As a unique design in modern architecture, the glass curtain wall not only embodies the combination of architecture and aesthetic structure design but also fully reflects the multiple functions of glass. For example, the permeability of the glass curtain wall is very good through the glass, and the field of vision is very large so that the interior and exterior environments of the building are connected and blended. The glass curtain wall has good process performance, the glass curtain wall supporting components are processed meticulously, the surface is smooth, has a good sense of craftsmanship and artistic sense, can adapt to any geometric shape, produces rich changes in the building shape, and can fully reflect the designer's imagination and creativity. A very big highlight of the current use of glass curtain walls is that the use of various energy-saving curtain wall glass greatly reduces the energy consumption of the building. Nevertheless, in the past period of time, many construction projects have been troubled by glass curtain walls. Some glass curtain walls with unreasonable design, material selection, and construction have been criticized by all walks of life due to their broken glass, glass falling, water, and air leakage, and other problems.
Due to various unreasonable applications of glass curtain walls, there are many problems that are likely to cause, such as high burst rate of tempered glass, failure of structural glue, poor fire resistance of curtain wall glass (ordinary), failure of glass curtain wall supporting structure and failure of glass curtain wall fixing devices, etc. This article will analyze and demonstrate various safety misunderstandings in the glass curtain wall and discuss with you how to solve the problem.
There are many reasons for glass breakage. The following first analyzes and demonstrates the glass breakage caused by impurity nickel sulfide and thermal stress.
1. Glass burst caused by impurity nickel sulfide
The practitioners related to glass curtain wall introduced that nickel sulfide is an inevitable harmful impurity in the glass production process. Nickel sulfide itself does not cause any damage to the glass. However, when the curtain wall glass containing nickel sulfide is installed on the curtain wall, the external temperature rises, resulting in the volume of nickel sulfide. Tiny changes cause tiny cracks in the glass. These cracks release the internal energy after passing through the tension layer of the tempered glass, causing the glass to break.
Glass burst caused by impurity nickel sulfide 1
The solution is to start from the source first. Glass manufacturers should monitor the entire glass manufacturing process to minimize the contact between nickel-containing materials and glass raw materials. Secondly, for the monitoring of the curtain wall glass after installation, there is already a technology in foreign countries to check whether nickel sulfide impurities exist in a photographic way. If it contains, it must be replaced in time to prevent the glass from breaking and hurting people. It is also possible to replace the single-piece tempered glass and tempered hollow glass with laminated glass. If the nickel sulfide impurities cause the glass to break due to deformation, the shards will still adhere to the film, so that glass rain will not form and cause damage to the ground personnel.
2. Glass breakage caused by thermal stress
Thermal stress is an important cause of the glass curtain wall breaking. There are many reasons for the glass curtain wall to be heated, but the main heat source is sunlight. When the sunlight shines on the surface of the glass curtain wall, the glass will be heated and expanded. The mid-point part of the glass expands uniformly at the same time, but if the edges and the inside of the glass are heated unevenly, tensile stress will be generated inside the glass. When there are cracks or micro-cracks on the edge of the glass, these defects are easily affected by thermal stress. As the temperature difference increases, thermal stress causes cracks to gradually increase, and the glass breaks.
Glass breakage caused by thermal stress 1
The solution is to first finish the glass edge, and use fine grinding or polishing to reduce the existence of small cracks; secondly, the glass is tempered to enhance the ability of the glass to resist temperature changes; the third is in During glass processing, handling, and installation, the glass must be properly protected. Be careful not to collide or rub the edge of the glass with other hard objects. Strictly follow the operating procedures, especially during the installation process, if the frame is not suitable (too small or too small). Distortion), remember not to use pliers to pinch the corners of the glass, be sure to correct the frame to adapt to the size of the glass.
3. The glass curtain wall has poor fire resistance
The glass curtain wall is a non-flammable material, but it can be softened or even melted in front of a fire. Therefore, in building design, we must fully consider the fire protection requirements of the building. The general glass curtain wall has low fire resistance, fire resistance integrity, and fire resistance and heat insulation, and it only takes a short time for the glass to break in a fierce fire.
