At present, China's economy is developing rapidly. It is precisely because of this opportunity that the construction industry in China has developed well in recent years, and the urbanization process has steadily improved, which also makes the city's land resources increasingly scarce, so high-rise buildings just meet this demand at this point and play an increasingly important role in the urbanization process. At the same time, people's requirements for fire protection of high-rise buildings are increasing day by day, so it is particularly important to strengthen the fire protection design of high-rise buildings.
1 fire characteristics of high-rise buildings
1. 1 There are many fire factors in high-rise buildings.
Modern high-rise buildings have many functions, large area and large population, and the interior decoration materials are mostly flammable materials, which are all fire hazards.
1.2 fires in high-rise buildings spread rapidly.
Many materials used in the interior decoration of high-rise buildings are flammable materials, so once there is a fire source, it is easy to ignite. Finally, the fire will spread outward along various pipes in high-rise buildings such as stairwells, tube wells, elevator shafts, exhaust pipes, cable wells and garbage passages. Once a fire breaks out, these vertical pipes in high-rise buildings will become tall chimneys and eventually form stack effect, which will greatly accelerate the flow of smoke and fire, and eventually lead to the deterioration of the fire and cause greater damage to high-rise buildings. There are many indoor pipe shafts, elevator shafts, exhaust pipes and stairwells in high-rise buildings. If there is no fire prevention design, once a fire breaks out, the fire will spread faster. Especially in libraries, research buildings, hotels, comprehensive office buildings, archives and other buildings, once a fire breaks out, it will spread rapidly.
1.3 it is difficult to evacuate people in high-rise buildings.
The vertical distance of high-rise buildings is relatively high and there are many floors. When there is a fire in the building, it takes a long time to evacuate the people on the floor. In high-rise buildings, elevators can't be used in case of fire, so people can only rely on stairs for evacuation. High-rise buildings have a large population. When there is a fire in a building, a lot of smoke will rush into the stairwell, which will seriously affect the evacuation of people.
1.4 fire fighting and rescue of high-rise buildings is very difficult.
Due to the structural characteristics of high-rise buildings, it is difficult to rescue when there is a fire in high-rise buildings. According to the current situation in China, most high-rise buildings in China use glass curtain walls. In case of fire, the glass curtain wall is easily broken, which will cause harm to people downstairs, and the debris will even affect water supply equipment or fire engines. The high-rise building is high, and the spraying degree of fire fighting equipment can not meet the requirements of building height, so it is very difficult to rescue.
2 Key points of fire protection design for high-rise buildings
2. 1 The fire partition and fire spacing of high-rise buildings should be designed reasonably.
In the fire protection design of high-rise buildings, it is necessary to consider the fire zone and fire spacing. The so-called fire zone mainly refers to the space separated by fire separation measures, which can properly control its fire trend within a certain range and time, slow down the spread of fire, provide rescue time for firefighters and provide escape time for evacuees. In the design of high-rise buildings, there are generally two fire zones: horizontal zone and vertical zone. In high-rise buildings, horizontal zoning is mainly realized by reinforced concrete floor, firewall and fire shutter. The vertical fire protection zone is divided by windowsill wall, fire-resistant floor and other structures.
In high-rise buildings, the fire protection design of traffic passages is necessary. Vertical fire partition refers to the space vertically separated by fire separation facilities such as floors and sill walls. Horizontal fire partition refers to the space horizontally separated by fire shutter, fire door and firewall. Only safety evacuation doors can be installed on the firewall, and other windows, doors and holes cannot be installed. In addition, the firewall does not allow flammable gas pipelines to pass through.
When the indoor area of a high-rise building is larger than that of the fire partition, it is necessary to set fire shutter in its proper position. The fire shutter will only fall automatically in case of fire, and will not affect the usual space. When designing high-rise buildings, we should consider the surrounding environment and keep a certain distance between two adjacent buildings. This is mainly for the purpose that when a fire breaks out in a building, the surrounding buildings will not be affected and people can evacuate safely. According to relevant codes, the protective distance between two high-rise buildings should be greater than 13m, and the distance between the main building and the podium should be greater than 9m.
2.2 Reasonable design of safety evacuation stairs
Stairs are the main passages for evacuating people in building fires. When there is a fire in a high-rise building, elevators and escalators cannot be used. When designing stairs in high-rise buildings, it is necessary to design stairs as outdoor stairs, smoke-proof stairs and closed stairs. This design can not only prevent the fire from spreading, but also ensure the safety of evacuation. For high-rise buildings, the number and location of stairs are also required. The number of stairs in each fire zone shall be no less than two, and their positions shall be dispersed, mainly to avoid crowding in case of fire.
2.3 Design the smoke exhaust system of high-rise buildings.
When a high-rise building is on fire, there are two main forms of injury to people: flame injury and smoke injury. Both forms of injury can lead to death. In order to reduce the harm of fire smoke to human body, it is necessary to design the smoke exhaust system of high-rise buildings when designing high-rise buildings. When designing the smoke exhaust system of a high-rise building, it is necessary to divide the building into smoke-proof areas first. Smoke-proof areas and fire-proof areas should be separated and not overlapped, and the area of each smoke-proof area should be less than 500m2.
Smoke-proof partitions can be divided by smoke-proof vertical walls and partitions, and each smoke-proof partition needs to be provided with smoke outlets, which are generally arranged in the smoke-proof center. In addition to the smoke outlet, the smoke exhaust system also needs to design smoke exhaust pipes. The design requirements of the smoke exhaust duct are very strict, its installation must be firm and the materials used must be fire-resistant, and the design of the smoke exhaust duct cannot overlap with the fire protection zone.
2.4 Reasonable design of fire elevators and refuge floors
In order to ensure the safety of fire control work, in case of fire, the power supply should be turned off first. At the same time, the service elevator must be stopped. In this case, the use of fire elevators plays a key role. In this way, fire-fighting equipment and firefighters can arrive at the scene in time, and the wounded can be sent to the hospital as quickly as possible. It is worth mentioning that the fire elevator shaft must be independent, and equipment should be installed in different fire areas, so as to cover more areas and ensure the efficiency of fire control work. In addition, the number of fire elevators should be set according to the specific floor conditions, and drainage measures should be taken at the bottom of the elevator to prevent the elevator from running too much. In high-rise buildings, due to the large number of people, it is difficult to ensure the safety of all personnel in case of fire.
There are also some unstable factors, such as unexpected congestion. These problems warn relevant departments to set up temporary shelters in fire protection design to ensure the safety of personnel in a short time. The setting of refuge floor has many advantages, which can not only shorten the distance between people, but also help residents reach the safety zone in time and reduce the pressure of fire control work. Theoretically, the distance between two refuge floors must be controlled within 15 floor, which is beneficial to work. The evacuation stairs also have special requirements, and must be set on the refuge floor for conversion, which is the last direct access to the ground. At the exit of the fire elevator and beside the special fire telephone, a refuge floor should be set up and equipped with comprehensive fire fighting tools. The requirements for the decoration materials of the refuge floor are also quite strict. Because it is to deal with fire problems, it is necessary to avoid using flammable materials.
3 Conclusion
The fire in high-rise buildings is a serious problem. To do a good job in fire protection design of high-rise buildings, we must first understand the fire factors and characteristics of high-rise buildings. Then according to these factors and characteristics, the fire prevention design of high-rise buildings is carried out to eliminate the possibility of fire from the source.
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