With the improvement of economic and social development and the deepening of urbanization, the land for urban residential construction in various places is becoming increasingly tight, and land prices are getting higher and higher. Therefore, the construction of urban residential buildings is gradually developing towards the sky, and high-rise buildings There are more and more residential buildings. According to surveys, since 2003, the proportion of high-rise residential buildings in newly developed residential communities in Yangzhou City, where the author is located, has exceeded 30%, and there is a trend of further increase. However, under the current circumstances, fire prevention awareness and the popularization of fire prevention technology during the construction of high-rise residential buildings are still at a low level, and there are many congenital hidden dangers. Here, the author makes some simple analysis and research on how to properly control the source of building fire protection design, prevent the occurrence of fires in high-rise residential buildings, and ensure the safety of people's lives and property.
1. Fire hazard characteristics and fire prevention principles of high-rise residential buildings
Due to the large number of physical partition walls inside the building, high-rise residential buildings have better functions of preventing the spread of fire both vertically and horizontally. Well, in addition, the interior decoration of this type of building is relatively simple and there are few people inside. There are not many domestic fire cases, so its fire protection function is often ignored intentionally or unintentionally. There are some problems in the construction from design, construction to management. Insufficient ideological and technical preparation for the degree. This shortcoming is mainly reflected in the non-compliance and implementation of the "Fire Protection Code for Design of High-Rise Civil Buildings" (hereinafter referred to as the "High-Rise Code") by the construction, design and construction units of high-rise residential buildings; it is also reflected in our public security and fire department's supervision of high-rise buildings. Omissions and dereliction of duty in the publicity, education, supervision and management of fire prevention work in residential buildings. This deficiency forms a sharp contradiction with the ever-changing and extraordinary speed of urban construction, which directly leads to the occurrence of congenital fire hazards. Generally speaking, three main principles should be considered for residential building fire protection: first, the design ensures that the fire hazard in the building is reduced to the lowest point; second, the fire alarm is known as quickly as possible and eliminated in the most timely manner by relying on fixed fire protection facilities; The third is to ensure that the building structure has the prescribed fire resistance strength to facilitate the effective and safe evacuation of the occupants in the building within the corresponding time. Based on the above principles, building fire protection design can be divided into two parts: active fire protection system and passive fire protection system. The so-called active fire protection system is composed of automatically (or manually) controlled alarm, fire extinguishing, smoke prevention and exhaust, fire protection electricity, fire water supply and other equipment systems. Its basic function is to detect and extinguish fires early. The passive fire protection system of the building mainly consists of non-combustible and refractory decoration materials; fire doors, fire shutters, fire ceilings, steel and concrete structural fire walls, cable fire pipes (wells), ventilation and smoke pipe wells, and smoke barrier vertical walls , pipe wall sealing, etc., its function is to use appropriate building materials and components to divide a large space into several small spaces, and during the process of fire occurrence and spread, the fire can be controlled within a small range as much as possible , and ensure that the whole or part of the building structure does not collapse within the time interval specified in the design. Under the current national conditions of our country, the design of passive fire protection systems is more common, reliable, durable and economical.
2. Key points of fire prevention countermeasures that should be grasped in the design of passive fire protection systems for high-rise residential buildings
(1) Safe evacuation
Regarding the setting of evacuation stairs, "High-rise Residential Buildings" Regulations require: There should be no less than two safety exits in each fire protection zone of a high-rise building, only if it is 18 floors or below, each floor should not exceed 8 households, the building area should not exceed 650 square meters, and there should be a smoke-proof staircase. Only tower residences with rooms and fire elevators can have only one safety exit. In some designs, only one staircase is provided where there should be two stairs according to regulations, leaving the building with inherent fire evacuation risks. The "High-rise Regulations" also stipulates that "the evacuation stairs of each unit of a unit-type residential building should lead to the roof." This is considered from the two-way perspective of evacuation and smoke prevention in the event of a fire in a high-rise residential building. However, we often see that some In high-rise residential buildings, the entire roof is made into a multi-sided slope shape or a four-sided slope shape, making it impossible for stairs to reach the roof. Such houses lose the temporary refuge function of the roof space, exacerbating the difficulty of rescue and disaster losses in case of fire.
The smoke-proof stairwell and its front room in a residential building, the front room of the fire elevator room or the shared front room are the most important evacuation routes in case of fire. According to the experience of developed countries in the world and my country's national conditions, natural smoke exhaust is recognized as an economical, simple and easy-to-operate method of smoke exhaust. Therefore, it should be used first. Stairwells are required to have a certain window area and smoke exhaust. The window should be located above the wall and must be easy to open.
However, it is sometimes difficult to ensure fire safety by relying solely on natural smoke exhaust. Therefore, closed buildings, elevator rooms, and mechanical smoke exhaust and ventilation systems must be installed as needed and required.
