Technical analysis of building fire protection design?

High-rise buildings refer to buildings with ten floors or more (including buildings with commercial service outlets on the first floor). The middle and upper floors of high-rise buildings have wide vision and good lighting and ventilation; The building is tall and straight, and the facade shape and color of the building are generally fashionable, with a sense of the times and the city; High floor area ratio, saving land resources and other advantages, so in urban construction, high-rise buildings are increasing year by year. However, there are also some problems in high-rise buildings, such as high fire prevention requirements and great difficulty in extinguishing fires. To solve these problems, we must start from the stage of architectural design and construction and the stage of fire protection system design. Correctly handling the fire protection problem in architectural design is directly related to the safety of people's lives and property.

1 Frequently asked questions in fire protection design

At present, some designers and constructors do not have a thorough and comprehensive understanding of national codes and standards, which leads to some defects in the fire protection design and construction of evacuation places such as evacuation walkways, evacuation stairwells, forerooms, shared forerooms and refuge floors, and leads to some obvious fire hazards in the design and construction of this project. Specifically, for example:

1, selection of fire pressure pump

The selection of fire booster pump must meet the needs of flow and lift. Through calculation, the fire-fighting flow is 20L/s, and the required lift of the fire-fighting pump is 105m. When choosing a pump, it is difficult to choose a pump that meets the design requirements, and the head of the selected pump exceeds the required pressure. In order to solve the problem of excessive pressure, the impeller of the cutting pump is to meet the needs of lift.

2, the use of double valve and double outlet hydrant and hydrant spacing.

When high-rise buildings are widely built in China, single-valve and double-outlet fire hydrants came into being. Although there is a blind cover on the bolt mouth, there are still many disadvantages in practical use. But at that time, they were all regarded as "treasures", vying for adoption, and some people vigorously promoted them. That's understandable. Up to now, double-valve and double-outlet hydrants have been produced, which completely overcomes the shortcomings of single-valve and double-outlet hydrants. All major design institutes in China have also adopted it. In recent years, some buildings in Nanjing have also agreed to use them when they are inspected by the municipal authorities, and it is suggested that some occasions be changed to double-valve and double-outlet fire hydrants. For the high-rise tower residence with 18 floor and below, with no more than 8 households on each floor and a construction area of no more than 650m2, when there is no walkway or the length of the walkway is less than 5m, and two water columns can reach any part of the same floor at the same time, a double-valve double-outlet hydrant and a fire riser can be set in the front room of the fire elevator.

3. Fire pump pipeline pressure relief device

At the initial stage of fire pump operation, the municipal pipeline pressure is often unstable and the lift is too large, which will cause high pressure in the pipeline network. Therefore, it is necessary to set a pressure relief valve on the outlet pipe of the fire pump. When the pipe network pressure exceeds the set working pressure (30), the pressure relief valve will automatically open to release water and pressure to prevent the pipe network from overpressure. With the increase of fire water consumption, the pressure of the pipe network gradually decreases, and when it falls to the pressure set value of the pressure relief valve, the pressure relief valve automatically closes.

2 high-rise building fire protection system design technology

1, fire pool

Because the "High Code" strictly stipulates the conditions for not setting fire-fighting pools, taking Nanjing as an example, basically all high-rise buildings have fire-fighting pools, so that the whole city has large and small fire-fighting pools, which not only occupies a lot of building area (the average area of each pool exceeds 100 square meter), but also increases investment, and also causes water pollution due to long-term non-use.

In view of the relatively perfect fire prevention measures in high-rise buildings, the fire is not easy to spread, and the probability of simultaneous fire in buildings is low, the following solutions are adopted: First, to enhance the overall planning awareness, it is necessary to build adjacent buildings of fire-fighting pools, with * * * building fire-fighting pools for * *, and other * * * being jointly funded and managed by the buildings where the pools are located; Second, it can be demonstrated that outdoor fire hydrants and water pump connectors are evenly arranged in reasonable positions of the building, and the water storage capacity of roof water tanks is appropriately increased. In case of fire, the high-power fire truck will take water from the fire hydrant and use the water pump adapter to pressurize the water supply; Third, set up a fire-fighting pressurized pump room in the center of the building to take water directly from the municipal pipe network (suitable for the municipal pipe network to allow the fire pump to pump water directly from the pipe network); Fourthly, outdoor reservoirs designed by building communities, such as fountains and swimming pools, are designed comprehensively through certain filtering measures and used as fire water in case of fire.

