Key Factors Affecting the Safety and Application of Glass Curtain
Key Factors Affecting the Safety and Application of Glass Curtain
Regarding the self-explosion rate of tempered ig glass, the statements of domestic manufacturers vary from 0.3% to 3%, and they are not completely consistent. This means that even if it is qualified tempered ig glass, it still has a certain amount of self-explosion rate after passing all the audits and acceptance. For some large-area (more than 5 square meters) and thick plates (a single piece of ig glass exceeding 20mm or a plate composed of two pieces of tempered ig glass), the actual self-explosion rate may be higher.
At present, the main solutions to the "self-explosion" of tempered ig glass from the inherent nature of the material are the hot dip treatment process and the high-quality ultra-white ig glass. Heat soak treatment (Heat Soak Test, HST for short) is also known as homogenization treatment. The main function is to promote the rapid completion of the crystal phase transformation of nickel sulfide in the hot-dip furnace of the tempered ig glass factory, so that the tempered ig glass that may explode after use is artificially broken in the hot-dip furnace of the factory in advance, thereby reducing the use of after installation. Tempered ig glass explodes. According to foreign experience, the self-explosion rate of tempered ig glass after homogenization treatment can be reduced to less than 0.15%.
Ultra-white ig glass is a flat ig glass with high visible light transmittance, produced by float process, with Fe2O3 content not more than 0.015%. Ultra-white ig glass, because its material selection basically does not use the mineral raw materials (such as feldspar, dolomite, limestone, etc.) used in traditional ig glass, but uses high-purity chemical raw materials, such as aluminum hydroxide, calcium carbonate, magnesium carbonate, etc., By effectively reducing the content of iron oxide, there is no internal cause of self-explosion, so self-explosion of tempered insulated window panels will not occur.
(2) Designed according to the specifications to improve the anti-fall performance of insulated window panels
The current national standard "Technical Regulations for Architectural insulated window panels Application" JGJ113-2015 and the landmark "Technical Specification for Building Curtain Wall Engineering" DGJ08-56-2012 put forward clear requirements for the safe selection of curtain wall insulated window panels panels.
Based on the insulated window panels curtain wall safety assessment data of more than 42 construction projects provided by the Pudong New Area Construction Engineering Design Document Review Affairs Center, this paper summarizes and analyzes the common quality problems related to the falling off of the curtain wall panels reflected in the detailed design of the insulated window panels curtain wall, and thoroughly understands the specifications. , designed according to the specifications, to ensure the overall structural safety performance of the insulated window panels curtain wall.
a) Strengthen the quality control of insulated window panels outer sheets
According to the requirements of the National Development and Reform Commission Run [2003] No. 2116 "Administrative Regulations on Building Safety insulated window panels", the curtain wall must use safety insulated window panels. The safety insulated window panels mentioned in these regulations refers to the tempered insulated window panels, laminated insulated glass windows and other insulated glass windows products processed by the combination of tempered insulated glass windows or laminated insulated glass windows, such as safety insulating insulated glass windows, which meet the current national standards. The Shanghai landmark "Technical Specifications for Building Curtain Wall Engineering" is the first in the country to propose that if the buildings facing the street need to use insulated glass windows curtain walls, laminated insulated glass windows should be used first; for the curtain wall insulated glass windows panels of important public buildings with dense and high mobility, laminated insulated glass windows should be used.
Through the high-quality material selection before the project, the quality control of the insulated glass windows outer sheet is strengthened. The original sheet with relatively few defects is selected as the outer sheet of the insulating insulated glass windows, and moderate tempering ensures that the surface stress difference of the tempered insulated glass windows is small, the stress distribution is uniform, and the processing quality of the edge of the tempered insulated glass windows is improved.
b) Control the maximum area of insulated glass windows
Through a large number of engineering cases, it is found that the probability of self-explosion of tempered insulated glass windows with a large area is much higher than that of tempered insulated glass windows of conventional size. Therefore, on May 1, 2012, the Shanghai Landmark "Technical Specifications for Building Curtain Wall Engineering" DGJ08-56-2012, which was jointly promulgated by the Shanghai Urban and Rural Construction and Transportation Committee and the Shanghai Metal Structure Industry Association, requires: "Curtain Wall insulated glass windows The panel should be no larger than 4.5 m2, the semi-tempered insulated glass windows should be no larger than 2.5 m2, the laminated insulated window panels panel should be no larger than 9.0 m2, the tempered insulated window panels should have anti-explosion and fall-proof measures, and the semi-toughened insulated window panels should have anti-fall structural measures.”