The "High-Level Regulations" stipulate that high-rise residential fire elevators should have a front room of no less than 4.5 square meters. If the front room is shared with a fire and smoke stairwell, its area should be no less than 6 square meters. However, many architectural designs do not pay attention to this regulation. In order to save traffic area, there is only one elevator in a building; some buildings do not have an elevator front room, or the elevator front room is open and has no fire door. Once a fire occurs, it cannot be prevented and discharged. Smoke not only makes it difficult to control a fire, but also makes fire fighting operations difficult.
(2) Fire protection zoning
Fire protection zoning includes two types: horizontal and vertical. Horizontal fire protection zoning means that when the floor area of ??a residential building exceeds a certain scale, fire walls, fire doors, fire shutters, etc. are used to separate each floor into two or several fire protection zones in the horizontal direction. The "High Regulations" require that each fire protection zone of high-end residential buildings and ordinary residential buildings above 19 floors should be controlled within 1,000 square meters; and that each fire protection zone of ordinary residential buildings from 10 to 18 floors should be controlled within 1,500 square meters. The concept of vertical fire protection zoning refers to the fire protection separation between upper and lower floors by floor slabs and other components with a fire resistance rating of not less than 1.5 hours or 1 hour respectively. Generally speaking, the vertical fire protection zone is one zone for each floor, or one zone for two to three floors. For units or houses, since the reinforced concrete floors between the upper and lower floors can completely block the upward spread of fire, the focus of vertical fire protection zoning is to protect the garbage chute, equipment wells, air conditioning ducts and air conditioning ducts inside the building. Implement fire prevention barriers in buildings and elevator rooms to minimize the spread of fire and control the fire burning area.
(3) Fire prevention of pipe wells
The "High Regulations" stipulate that vertical pipes such as cable wells, pipe wells, flue ducts, exhaust ducts, and garbage ducts should be installed separately. Set up independently, the shaft wall should be a non-combustible body with a fire resistance limit of not less than 1 hour; the inspection door on the shaft wall should be a Class C fire door. The "High-rise Regulations" also stipulates that for high-rise buildings with a building height not exceeding 100 meters, The cable wells and pipe wells should be separated by non-combustible materials equivalent to the fire resistance limit of the floor every 2-3 floors. For high-rise buildings with a building height exceeding 100m, the fire resistance of each floor should be equivalent to the fire resistance limit of the floor. Non-combustible materials are used as fire separation. The gaps between cable wells and pipe wells connected to rooms, walkways, etc. can be filled and densely filled with non-combustible materials such as cement mortar boards and steel plates.
(4) Fire protection of glass curtain walls
In order to pursue the architectural appearance effect, some high-end apartments and residences use glass curtain walls, which is quite controversial in the domestic and foreign construction circles (Japan, Germany and other countries have expressly prohibited its use). Part of the reason is that not only does the glass curtain wall become a way for fire to spread due to wind pressure, but also after a fire, the curtain wall often reaches the fire resistance limit and falls downwards before the evacuation of people is completed, seriously affecting the evacuation behavior. . When a fire occurs, flames and thick smoke will also spread rapidly along the gap between the glass curtain wall and the main structure, causing increased fire losses. At present, there are many shortcomings in the design and construction of many glass curtain walls, and management is out of control. Many curtain walls only consider fire prevention and sound insulation methods for the 5-10cm gap between the curtain wall and the floor slab, and the curtain wall and the fire wall. However, the materials used are rubber, foam plastics, wooden plywood, etc., which are far from the standard requirements and need to be corrected as soon as possible.
3. Key points of fire prevention countermeasures that should be grasped in the design of active fire protection systems for high-rise residential buildings
(1) Fire water supply design
According to the relevant provisions of the "High-rise Regulations" According to regulations, the fire water supply system consists of fire water sources, water tanks (roof and zone pressure reduction water tanks), water pumps, control rooms, fire pipe networks and fire hydrants. More than 80% of fire cases that failed to put out fires were due to insufficient fire water supply. Therefore, it is very important to ensure the water supply needs when extinguishing high-rise residential buildings, especially the fire water source. The fire protection design of high-rise residential buildings should be based on self-rescue of the indoor fire water supply system as the main fire extinguishing method. Therefore, regional centralized or temporary high-pressure fire water supply systems should be used in high-rise residential buildings.
The fire water tanks installed in high-rise residences should meet the water pressure and water volume requirements for fire extinguishing at the most unfavorable point in the room. Otherwise, high-pressure water supply, pressure-stabilizing pumps and other pressurizing facilities should be installed. The capacity of the water tank should be based on the building plan type (corridor type, The outdoor fire water supply pipe network of high-rise residential buildings should be arranged in a ring shape, and the fire hydrants should be exposed as much as possible to facilitate fire trucks to draw water. The number of installations should comply with regulations, and the water supply pressure should not be low. at 0.1MPa. The indoor fire water supply system of high-rise residences should be set up separately from the domestic water supply system, and the indoor fire water supply pipes should also be arranged in a ring. There should be no less than two water inlet pipes and introduction pipes of regional high-pressure or temporary high-pressure water supply systems. The fire pump is the heart of the fire water supply system. Its working performance, quantity, installation and opening method must ensure the timely and reliable operation of the fire pump. In the same community, the fire pool and fire pump room can be used independently, and the indoor fire hydrant water supply system The automatic sprinkler system of high-end residential buildings should also be equipped with water pump adapters. The number and water flow rate must comply with regulations. The distance from outdoor fire hydrants or fire pools should be 15-40 meters. As for indoor fire hydrants, the "High Regulations" It is required to be installed in obvious locations such as residential walkways, stairwells, and front rooms of fire elevators. The key points are to facilitate access and ensure that two effective water columns arrive at the same time. However, current residential building designs often do not consider the reserved location of fire hydrant boxes.
