Tent construction facilities are mainly temporary or semi-permanent projects composed of alloy-type materials or steel structure frames and new materials such as tarpaulins and membrane structures. For a focused and targeted analysis, tents are now divided into two categories: (1) Ordinary tents. This type of tent has three characteristics at the same time, namely, temporary, small in scale, and few people at the same time; (2) Tent. Such tents generally have two common and typical characteristics at the same time, that is, they are large in scale and have a large number of users at the same time. In addition, such tents are either temporary or permanent.
Because of the relationship between the size of the tent and the number of users, if certain fire prevention measures are not taken, the tent type facilities are bound to have a higher fire risk. This article mainly analyzes and discusses tent facilities.
1 Tent buildings and their fire hazards
Tent buildings and facilities are different from ordinary construction projects, so they are generally not within the scope of my country's construction engineering fire protection design, fire protection design review, and fire protection completion acceptance. However, due to its flexibility and convenience in performance, it is increasingly being widely used in various social life places. When the number of people working in the tent is large, such as temporary tents used for large-scale events, auto shows, weddings, etc., if certain fire safety design is not considered when used, if there are safety exits or insufficient width, there is no fire inside. Facilities, high-temperature lighting fixtures are too close to the tent, and wires are randomly pulled and connected, which can easily cause fires, causing huge casualties and property losses. In addition to such temporary tents, there are also some tent construction facilities, which have a longer use time, and are basically no different from permanent construction facilities. This type of tent is the most used in large amusement parks, and its corresponding fire The risk is even greater, and users should increase their fire-fighting awareness, pay attention to the fire-fighting safety of the tent facilities, and must not build and use it at will.
2 Application status and characteristics of tents
2.1 Application status of tents
The tent originated in Europe and was introduced to China in 1995. With the booming development of my country's economy, it has also been widely used in exhibitions, auto shows, fashion shows, Oktoberfests, promotional celebrations, outdoor weddings, temporary exhibition halls or exhibition halls in resorts, etc. At present, many large-scale events, competitions and exhibitions are widely used in temporary tent facilities, such as the simple exhibition hall of the Shanghai International Expo Center, the Circus City of Cirque du Soleil, the Shanghai ATP1000 Masters, the London Championship Memorial and theater, and the UEFA Champions League Madrid Museum , Xlaisi new car exhibition, Beijing Olympics, Harvard University Sports Stadium, Shanghai World Expo, Shanghai Disney and so on.
2.2 The characteristics of the tent
(1) Flexible span design. Tent facilities generally can achieve different spans of 3.0~60.0 m, and the specific span can be increased or reduced according to actual needs.
(2) Simple, beautiful and easy to decorate. The tent can be matched with different colors or decorated inside and outside according to the characteristics of the environment and the scene, so that the entire tent can complement the surrounding environment or internal activities.
(3) Safe, stable and reliable. The tent structure generally adopts aluminum alloy frame, steel parts are connected, and the base is fixed, which has super mechanical properties. The tent is a flexible building (also called a flexible building). Because of its light weight, the structure design highlights the form of flexible restraint, abandoning the traditional fixed column foot, and adopts the hinged connection method to resist wind. In terms of load, the rotation of the hinge at the bottom of the column achieves the effect of consuming wind energy, so that the overall structure will not be damaged, and the wind resistance can reach 6-12 levels.
(4) Strong site adaptability. Because the self-weight of the tent is generally light, and the bearing capacity of the structural members is not high, it does not have special requirements for the site and foundation like general buildings. General sites such as sand, grass, cement and tiled floors can be adapted. , There is no need for special treatment of the venue.
(5) The requirements for supporting facilities are relatively low. Compared with general construction projects, tents have very low requirements for water supply and drainage, electromechanical, HVAC and other supporting facilities. Most tents only need to meet the basic electricity load requirements during use. There are basically no requirements.
(6) Simple structure, easy to install and disassemble. The tent structure is generally light-weight prefabricated fittings, and most tents can be assembled and disassembled directly on site, and there is no need for a long work cycle.
