New technology for safe evacuation and escape of high-rise buildings

Modern high-rise buildings are like a small city arranged vertically, with a high concentration of people and complex and diverse functions. There are many combustible materials in the interior decoration and exterior wall insulation, and there are dense vertical pipe wells such as cable wells, ventilation ducts, and pipe wells, as well as gaps in the curtain walls. Air conditioning, lighting, and catering use a lot of electricity and gas. Once a fire occurs, under the influence of the "chimney effect", the smoke and fire spread quickly, the fire burns violently, and it is very difficult to extinguish, which can easily cause mass casualties.

Modern high-rise buildings have complex functions. Some are office buildings, some are residential apartment buildings, some are commercial complexes, some are hotels and restaurants, and some are outpatient ward buildings. There is a high concentration of people in the building. Some are relatively familiar with the building conditions, some are highly mobile and unfamiliar with the conditions inside the building, and some are vulnerable people such as the elderly, children, the sick, the disabled, and pregnant women. The situations vary greatly. Once a fire occurs, it is necessary to make full use of various fire-fighting facilities inside the building and actively carry out self-rescue and mutual rescue.

1. Safe evacuation of high-rise buildings

The characteristics of high-rise buildings determine that the basic concept of their fire safety design is "self-rescue first", that is, to make full use of the fire automatic alarm, automatic fire extinguishing, smoke exhaust, fire partition and other facilities inside the building to achieve the purpose of early alarm, rapid extinguishing and saving lives. In terms of safe evacuation, the maximum climbing height of the fire ladder truck is only about 100 meters, and it is almost impossible to evacuate people at such a height. Therefore, the internal evacuation facilities must be fully utilized. Fire cases show that only by mastering the necessary evacuation knowledge and safety self-rescue skills, and understanding the functions and use of high-rise building safety evacuation facilities, can we evacuate safely when a fire occurs.

1. Call the police promptly

After discovering a fire, you should immediately call 119 to report the fire, and briefly explain the location of the building on fire, the floor on which the fire broke out, the location of the fire and the burning materials, as well as whether the fire is fierce, your location, etc. Do not panic, or be too busy putting out the fire yourself and not report the fire, or report it late. Many serious fires have caused serious casualties because the parties involved did not report the fire in time after discovering the fire, delaying the best time to put out the fire.

Reporting fire in time is not only a basic obligation that citizens should fulfill in accordance with the Fire Protection Law, but also the most effective way to protect themselves and others when a fire occurs. From the law of building fires, it can be divided into five stages: initial, development, spread, fierce, decline and extinguishment. Generally, within 15 minutes, it is still in the initial stage. The burning area is not large, the flame is not high, the radiant heat is not strong, and the burning speed is not fast. If the fire brigade can carry out fire fighting in the initial stage, it will be helpful to control and extinguish the fire. On January 2, 2008, a fire broke out in the Dehui Plaza Wholesale Market in Urumqi, Xinjiang. The security guard of the unit was busy with fire fighting and did not call the police in time. After using a fire extinguisher to put out the fire himself, he used the indoor wall fire hydrant to put out the fire. Because there was no water in the fire hydrant, the fire spread rapidly. Several security guards at the scene felt that the fire was out of control and fled the scene. Later, a truck driver discovered the fire in front of the gate and called the police on his mobile phone. By the time the local fire brigade arrived at the scene after receiving the alarm, the fire was already burning fiercely and spreading rapidly, burning down more than 70,000 square meters of buildings. Two employees in the building died, and three firefighters died heroically while putting out the fire and saving lives.

Calling the police is the fastest and most convenient way. At the same time, we should also make full use of the manual fire alarm buttons in high-rise buildings. Modern high-rise buildings have manual fire alarm buttons in each fire compartment, which are usually located in obvious and easy-to-operate locations on the corridor walls. When using them, just break the glass and press the button, and the fire control room in the high-rise building will receive the alarm signal. After confirming the fire, you can also quickly report the fire.

2. Stay calm and act rationally

After discovering a fire or hearing a fire alarm, especially when thick smoke blocks your view, visibility is significantly reduced, you feel high temperatures or even see flames directly, you must overcome your fear, do not panic, and do not blindly take irrational actions such as jumping off a building. You must try to stay calm, make quick rational judgments about your environment, and use all conditions to choose the correct evacuation method.

