Tall buildings are obviously made of concrete, why does the whole building burn after the fire? What's the problem? I don't know if you have ever heard such a news, that is, on March 9 this year, there was a fire in an office building with 26 floors in Shijiazhuang, and that scene was like a science fiction movie, with thick smoke and flames. Everyone must feel sorry for this, but also a question will come to mind, the tall building is made of reinforced concrete, why does it burn the entire building after the fire?
The above-mentioned Fire of Shijiazhuang high-rise office building is because it first burned up from the first floor of this building, and then in a short period of time, the fire climbed to the 26th floor of the tallest building at a very fast speed, and today's buildings are basically made of reinforced concrete materials, and here we need to popularize it, which is divided into building construction in China. We take flammability as a reference, and its building construction can be roughly divided into three categories, which are non-combustible, flame retardant and flammable.
Non-combustible building construction can be understood literally, that is, when this type of material is burned by fire, or does not catch fire at all in an extremely high temperature environment, then what are the common non-combustible building constructions? Materials such as steel, concrete and brick are non-combustible building construction. The construction of flame retardancy means that it is difficult to catch fire in the air or in a high temperature condition, but it does not mean that it will not catch fire, as long as the fire source is separated, the flame that is originally burning will slowly stop. Flame retardant construction can also be seen in real life, including asphalt concrete after flame retardant operation of cement and plastic. Finally, there is the combustible building construction, which is undoubtedly a substance that is easily burned when the air is burned and is easily burned at high temperatures, and even if measures are taken to isolate the source of fire, these structures can still remain burning, such as wood, bamboo and other materials can obviously be classified as this category. Knowing this knowledge, we can know that it is difficult for our houses to burn up, so what is the problem?
Although the materials for building houses are extremely difficult to burn up, but it does not mean that anything in the house is lowly combustible, the rooms in the house are not used to live or to work, so many equipment and items will be placed, including insulation materials pasted on the external wall, decorative materials for the interior decoration of the house, and some furniture and daily necessities, etc. Most of these things will be easily burned, the flammability is extremely high, and for those with a relatively high base, some debris is difficult to move down and move, I like to pile up in the corridors, but these are all the food of the fire. And China's population base is so large, the number of houses has also increased, the houses are not only high floors but also very dense, people come and go, the probability of fire is very large.
In addition, what other reasons are the fire that spread throughout the building? This situation is more likely to occur in the older residential areas, for those old houses and fire fighting equipment is not complete, even if there is a fire, there is no way to extinguish the fire, so the fire is more arrogant in the absence of enemies, directly engulfing the entire building. It's also related to the weather, especially in the spring and winter, where the number of fires can be high. Fire favorite is that in a windy but very dry environment, in the building will be equipped with elevators, mainly to enable residents and office staff to bring more convenience, which will also have a hidden danger, that is, when the fire occurs, the elevator to the fire to play a role in aid, which involves a principle - chimney effect.
What is the chimney effect? The chimney effect is that the air inside the house rises or falls along the space with a vertical slope, and the purpose is to strengthen the convection of air inside and outside the building, because these air can keep the upper and lower parts of the building smooth in the process of rising or falling. And we all know that fire cannot burn in a vacuum, it is easy to burn in the air. So when there is a fire in a high-rise building, it is easy to have the help of the objects in the building, so that the flame will burn the entire building. But don't worry too much, for those who live in high-rise buildings, the fire fighting facilities in the high-rise buildings are very well equipped and special fire passages are arranged, such as the automatic sprinklers that we can see when we look up, and there are shelter floors in the high-rise buildings, which can help everyone escape in the event of a fire emergency. What else can we do in the event of a real fire?