The glass curtain wall has poor fire resistance 1
The solution: in the actual construction process, the designers carry out different designs according to the different fire protection requirements of the building. For buildings with general fire protection requirements, glass bricks, tempered glass, small flat glass, etc. are used for the glass. For buildings with high fire protection requirements, the curtain wall glass uses laminated glass, single-piece fire-resistant glass, composite fire-resistant glass, and fire-resistant hollow glass. Composite fireproof glass is currently widely used fireproof curtain wall glass. Among the major fireproof glass manufacturers in the domestic market, diamond glass is more prominent in overall fireproof and flame retardant performance, because when a fire occurs, within a certain period of time The glass on the fire-facing surface bursts due to heat, but due to the existence of the fireproof film, the glass is adhered to the film and does not fall off, maintaining the integrity of the glass. At the same time, because the film itself has a fire prevention effect, it not only prevents the spread of the fire, but also ensures that the temperature of the backside fire surface does not rise rapidly, and the spread of the fire is controlled.
4. The curtain wall glass structural glue failure
Because the glass curtain wall has been affected by the unfavorable factors of the natural environment for a long time, such as wind, sun, rain, ultraviolet radiation, earthquake, etc., it is required that the glass curtain wall must have weather resistance, durability, and corrosion resistance. It is used as a bonding material. Structural glue has become the focus of attention. In some cities with high-rise buildings in developed countries, glass curtain walls have been used as building materials earlier, and curtain wall glass falling incidents have occurred from time to time. How to determine the failure of a certain piece of glass structural glue can be said to be more difficult, but it is more difficult. To ensure the safety of personnel and vehicles, it is a huge expenditure to replace the glass curtain wall in a large area. In the face of this situation, the owner is in a dilemma.
The curtain wall glass structural glue failure 1
The solution: first restrict the use of the hidden frame glass curtain wall, and protect the glass curtain wall that has passed the warranty period.
Such as setting up fences, green belts, and hanging curtains around the glass curtain wall to prevent the falling glass from hurting passing pedestrians and vehicles. The second is to use exposed frame and semi-hidden frame glass curtain wall as much as possible, because even if the structural glue fails, due to the support and constraints of the frame, the probability of glass falling will be greatly reduced. At the same time, relevant practitioners should pay attention to the branding of international standard certified adhesives. In the past 20 years, there have been a series of certification parameters and standards for building structural silicone adhesives in various countries around the world. This is to control the quality of structural adhesives and unify performance standards in the industry. , Improve the safety of glue for glass curtain walls.
5. The glass curtain wall support structure fails
Not all problems with glass curtain walls are caused by the glass itself. Sometimes the failure of the frame structure supporting the glass can also cause safety problems for the glass curtain wall. The frame structure used to support the glass is often the weak link of the glass curtain wall. If the frame system design is unreasonable, the frame structure cannot withstand the pressure inside the building and then deforms, causing the glass to break.
The glass curtain wall support structure fails 1
The solution is to carry out a fatigue-relieving experiment on the frame structure during the design process, and then design the corresponding curtain wall glass according to its ability to relieve fatigue to prevent long-term overload operation of the frame.
6.The glass curtain wall fastener fixing device fails
All glass curtain walls rely on fastener fixing devices to combine the curtain walls and fix them on the building. However, unforeseen flaws in the fastener fixing device may cause serious structural problems and even cause the curtain wall glass to fall.
The glass curtain wall fastener fixing device fails 1
The solution: Before installing the glass curtain wall, perform necessary inspections on the fastening of the fasteners. Only after passing the inspection can it be installed and used on site. In addition, for the curtain wall glass falling caused by the loosening of the fixing bolts, in the actual construction process, we use special locking nuts to lock the bolts to prevent the bolts from slipping and falling or use special washers to ensure that the bolts will not fall off after being tightened. Curtain wall hardware accessories systems such as fasteners and fixings need to have unified integrity, and the combination and matching effect is expected to be good, so the manufacturer's centralized quality control management must be managed.
Other problems caused by the glass curtain wall
The glass curtain wall causes more than the above problems. Due to the large area use of the glass curtain wall, there will be some related problems caused by improper design, construction, and material selection. However, as designers, producers, and users, as long as they fully understand them and maximize their strengths and avoid weaknesses, the glass curtain wall is still the choice of high-rise building envelope structure because of its light structure, easy maintenance, and beautiful appearance. At the same time, it is also modern highlight of the building.