3 Fire hazard analysis of tents and burning characteristics of tarpaulin materials
3.1 Fire hazard analysis
For tent facilities of different sizes, the fire hazard is also significantly different. Based on the comprehensive analysis of the function or nature of the tent, interior requirements, and fire cases, the fire hazards of the tent facilities are summarized as follows:
(1) There are a large number of users and it is difficult to evacuate. Since there is no fire protection design code for tent-type facilities in China, in many engineering applications, the design basically does not consider the related issues of evacuation, such as evacuation distance, evacuation width, number of safe exits, etc., resulting in many densely populated tents. There are big problems in the evacuation design. Some tents that can accommodate more than a hundred people have only one safety exit or evacuation exit. In the event of a fire, the internal personnel often have only one evacuation exit for evacuation, which is very easy to cause a "bottleneck effect", leading to unfavorable evacuation, which in turn leads to a stampede accident and even more unfavorable evacuation factors.
(2) There are many electrical equipment, and the phenomenon of disorderly connection and wiring is common. Basically all types of tent facilities have this problem, and most users have little or no knowledge of fires caused by electricity. Even if they understand that careless use of electricity can cause fires, some people will take a fluke and ignore the safety of electricity. Whether the quality of the wire meets the requirements, whether there is aging, whether the device contact is good and reliable, whether the wiring meets the fire protection requirements, whether the circuit design and installation construction are completed by professional electricians, these factors are all potential hazards that cause electricity to catch fire. If you don't strengthen your understanding, any error in any factor may cause a fire.
(3) There are many combustibles inside, which can easily cause and expand the fire. Not all tents have this problem. The internal layout or display facilities of tent facilities with different functions and properties will be different, and the corresponding fire load density or combustible properties will also be different. For example, wedding tents are very random in setting up this type of tent, coupled with the user's low awareness of fire prevention, the various wedding decorations (such as ribbons, balloons), dining tables, dining chairs, table cloths, carpets, etc., are basically arranged inside. It is combustible (no flame retardant treatment requirements). Once a fire occurs in the tent, so many combustibles are bound to contribute to the fire and expand fire damage and losses.
(4) The internal fire-fighting facilities are not perfect, or there is basically no fire-fighting facilities. For general construction projects, professional fire protection facilities or systems can be designed according to specifications, but for tent-type facilities, because there are no regulatory constraints, it is often difficult for users to consider professional fire protection systems or facilities responsibly. Go in. Once a fire occurs in the tent, it is difficult for personnel to intervene or restrict the initial fire at the first time, which will cause a small fire to cause a large fire and cause greater personnel and property losses.
(5) The structure has poor fire resistance, and the tarpaulin material has poor flame resistance. This problem involves two aspects. (1) There is no professional technical standard as a guide for the design and construction of the tent. The structural system generally does not consider fire protection at all, so the fire resistance limit of the entire structural system is very low, and it is easy to collapse in the event of a fire; ( 2) Since there are no strict specifications, the tarpaulin materials used in many tents may not necessarily consider flame-retardant treatment, and some tarpaulins may also produce melt drips or drips when they burn. In the event of a fire, the tarpaulin material can easily cause the fire to spread and affect the safety of the structure.
(6) Insufficient external fire fighting infrastructure and rescue conditions. As mentioned earlier, the tent facilities do not have high requirements for the site. This flexibility makes the location of the tent construction likely to be far away from the fire water source, municipal or outdoor fire hydrants and fire drive lanes. Once a fire occurs in the tent, fire protection It is difficult for vehicles to get close to the tent, and the lack of external fire-fighting water sources will greatly affect the fire fighting of the tent.
3.2 Burning characteristics of tarpaulin materials
In order to analyze the burning characteristics of tarpaulin materials in a more scientific and detailed manner, the author conducted related experiments with a laboratory for tarpaulin materials provided by a professional tent manufacturer. The experimental contents and conclusions are shown in Table 1.
Table 1 Experimental summary of burning characteristics of tarpaulin materials
4 Principles of fire protection design for tents
In view of the current situation where there are no relevant fire protection design requirements in China, the author suggests that the following fire safety design principles should be fully considered on the basis of meeting actual use requirements for tent-type building facilities.