2, the general layout should be reasonable.

Modern architecture attaches great importance to the environmental design of streets or communities, and garden designs such as small bridges, flowing water, rockeries and greening are widely used. However, if some landscape designs are not handled properly, it will have a negative impact on the fire lanes and ladder trucks of high-rise buildings. We think that when planning the general layout of a street or residential area, the long side of a high-rise building should be arranged along the edge of the street or residential area as far as possible, and the adjacent municipal roads should be fully used to prevent fire engines from entering the residential area sometimes, so as to facilitate fire fighting and personnel rescue, and at least one fire lane can be designed in the residential area (this fire lane should be able to withstand the pressure of fire engines), which greatly saves the civil engineering cost and can kill two birds with one stone. In terms of building spacing, priority should be given to meeting the fire spacing. When there are difficulties, the adjacent walls should also be designed as firewalls without windows and balconies.

3, the basement drainage

Fire pump room, substation and diesel generator room are often located in the basement of high-rise buildings. If the basement is flooded, where to put out the fire? Therefore, the drainage in the basement is as important as the drainage at the bottom of the fire elevator in a sense. In fact, how to discharge the water that caused the basement flooding in time is often ignored by designers. There are still many problems in the design of drainage facilities at the bottom of fire elevator: (1) The elevator goes down to the basement, and a sump is set under the elevator foundation pit (common in preliminary design). This is not feasible, and the structure is not easy to handle, and the construction is also difficult. More importantly, where do submersible pumps and pressure drains enter the sump? Unless the sump area is increased to be larger than the elevator shaft, it will bring unnecessary structural difficulties, construction difficulties and large investment. Don't go down to the lowest floor, up to half a floor. (2) The sump volume is not enough, and the displacement does not meet the specification requirements. (3) The spare pump is not considered in most designs, and the spare pump is considered in some designs. But the power supply of the drainage pump is ordinary power supply. In case of fire, the ordinary power supply will be cut off. Whether there is a spare pump or not, drainage will become an empty talk. Pay attention to this article.

4. Fire alarm signal system

At present, most of the first-class high-rise buildings are equipped with automatic fire alarm systems, mainly for the control of fire elevators and smoke control systems. Most detectors are smoke-sensitive, which are distributed in public places such as elevator halls, walkways and stairs, but the actual effect is not ideal. Because it takes a long time for smoke to reach the detector from indoor through the well-sealed household door, it can't play the role of early fire detection. We think that conditional high-rise buildings can consider setting smoke detectors in kitchen, living room and other building parts that are easy to find fires early, and the effect will be very good. Therefore, the fire alarm system design of high-rise buildings should find the fire at an early stage and configure it reasonably. Fire alarm system can also be combined with the overall consideration of intelligent design of buildings, and fire detectors, manual alarm buttons and other sensing devices can be brought into the intelligent system, which can be set up and managed in a unified way.

We think that at least one drainage sump and water pump at the bottom of the fire elevator and other parts of the basement should meet the requirements of GB50045-95, 6.3.3. 1 1. In addition, the equipment must use pumps, one for use and one for standby, which should be automatically switched, and the high and low water levels of the sump should be automatically controlled to open and close the pumps. It must be the fire power supply. It is recommended to use QW non-blocking submersible sewage pump, and the pressure drainage pipe should be two independent drainage pipes, one for use and one for standby.

3 abstract

Problems and solutions of high-rise building fire protection design system often encountered in work. The fire storage in the high-level water tank, the setting and volume of the fire storage box, the adoption of double-valve and double-outlet fire hydrants, and the distance between the fire hydrant and the basement drainage need to be further discussed.

I believe that after the above introduction, everyone has a certain understanding of the technical analysis of building fire protection design. Welcome to Zhong Da for more information.

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