(3) Cleverly set up buffers and rationally optimize the building shape
Due to the development of architecture, the shape of the building's facade has been enriched, and the insulated window panels curtain wall, as the outer protective structure of the building, can highlight the rich spatial levels and complex and changeable architectural effects. When designing the building shape, consideration should be given to the protection performance of the insulated window panels curtain wall from falling from high altitudes, and reasonable selection of body shape treatment methods such as retreating, overhanging, and ground floor overhead should be considered to ensure the safety of the building.
In the overall planning and design of the building, functional areas such as passage area, activity area, isolation area and buffer area should be reasonably divided, and the relationship between them should be well handled. A clear boundary must be established between the isolation area, the passage area and the activity area, safety measures for vertical protection must be established, and the passage area and activity area must not cross or overlap with the isolation area.
The setting of the setback in the curtain wall of the tower-type building has many advantages [5]. On the one hand, it enriches the shape of the building; on the other hand, it can also provide a ground-like activity place for the floor space. The retreated terrace increases the humanized use space, but at the same time forms a buffer zone to prevent the panel from falling from high altitude. On the other hand, for buildings with an overhanging shape, it is impossible to set up a reasonable buffer area due to the cramped buildings, resulting in a potential risk of fall injury.
(4) Shading and fire protection, taking into account safety
Reasonable and effective arrangement of the external shading measures of the curtain wall can improve the indoor thermal comfort environment, reduce the load of ventilation, air conditioning and heating, and improve the effect of building energy saving. However, while paying attention to the building shading effect and building appearance effect, it is also necessary to ensure the safety performance of the external shading device. Although there is no clear specification for the calculation of the structural safety of the external shading of the curtain wall, some curtain wall design units have tentatively carried out finite element calculation and analysis, and verified it through relevant simulation tests to guide specific engineering practices.
The fire performance of curtain wall has also attracted more and more attention of designers. By studying how to prevent the flame from spreading along the outer wall and roof of the curtain wall, and how to prevent the three-dimensional burning when the panel or thermal insulation material is flammable, establish a curtain wall technical index system to prevent the three-dimensional burning, and improve the design of the curtain wall fire nodes and fire partitions in the design drawing stage.
(5) Expand the scope of safety assessment and extend to the combined curtain wall
In the safety assessment, it was found that there are many forms of combined insulated window panels and stone curtain walls. Especially for heavy panels such as stone, due to the continuous degradation of the connection performance of the stone curtain wall during use, the influence of temperature changes, mechanical vibrations and various external factors, such a stress state is difficult to calculate and calculate with traditional theories. analyze.
It is suggested to expand the scope of the safety assessment, combine the structural durability analysis of the stone curtain wall, realize the full coverage of the structural safety demonstration of the building curtain wall, and improve the safety performance of the composite curtain wall as a whole.
4. Conclusion
This paper collects the design data of 42 insulated window panels curtain wall safety assessments in Pudong New Area in recent years. On the basis of summarizing the common design quality problems of curtain wall safety assessment, it further analyzes the key factors affecting the safety and use of curtain wall structure in the design process, and from the perspective of The prevention and control technology of insulated window panels curtain wall is expounded in the aspects of material internal factors, detailed design and use environment. Through the promotion of insulated window panels curtain wall structure safety demonstration and review work, the design level of the curtain wall industry has been improved as a whole, especially in the public safety and operation and maintenance of building curtain walls. Very effective control has been achieved. This work is of great significance and will continue to be Improve and develop to better serve the city.
