Fire protection design of steel structure building

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Discussion on fire protection design of steel structure buildings

first of all, let's analyze the disaster characteristics of aluminum alloy profile parts, aluminum alloy stamping parts and aluminum alloy casting parts used in high-end pure electric car running in cooperation with great wall Huaguan. The beams, columns and roof trusses of steel structure buildings are the framework of the building, and their safety is directly related to the safety of the whole building. Most of them use steel. Although steel is non combustible, its fire resistance is very poor. With the change of temperature, its mechanical index will change greatly, and the bearing capacity and balance stability of glass balls gb18428 (2) for automatic fire extinguishing system will decrease significantly with the increase of temperature. When the temperature of steel structure reaches 350 ℃, 500 ℃ and 600 ℃, its strength decreases by 1/3, 1/2 and 2/3 respectively, and its internal stress will also change under high temperature conditions, resulting in problems in the load-bearing system of steel structure. According to theoretical calculation, under full load, the critical temperature at which the steel structure loses equilibrium stability is 500 ℃, and the general fire site temperature is about 800 ℃ - 1000 ℃. Under such high temperature conditions, Without any protection, the steel structure will soon undergo plastic deformation and collapse within about 15 minutes. On september11,2002, the world trade building in New York collapsed in a terrorist attack, resulting in the innocent deaths of more than 300 firefighters. After the aircraft hit the building with full load of fuel, the protective layer of the bearing steel structure cylinder of the building was damaged. Under the strong high temperature, the bearing strength of the steel structure cylinder decreased rapidly. Just 20 minutes later, the world's most famous building disappeared in our face. In 2003, a huge fire broke out in the steel structure workshop of Zhengda food factory in Qingdao, China, causing a large area of the workshop to collapse, and many workers were buried in a sea of fire; In 1972, a fire broke out in Tianjin gymnasium, causing the roof to collapse and causing huge casualties. These numerous fire cases have exposed that the fatal weakness of using low-cost technology to improve the performance of plastic packaging materials in steel structure buildings is the extremely poor fire resistance, which puts forward a new topic for our architectural designers, how to do a good job in the fire protection design of steel structure buildings, so that the steel structure buildings can better serve our economic construction

how to do a good job in the fire protection design of steel structure buildings? I think the following three aspects should be achieved, but the more important is the nine inspection items:

first, the fire resistance rating of the building should be reasonably determined according to the fire risk and importance of the building. Due to the different functions and importance of various buildings, there are differences in fire risk. During the design, we should determine the fire risk of the building according to the building requirements provided by the owner, the code for fire protection design of buildings and the code for fire protection design of high rise civil buildings, and then determine the fire resistance rating of the building according to the fire risk. For example, a 60 meter high complex building is a class I high-rise building according to the code for fire protection design of high rise civil buildings, Its fire resistance rating shall be class I, and the fire resistance limits of its beams, columns and roof load-bearing members shall not be less than 2 hours, 3 hours and 1.5 hours respectively. If we do not correctly verify the fire resistance rating in the design, the determined fire resistance rating is too high or too low, which will cause our design error, waste if it is too high, and insecurity if it is too low

II. Appropriate fire protection methods for steel structures shall be selected during design. At present, there are three main protection methods for steel structures in China: spraying method, cladding method and water spray cooling method. They all improve the fire resistance of steel structures through certain technical means. Specifically, the spraying method is to apply a layer of fireproof coating on the surface of steel structure to form a protective film, so as to improve the fire resistance limit of building components. It can be divided into thick and thin types, and the fire resistance limit of coatings with different thickness is different; The cladding method is to use bricks, concrete, calcium silicate board and other materials to wrap the steel structure, so as to form a protective layer and improve the fire resistance limit of the components; The water spray cooling method is to arrange an automatic sprinkler system on the upper part of the steel structure. In case of a fire, start the sprinkler to form a continuous water film on the surface of the steel structure to achieve the protective effect. During the design, we should select the most appropriate fire protection method according to the requirements of different buildings on the fire resistance limit of components and through scientific comparison, so as to meet the economic and safety requirements

III. personnel evacuation shall be fully considered in the design of steel structure buildings. Due to the weakness of the steel structure building itself, we should fully consider the factors of personnel evacuation in the design, take the personnel density index and the characteristics of the steel structure building into consideration, strengthen the design requirements for the safe evacuation route, evacuation distance and evacuation width, ensure that the evacuation time is less than the fire resistance limit of the building components, ensure that the personnel can escape safely in case of fire, and avoid the occurrence of mass casualties

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