[page]

According to my country's fire protection technical standards and specifications, high-rise buildings with fire alarm systems are generally equipped with fire emergency broadcasts. When a fire occurs, the public broadcast loudspeaker will be forced to switch to the fire emergency broadcast state, and the audio broadcast system of the bedside control cabinet in the guest room of a high-rise hotel can also be forced to switch to the fire emergency broadcast state to promptly inform the people in the building of the fire situation. People in the building must pay attention to the broadcast notification, accurately understand the situation in the building, and take corresponding actions according to different situations.

Situation 1: When a fire occurs in the room or hall you are in, if it is difficult to extinguish the initial fire after calling the police, you must evacuate quickly. When evacuating, close the door and call loudly for other people on the same floor to evacuate. In the 1985 Harbin Swan Hotel fire, American Andrick caused a fire by smoking in bed. He left the room after being awakened by the smoke, without closing the door or calling for help, and hurried downstairs. The flames in the guest room met the fresh air in the corridor, forming convection, and the fire quickly spread to the corridor. When the sleeping guests in other rooms discovered the fire, the fire had already blocked the door, resulting in heavy casualties.

Situation 2: When there is a fire in other parts of the same floor, you must not open the door at will. First, you should touch the door with your hand to test the temperature of the door. If the door is hot, you cannot open it, otherwise smoke and fire will rush into the room; if the door is not hot, it means that the fire is not big and you can open the door. If you can't see the open flame after opening the door, and the smoke is not thick, you should use the evacuation indicator signs installed on the wall to determine the evacuation direction, try to bend down, and escape to the corridor away from the direction of the smoke and fire. If conditions permit, it is best to wet your clothes first, or wrap your whole body with a wet blanket, and hold your head and other exposed parts with wet clothes. People in the hotel room should wear the spare smoke masks in the guest room. After leaving the room, be sure to close the door behind you to prevent the fire from spreading. If you encounter thick smoke, high temperature or even open flames, don't try to rush through the smoke and fire, but retreat quickly and find another escape route. Because once you inhale toxic and high-temperature smoke, it may cause respiratory burns or even poisoning and death in an instant.

The plane design of high-rise buildings follows the basic principle of "two-way evacuation", that is, any position can be evacuated in two different directions. A few buildings are limited by the plane layout and have "pocket corridors" that can only lead to one direction, which is commonly known as "dead ends", but the regulations strictly limit the length of "pocket corridors". If the trapped people happen to be in the range of the "pocket corridor" and the fire and smoke block this only corridor, they must retreat to the room and quickly close the door to ask for help.

Situation 3: When the fire is on other floors, you must also evacuate quickly, and you must not linger or be greedy for property. When leaving, you must close the door to limit the spread of the fire. It should be emphasized that some people believe that when a high-rise building is on fire, only the people who are directly threatened need to be evacuated immediately, and the corresponding safety evacuation concept is "partial evacuation, waiting for help on the spot", that is, when a fire occurs, only the people on the fire floor and the 1 to 2 floors above and below should be evacuated immediately. However, since fire itself is an accidental event full of uncertainty, the development of the fire is also difficult to estimate. If the evacuation opportunity at the beginning of the fire is missed, "waiting for help on the spot" may become "waiting to die"! The principle of "partial evacuation" is worth discussing. In fact, many high-rise building fires that have occurred internationally in recent years have taken a long time to urgently evacuate and evacuate all the people in the building. Therefore, after a fire occurs in a high-rise building, all personnel should be organized to evacuate in an orderly manner immediately to ensure safety.

[page]

Situation 4: If you are trapped in the room where the fire started, first of all, you should try to find other escape routes, such as whether you can move to the adjacent room through the corridor or balcony, and then use the door of the adjacent room to evacuate. Secondly, you should close the door and pour water to cool down. At the same time, try to get close to the street window, balcony and other places that are easy to be found, call 119, keep in touch with the operator, guide the rescuers to come to the rescue, and shout for help to the rescuers, throw sofa cushions, pillows, clothes and other soft objects downstairs, use a flashlight to shine down, and knock on metal utensils to make noises so that the rescuers can find you in time. While waiting for rescue, you can retreat to a relatively safe bathroom for a short period of refuge. After entering the bathroom, close the doors and windows tightly, block the gaps, turn on all the faucets to drain water, especially the bathtub, where water should be continuously drained to maintain a high water level. On the one hand, it is convenient to take water to pour on the doors and windows to cool down. On the other hand, when the fire spreads to the bathroom, people can lie in the bathtub to temporarily hide. Do not hide in closed locations such as under the bed, closet, and attic, as this may cause damage to the body due to flames or smoke, and it will be difficult for firefighters to find you, which can easily result in the death of trapped people.

