Key Factors Affecting the Safety and Application of IGU Glass Curtain Wall
Key Factors Affecting the Safety and Application of IGU Glass Curtain Wall
my country's igu glass curtain wall industry started in 1983 and entered a period of rapid development in the 1990s. Because of its simple, luxurious and modern appearance, the igu glass curtain wall has a good decorative effect [1-2]. In Shanghai, it is because of its light weight, which is equivalent to 1/12 of the brick wall and 1/10 of the concrete wall; the construction period is short, saving 2/3 of the construction period of the general building wall, and the preparation favored.
The Shanghai "Friendship Building" located on Yan'an East Road was completed in 1984, the first IGU Glass curtain wall in Shanghai. By the end of 2016, there were about 12,000 IGU Glass curtain wall buildings in Shanghai, which has become the city with the largest number of IGU Glass curtain wall buildings in my country. The total curtain wall area accounts for about 20% of the country's total, and most of them exist in densely populated CBD areas. However, in this short period of 30 years, my country's curtain wall industry has completed the 150-year development history of foreign building curtain walls. Some investigation and research data show  that these existing IGU Glass curtain wall buildings have great potential safety hazards, mainly manifested in the self-explosion of tempered IGU Glass, the falling off of panels, the falling of opening fans, the aging of structural adhesives, the failure of connectors, and the lack of hardware. multiple questions.
The Shanghai Government Decree No. 77 "Administrative Measures for Building IGU Glass Curtain Walls in Shanghai" promulgated and implemented in 2012 clearly stipulates: "For construction projects using IGU Glass curtain walls, the construction unit shall prepare a IGU Glass curtain wall structural safety report at the stage of preliminary design documents, and submit The construction administrative department organizes expert demonstrations (Article 9)"; "The construction unit shall submit a structural safety demonstration report, a light reflection environmental impact technical assessment report and an expert demonstration report when applying for the review of construction drawing design documents (Article 10) ".
Hu Jian Jiao (2012) No. 100 Document "Notice on the Implementation of the Safety Demonstration of Building insulated glass unit Curtain Wall Structure", which was issued in the same period, clearly stipulates: "In the administrative area of this city, new construction, reconstruction, expansion projects and facade renovation projects will be carried out. Construction projects using insulated glass unit curtain walls shall implement the safety demonstration of building insulated glass unit curtain wall structure (Article 1) in accordance with the provisions of the "Administrative Measures for Building insulated glass unit Curtain Walls in Shanghai"; The application form for building insulated glass unit curtain wall structure safety demonstration, the insulated glass unit curtain wall structure safety report, the insulated glass unit curtain wall structure calculation book, the Shanghai construction project report form, and the approval opinions of the planning department (Article 4) shall be submitted. The above-mentioned laws and regulations have been implemented for nearly five years. During the implementation of insulated glass unit curtain wall structure safety demonstration (hereinafter referred to as "safety assessment"), management departments at all levels, construction units, design units, and curtain wall enterprises have encountered many problems. On the basis of summarizing and sorting out the common design quality problems of curtain wall safety assessment in the first stage, this paper intends to further analyze the key factors affecting the safety and use of curtain wall structure in the design process from the perspective of ensuring urban public safety, and continuously improve the management of architectural insulated glass unit curtain wall. The supporting measures of the method, and the prevention and control technology of the common problems in the design quality of the building curtain wall are expounded from the two aspects of the internal factors of the material and the construction environment.
2. Common Design Quality Problems
In the first stage, by summarizing and sorting out the common design quality problems in the curtain wall safety assessment, we carried out the safety assessment data according to the six perspectives of "design description, material selection, safety design, structural drawing, structural calculation book, and others". Summarize, use the method of mathematical statistics for classification and summarization
With the strong support of the Science and Technology Committee of the Shanghai Pudong New Area Construction and International Relations Commission and the Pudong New Area Construction Engineering Design Document Review Affairs Center, based on the collected 42 insulated glass unit curtain wall safety assessment design data, further focused on refining the curtain wall structural safety and impact in the design process. The key factors used are summarized and improved in the form of literature search, expert meetings, questionnaires and other forms, and there are five main aspects of common design quality problems:
(2) The detailed structural design is not in place, and the structural calculation of the connection part is missing;
(3) The decorative strips (shading strips) of the façade are designed and used boldly before the lack of reasonable verification;
(4) Insufficient fire rating of building materials, improper setting of fire compartments, etc.;
(5) There are many problems with the stone curtain wall in the composite curtain wall.
3. Prevention and control technology for common problems in design quality
According to the different degrees of influence of common design quality problems found in the above-mentioned tempered glass wall curtain wall safety assessment, in addition to meeting the requirements of the mandatory provisions of national, industrial and local construction standards, this paper summarizes and proposes the structural design of tempered glass wall curtain wall from two aspects: internal nature and external use. key factors, and carry out research in a targeted manner, and propose relevant prevention and control technologies.
(1) Optimizing raw materials to essentially solve the self-explosion of curtain wall tempered glass wall
According to the results of a sampling survey on the quality and safety of curtain walls of 96 buildings in use in 10 cities in Beijing, Shanghai, Tianjin, Chongqing, Xi'an, Wuhan, Shenzhen, Harbin, Xiamen and Wenzhou by the Curtain Wall Engineering Committee of China Building Decoration Association, the existing There are hidden safety hazards in the curtain wall, which can be preliminarily identified as 47 panels with self-explosion of tempered tempered glass wall, and 9 curtain wall projects with important hidden dangers, accounting for 9.38% of the total number of investigation projects. If the self-explosion factor of tempered tempered glass wall is removed, the proportion drops to 2.3%.
tempered glass wall panels are the most commonly used materials for curtain walls. Since tempered glass wall is mixed with nickel sulfide crystals during the production process, NiS (nickel sulfide) has a phase transition process at 379 ° C, from high temperature α-NiS crystal system to low temperature. In the state of β-NiS crystal system, the volume expansion is 2%~4%, and the surface is rough. If these impurities are in the tensile stress region of tempered tempered glass wall, the volume expansion may cause bursting. The new research shows that the expansion of the elemental silicon crystal particles in the tempered glass wall can also cause the tempered glass wall to crack. The expansion coefficient of elemental silicon particles is only half of that of glass, but its hardness is greater than that of glass. Since some elemental silicon particles are dispersed in the glass, when the temperature drops, the tangential stress of the glass around the elemental silicon particles increases. When the stress is too large, local tensile cracks are caused, and the whole is broken.