(1) Professional construction, suitable material selection. The construction of tent facilities must be carried out by a professional company. The company should learn from the technical level of the same industry to establish and improve its own design and construction standards to ensure the stability and safety of the tent building structure; the tarpaulin materials used in the construction of the tent should be given priority Choose materials with better flame retardant properties. It is recommended to entrust a laboratory to determine the combustion performance. It is recommended to use materials with a combustion performance not lower than B1.
(2) Control the scale of the tent and optimize the layout of the tent. Under the condition that it can basically meet the requirements of use, the overall scale and area of ??the tent should be controlled as much as possible. It is recommended to control in accordance with the requirements of the fire protection zone area of ??600 m 2 for civil buildings with the fourth-class fire resistance level in the GB 50016-2014 "Code for Fire Protection Design of Buildings". . A certain fire separation distance should be considered between multiple tents. The fire separation distance can be calculated and determined according to the actual situation (including tent materials, construction height, dominant wind direction, maximum wind speed, etc.). According to related experimental studies, when the wind speed does not exceed 2.2 m/s, and the distance between adjacent tents is not less than 2.644 m, the maximum heat radiation intensity is not easy to ignite the adjacent tents. In addition, when selecting the construction site for the tent, it should be finally arranged near the road where firefighting vehicles can reach smoothly, and it should be ensured that there is a certain water source near the tent (including water sources such as pools, swimming pools, and municipal or outdoor fire hydrants, etc.).
(3) Pay attention to safe evacuation design and strengthen safe evacuation exits. (1) When building the tent, it is necessary to reasonably set up sufficient safety exits for evacuation according to the specific shape and internal space layout. It is recommended to design according to the principle that the evacuation time of all the people in the tent to the outdoors does not exceed 1.5 min; (2) ) The number of safety exits should be at least two; (3) The distance from any point in the room to the nearest safety exit should not exceed 30 m; at the same time, it is recommended that the safety exit of the tent should be structurally disconnected from the main structure of the tent. Ensure that the safety of the safety exit will not be affected when the tent collapses.
(4) Electrical fire protection and wiring laying. The electrical equipment in the tent (including switches, sockets, lighting fixtures, heating equipment, etc.) should not be installed directly adjacent to or arranged on combustible materials or tarpaulin materials. When installed or arranged next to each other, fire and heat insulation protection measures should be taken. When using high-power heating equipment and spotlights in the tent, no combustibles should be placed in the 200% of the projection range of the equipment, and attention should be paid to control the distance between the high-temperature part and the combustibles. For the electrical wiring and laying of electrical equipment in the tent, it is recommended to use low-smoke, halogen-free flame-retardant wires, cables or mineral insulated cables. If other ordinary wires and cables are used, metal pipes or metal trunking should be used for protection , The end of the metal pipe or wire groove is sealed.
(5) Emergency lighting and evacuation instructions. For tents that have been used for a long time or have no natural lighting environment, it is recommended to install a certain number of self-powered rechargeable emergency lamps in the tent to ensure that a temporary lighting evacuation environment can be provided for evacuation in the event of a fire and power failure. . For tents with relatively complicated internal evacuation routes, it is also recommended to set up light-storing evacuation indication signs at high or low positions in combination with evacuation routes to provide evacuation guidance for evacuation.
(6) Fire fighting facilities and equipment. Under normal circumstances, tent construction facilities will not be equipped with automatic fire alarm systems, automatic fire extinguishing systems, and smoke prevention and exhaust systems. Therefore, considering the actual use of the tent, I suggest that at least a certain number of portable fire extinguishers should be installed in the tent, so as to ensure that in the early stage of a fire, internal personnel can use the fire extinguisher to intervene and control the fire at the first time.
5 concluding remarks
Based on the author's many years of experience in fire protection supervision and management, combined with the problems and potential safety hazards in the actual use of tent facilities, as well as experimental phenomena and data, this article has carried out some preliminary discussions on the fire safety design of tent construction facilities, and aims to induce use through this article The author attaches great importance to the fire safety of tent facilities, and at the same time, I would like to use this article to call on relevant departments to formulate some relevant standards for the fire protection design of tent facilities.