(2) Smoke prevention and exhaust design
More than 60% of the deaths in high-rise building fires are due to smoke, so smoke prevention and exhaust design is essential in building fire protection In this link, smoke prevention and exhaust methods are divided into two categories. One is the natural way, that is, the smoke is discharged through external windows, balconies and shafts. The second is the mechanical method, which is divided into two types: pressurized smoke prevention and decompression smoke exhaust. The effect of natural methods is difficult to guarantee because they are easily affected by wind direction and region. Therefore, the state stipulates that natural methods should not be used to exhaust smoke when residential buildings exceed 100 meters. It is a very effective way to set up a patio in a residential building so that smoke-proof stairwells, fire elevator front rooms, etc. located inside can open windows to naturally exhaust smoke. At the same time, the shaft can also be used in stairwells on the underground floor to provide daily lighting. , ventilation and smoke exhaust are very beneficial in case of fire. For mechanical methods, pressurized smoke prevention is mainly used in smoke-proof stairwells and shared front rooms, while decompression smoke exhaust is mainly used in some enclosed spaces, atriums, Basements and evacuation walkways, etc.
(3) Electrical fire protection design
The electrical fire protection design of high-rise residential buildings mainly has two aspects of significance. One is to enhance electrical safety in the sense of passive fire protection and avoid wiring due to Long-term overload operation and severe insulation aging may cause electrical fires. We even need to consider the prevention of electrical fires caused by sudden disasters such as earthquakes and lightning strikes. The second is how to ensure fire power and distribution in the sense of active fire prevention. How to ensure that Fire emergency lighting, evacuation signs and automatic fire alarm and fire control. There are three points that need to be emphasized here:
(1) Double-circuit power supply should be implemented for fire pumps and elevators in high-rise residential areas, especially residential buildings with more than 12 floors, including the use of self-provided generator sets and batteries. As a fire backup power supply.
(2) Fire-fighting electrical equipment in high-rise residential buildings should adopt an independent power supply circuit to ensure that when a fire occurs, the fire-fighting main control room, fire elevators, fire water pumps, emergency lighting, and smoke prevention and exhaust systems have fire-fighting power. And the switching method of the two power supplies of the above-mentioned fire-fighting electrical equipment, the switching point and the start-up time of the self-prepared power supply must comply with the provisions of the "High-Level Regulations".
(3) Fire examples have proven that the setting of accident lights and evacuation signs has a great impact on the severity of casualties, and is pertinent and relevant to the current situation of high-rise residential living and the lack of urban firefighting maneuvers and climbing capabilities. Necessity must also be paid attention to and strengthened.
(4) Fire-fighting equipment
As we all know, fire extinguishers are important fire-fighting equipment for extinguishing initial fires. They are light, flexible, movable, and can be operated with a little training. Practice has proved that fire extinguishers are the most effective fire-fighting equipment. The ideal first-line fire extinguishing tool during the process. However, during fire inspections, it was discovered that many high-rise residential apartments do not have fire extinguishers installed as required or the number of fire extinguishers installed is insufficient. The "Building Fire Extinguisher Configuration Design Code" clearly stipulates that there should be no less than two fire extinguishers in a fire extinguisher configuration place. This is because in When actually putting out a fire, if two people can hold fire extinguishers at the same time and work together to put out the fire, it is necessary to quickly and effectively put out the initial fire, especially the larger fire. In addition, all mobile fire-extinguishing equipment should be stored, updated and maintained according to regulations to ensure their normal use.
IV. Conclusion
The emergence of fire hazards in high-rise residential buildings has many deep-seated social and economic reasons. However, designers have little awareness of the concept of fire protection in architectural design. The construction unit's intrusiveness and unreasonable interference, as well as the lax control of the city's fire protection and construction departments, are important root causes. Architectural designers must first be familiar with and strictly master the building fire protection design specifications, study and research carefully, and must not follow the old tradition or make careless omissions. To establish the dominant position of designers in the overall fire protection planning, they must not only solve the fire protection problems in high-rise building planning, but also undertake the modification and control tasks during the fire protection review and implementation process. At the same time, strict fire law enforcement penalties must be imposed on construction units that violate regulations and interfere with fire protection designs. Fire prevention in high-rise residential buildings is a century-old plan and must be prevented before "burning" occurs. Don't make big mistakes for the sake of temporary immediate benefits. Finally, the strict control of the fire protection construction management department is the key to ensuring residential fire safety. It must also enforce the law and be meticulous. Only in this way can the occurrence of residential fire accidents be reduced and the safety of national construction and people's lives and property be guaranteed.
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