If you are directly threatened by fireworks, the fire is life-threatening and there is no other way to save yourself, you must take certain risks and take positive actions, and never sit and wait for death. For example, you can stand on the balcony outside the window or the outdoor unit of the air conditioner to call for help. In the fire at the Harbin Swan Hotel, guests in three rooms turned over and climbed out of the window, holding on to the window sill with their hands and stepping on the 10-centimeter-wide protrusion outside the wall, and persisted until they were successfully rescued by the fire brigade. If you are in a lower position below the third floor, you can tie sheets, curtains, clothes, etc. into a rope, tie it to a solid place indoors, and slide the rope to save yourself. If you can escape by going down to a certain floor below, it is not necessary to reach the ground, and you can kick the glass to enter.

Do not jump from a building unless you have no other choice. If you will die if you don't jump from a building, choose something elastic to throw down before jumping, such as a spring mattress, sofa quilt, etc. Hold the pillow with both hands, bend your knees and jump down. If there is a life-saving air cushion below, stretch your limbs, lie flat on your back, and jump down facing the mark on the cushion. However, the safe application height of the life-saving air cushion is also within 10 meters. Therefore, if people trapped on the third floor or above jump from the upper floor, even with a life-saving air cushion, the probability of survival is extremely small.

3. Make full use of facilities in the building for evacuation

First, stairs are the most important evacuation facilities. The most important evacuation facilities in modern high-rise buildings are stairs. The important feature of high-rise building stairs that is different from other buildings is that they are set up with "enclosed stairs" and "smoke-proof stairs" according to different heights and usage functions. As the name suggests, "enclosed stairs" are stairs that have fire doors set at the location where each staircase leads to the corridor, and the stairwell is closed to prevent smoke and hot air from entering. "Smoke-proof stairs" are stairs that have smoke-proof antechambers, balconies, recessed corridors, etc. at the entrance of the stairwell. The air blower that automatically starts in the event of a fire can continuously supply fresh air to the antechamber and stairwell to ensure that a certain positive pressure is formed in the antechamber and stairwell, thereby preventing smoke and fire from entering. The typical evacuation route is: horizontally enter the corridor through the doors of rooms and halls, then enter the stairwell through the antechamber, vertical evacuation is mainly based on stairs, and finally complete the evacuation process through the safe exit directly leading to the outdoors.

Only when people in high-rise buildings know the location of safe evacuation stairs in normal times can they effectively use the stairs to evacuate in case of fire. To achieve this, fire drills should be carried out regularly for high-rise buildings with relatively fixed personnel, such as office buildings, residential buildings, and apartments, especially on-site evacuation drills. For high-rise buildings with high personnel mobility, such as hotels, restaurants, and shopping malls, on the one hand, more obvious evacuation signs should be set up, and on the other hand, long-term and extensive fire protection publicity and education should be carried out to cultivate the public's good habit of checking the location of evacuation stairs before entering unfamiliar places.

When using stairs to evacuate in case of fire, you must maintain a fast speed and good order. Carry forward the spirit of mutual assistance, take care of the elderly, children, disabled people and other people with limited mobility, and avoid scrambling for the road, crowding and even stampede accidents. When encountering firefighters and other emergency rescue personnel going up, you must take the initiative to give up the stair steps on one side to prevent collisions and stagnation.

[page]

Second, flexibly determine the evacuation direction. If the trapped person is close to the ground and below the floor where the fire broke out, he or she must evacuate downwards in the stairs, but he or she must pay attention to the floor signs to prevent the person from mistakenly entering the basement. If the person is on a floor above the floor where the fire broke out and the smoke and fire spreading upwards make it impossible to evacuate to the ground, he or she cannot escape downwards by force, but can escape upwards through the stairs and reach the rooftop platform. Because according to my country's fire protection technical specifications, high-rise buildings generally have at least two stairs that lead directly to the rooftop platform. In this way, on the one hand, you can evacuate downwards from other adjacent stairwells that are not affected by the fire, which is particularly common in high-rise residential buildings with multiple units. On the other hand, if you cannot use other stairs to evacuate, you can also temporarily avoid the fire on the floor and wait for rescue by firefighters.

Some super high-rise buildings have special refuge floors every 15 floors or so, and the refuge floors are equipped with special smoke-proof facilities. The plane position of the evacuation stairs changes at the refuge floor to ensure that people can continue to evacuate after passing the refuge floor, thus providing a temporary refuge space for trapped people. In high-rise buildings with refuge floors, trapped people can also choose to go to the nearest refuge floor to wait for rescue.

