the heat insulation section, and is widely adopted in the curtain wall section bar. The strip type structure adopts a composite production line to press the heat insulation strip and the aluminum alloy bar forcibly. Therefore, the cold work hardening phenomenon exists in the pressing parts of the heat insulation strip and the aluminum alloy profile, and even exists some micro crack defects. If the curtain beams are made of heat insulation profiles, structural measures shall be taken to avoid the heat insulation bars bearing shear and prevent the heat insulation bars from damaging the connecting parts of the aluminum alloy profiles.