Third, use the elevator carefully while ensuring safety. Many high-rise buildings are equipped with fire elevators, which are usually used as passenger elevators and freight elevators. They are powered by a dedicated fire power supply and distribution line, and adopt safety measures to prevent the intrusion of smoke, fire and fire-fighting water. In case of fire, they can be forced to land on the first floor. Fire elevators are mainly used by firefighters, who carry fire-fighting equipment to quickly approach the fire point to launch fire-fighting and rescue operations. At the same time, under the organization of high-rise building fire management personnel and on-site firefighters, fire elevators can also be used for safe evacuation, especially for evacuating people with limited mobility such as disabled people and patients in wheelchairs.

"Ordinary elevators cannot be used during fires" is a consensus of the fire protection community at home and abroad. The main purpose is to prevent the high-temperature smoke and fire-fighting water from spreading and flowing to the front room and elevator shaft during a fire, causing elevator failures and outages, trapping people, and then causing casualties due to smoke and fire threats. In fact, there have been many accidents at home and abroad where casualties were caused by blind use of elevators during fires. However, for high-rise buildings that accommodate tens of thousands of people at the same time, if only stairs are used for evacuation in an emergency, it will take several hours to evacuate all personnel. During this period, if the fire is out of control or the stairs are destroyed, serious casualties will inevitably occur. Therefore, there are also records of successful use of elevators for evacuation in many high-rise building fires, and sometimes elevators have played a key role. In the "9.11" incident, after Building 1 of the World Trade Center in New York was hit by a plane, about 3,000 people in Building 2 were successfully evacuated from floors above the 78th floor before the plane hit Building 2, and most of them were evacuated by elevator.

2. New technology for evacuation of high-rise buildings

It takes a long time to evacuate all personnel in a high-rise building in a fire. In particular, during the 9/11 incident, the trapped personnel in the twin towers of the World Trade Center jumped from more than 100 floors in despair. The tragic scene shocked people and also inspired countries around the world to attach great importance to auxiliary evacuation facilities for high-rise buildings. In recent years, various high-rise building evacuation and escape facilities have emerged to deal with non-traditional security threats such as fire, explosion, nuclear, biological and chemical terrorist attacks.

[page]

1. Safety elevator

As early as the early 1990s, elevator experts from the American Society of Mechanical Engineers pointed out that it is entirely possible to improve the design of elevator vestibules and elevator shafts, improve the reliability of control systems and electromechanical systems, and effectively prevent elevator vestibules and elevator shafts from being threatened by smoke, fire and water stains, and build "safe elevators" that can still be used during fires, thus breaking the restriction that "elevators cannot be used during fires." There are records of successful use of elevators for evacuation in many high-rise building fires, and sometimes elevators have played a key role. In the "9.11" incident, after Building 1 of the World Trade Center in New York was hit by a plane, about 3,000 people in Building 2 were evacuated from floors above the impact point before the plane hit Building 2, and most of them were evacuated by elevator.

Experts pointed out that elevators are the most important and only vertical transportation tool in high-rise buildings. Since they can transport people to a height of 400 to 500 meters in a few minutes or even shorter, they should also be able to transport people back to the ground safely and quickly in an emergency. This is in line with the characteristics of high-rise buildings and is technically feasible. At least in super high-rise buildings, hotels, hospitals and other high-rise buildings, elevators should be used to organize evacuations as soon as possible from the first moment, while ensuring safety.

The 2009 edition of the National Fire Protection Association standard NFPAl01 "Life Safety Code" added content on how to prevent smoke from entering the antechamber and prevent water from flowing into the elevator shaft in the appendix, and proposed that if smoke can be prevented from entering the antechamber and the emergency broadcast system can report the fire in real time, elevators can be used to organize evacuation of people in case of fire, and the elevator antechamber must lead directly to the safe evacuation stairwell.

In this way, once the elevator is forced to land by the fire department, people waiting to evacuate by elevator can use the stairs to evacuate. However, even if the elevator can be used for personnel evacuation, it cannot reduce the requirements for the number and evacuation capacity of safe evacuation stairs in high-rise buildings.

In March 2009, the project "Feasibility Study of Elevator Emergency Evacuation in High-Rise Hotel Fires" approved by Shanghai Science and Technology Commission and undertaken by Shanghai Fire Research Institute of the Ministry of Public Security passed the expert demonstration. During the research process, a staircase and elevator mixed evacuation experiment was conducted on September 28, 2007 at the 88-story Jinmao Building, verifying the necessity and feasibility of using elevators to organize evacuation in the early stage of a fire.

(II) Zoomable slide

The scalable slideway is made of wear-resistant and flame-retardant nylon material and high-strength metal ring frame. It can be folded and stored on the top floor or other floors of a high-rise building. In case of fire, it can be opened and released to the ground, and the end is fixed to a pre-determined anchor point on the ground. The trapped people enter in turn and slide down to the ground. In an emergency, a ladder truck can be used to deploy it at the window close to the trapped people in the high-rise building, or even a helicopter can be used to drop it onto the roof of the high-rise building, and the firefighters can deploy it to evacuate the trapped people on the roof.

The zoom slide has been recognized by Japan's fire protection regulations as a safe evacuation method. In the United States, it is only used as a backup evacuation facility for high-rise buildings such as airport control towers. The key indicators of this type of product are to reasonably set the sliding angle and effectively control the sliding speed through the friction between the slide material and the body of the messenger. With the application of high-friction coefficient materials, zoom slides that can be used in special building shafts have appeared in Europe. At present, companies in the United States, Israel and other countries have developed multiple series of such products. The AMEs series of products of an Israeli company can be deployed from the 11th floor within 90 seconds and evacuate people downward at a rate of 15 people per minute. It was named one of the top ten inventions of 2002 by Time magazine in the United States.

3. Descenders and parachutes

[page]

As a reciprocating refuge and self-rescue escape device, the descender is mainly composed of a rope and a safety belt or a protective sleeve. It does not require other power. The descending speed of the descending rope is controlled by a braking mechanism to ensure that the user always maintains a certain speed balance by relying on his own weight and descends safely to the ground. The descender is the most widely used auxiliary safety evacuation product on the market. In order to improve efficiency, some descenders are equipped with a set of safety belts at both ends of the descending rope. When one person reaches the ground, the safety belt at the other end of the rope rises to the initial position, thereby ensuring continuous use by the next person. Other descenders use flame-retardant bags instead of traditional safety belts. This flame-retardant bag can protect the whole body of the escapee, including the head, to block heat radiation and reduce the escapee's fear of heights when looking down at the ground.

At present, there are more than 100,000 sets of uL-certified descenders installed in various parts of Japan. Although the maximum design height of some products is hundreds of meters, considering the influence of wind force and psychological factors, they are generally only suitable for high-rise buildings of about 10 floors. During the demonstration, a two-person descender of an American company safely slid 30 people down from the 10th floor in 4 minutes and 15 seconds.

In recent years, some American companies have also designed parachutes for high-rise building escape. The principle is the same as that of ordinary parachutes, and no special training is required. When using it, wear the parachute bag, tie the parachute opening rope to a secure position indoors, and then jump from the roof or window. Since opening the parachute requires a process, it is only suitable for use on floors above 15 floors or above 40 meters. However, since it is easily affected by wind, especially the unstable airflow in the fire scene, and the user will have a huge fear, the role of parachutes in evacuation is still controversial.

(IV) Outdoor evacuation rescue cabin

It consists of one or more escape and rescue capsules that are folded and stored on the roof and a rack rail installed on the exterior wall. In case of fire, professionals use a winch installed on the roof to introduce the unfolded escape and rescue capsule into the slide rail installed on the exterior wall of the building. The escape and rescue capsule can dock with windows on multiple floors at the same time to send trapped people in high-rise buildings to the ground, and can also send firefighters and other emergency rescue personnel into the building while rising.

This type of facility is far more complex than a zoom slide and a descender, with a large one-time investment. It needs to be used and controlled by specially trained personnel, and needs regular maintenance, care and inspection. In addition, the roof winch that serves as its power must have reliable power guarantee. Its advantage is that it can evacuate multiple people in each reciprocating operation, and is especially suitable for evacuating disabled people in wheelchairs and other people with limited mobility. Moreover, after sending the trapped people to the ground when running downward, it can also transport rescuers to the upper part when running upward.

In July 2004, Israel installed this type of product with five escape and rescue cabins in a 21-story high-rise building for the first time, which can evacuate 150 people at a time. At present, this product has been certified by the Israeli Ministry of Labor and Social Welfare and the Israeli National Standards Committee, and was awarded the "Anti-Terrorism Technology Certification" by the US Department of Homeland Security in 2005. There are also manufacturers in China that have developed similar products. Rescue cabins that can run up and down in an alternating manner have been installed in the Xicheng District People's Government, Fuxing Hospital, Cancer Hospital, Anzhen Hospital and China Telecom Headquarters Building in Beijing.