In the “Fire Engineering” published in April 2006, we discussed the issues that should be considered when a fire occurs in a one-story commercial building. Here, we will review some of the main construction components that may affect your fire protection strategy.
Below, we take a steel structure multi-storey building as an example to illustrate how it affects the stability of each building at various stages of the building (photos 1, 2).
Column structural member with compression effect. They transmit the weight of the roof and transfer it to the ground. The failure of the column may cause the sudden collapse of part or all of the building. In this example, the studs are fixed to the concrete pad at the floor level and bolted to the I-beam near the roof level. In the event of a fire, steel beams at the ceiling or roof height will heat up and begin to expand and twist. The expanded steel can pull the column away from its vertical plane. Among all building components, the failure of the column is the greatest danger. If you see a column that appears to be slanted or not completely vertical, please notify the Incident Commander (IC) immediately. The building must be evacuated immediately and a roll call must be made (photo 3).
Steel beam-a horizontal beam that supports other beams. The girders are designed to carry heavy objects, and they rest on the uprights. As fire and heat begin to erode the girders, the steel begins to absorb heat. At about 1,100°F, the steel will begin to fail. At this temperature, the steel begins to expand and twist. A 100-foot-long steel beam may expand by about 10 inches. Once the steel starts to expand and twist, the columns supporting the steel beams also start to move. The expansion of the steel may cause the walls at both ends of the girder to push out (if the steel crashes into a brick wall), which may cause the wall to bend or crack (photo 4).
Light steel truss beam joists-a parallel array of light steel beams, used to support floors or low slope roofs. The front, middle and rear steel beams of the building support lightweight trusses. The joist is welded to the steel beam. In the event of a fire, the lightweight truss will quickly absorb heat and may fail within five to ten minutes. If the roof is equipped with air conditioning and other equipment, the collapse may happen more quickly. Do not try to cut the reinforced joist roof. Doing so may cut off the upper chord of the truss, the main load-bearing member, and may cause the entire truss structure and roof to collapse.
The spacing of the joists can be about four to eight feet apart. Such a wide spacing is one of the reasons why you don’t want to cut a roof with light steel joists and a Q-shaped roof surface. The Deputy Commissioner of the New York Fire Department (retired) Vincent Dunn (Vincent Dunn) pointed out in “The Collapse of Fire Fighting Buildings: A Guide to Fire Safety” (Fire Engineering Books and Videos, 1988): “The difference between wooden joists and steel Important design differences The top support system of joists is the spacing of the joists. The spacing between the open steel mesh joists is up to 8 feet, depending on the size of the steel bars and the roof load. The wide space between the joists even when there is no steel joists In the case of the danger of collapse, there are also several dangers for firefighters to cut the opening on the roof deck. First, when the contour of the cut is nearly complete, and if the roof is not directly above one of the wide-spacing steel joists , The cut top plate may suddenly bend or hinged downward in the fire. If one foot of the firefighter is in the roof cut, he may lose his balance and fall into the fire below with a chainsaw (photo 5) .(138)
Steel doors-horizontal steel supports redistribute the weight of the bricks over the window openings and doorways. These steel sheets are usually used in “L” shapes for smaller openings, while I-beams are used for larger openings. The door tel is tied in the masonry wall on either side of the opening. Just like other steel, once the door lin gets hot, it starts to expand and twist. The failure of the steel lintel may cause the upper wall to collapse (photos 6 and 7).
Facade-the outer surface of the building. Light steel components form the frame of the facade. Waterproof plaster material is used to close the attic. Lightweight steel will quickly lose structural strength and rigidity in a fire. Ventilation of the attic can be achieved by breaking through the gypsum sheath instead of placing firefighters on the roof. The strength of this external plaster is similar to the plasterboard used in most interior walls of houses. After the gypsum sheath is installed in place, the constructor applies Styrofoam® on the plaster and then coats the plaster (photos 8, 9).
Roof surface. The material used to construct the roof surface of the building is easy to construct. First, the Q-shaped decorative steel nails are welded to the reinforced joists. Then, place the foam insulation material on the Q-shaped decorative board and fix it to the deck with screws. After the insulation material is installed in place, glue the rubber film to the foam insulation material to complete the surface of the roof.
For low slope roofs, another roof surface you may encounter is polystyrene foam insulation, covered with 3/8 inch latex modified concrete.
The third type of roof surface consists of a layer of rigid insulation material fixed to the roof deck. Then the asphalt felt paper is glued to the insulation layer with hot asphalt. The stone is then laid on the roof surface to fix it in place and protect the felt membrane.
For this type of structure, do not consider cutting the roof. The probability of collapse is 5 to 10 minutes, so there is not enough time to ventilate the roof safely. It is desirable to ventilate the attic through horizontal ventilation (breaking through the facade of the building) instead of placing the components on the roof. Cutting any part of the truss may cause the entire roof surface to collapse. As described above, the roof panels can be hinged downward under the weight of the members that cut the roof, thereby sending people into the fire building. The industry has enough experience in light trusses and it is strongly recommended that you remove them from the roof when members appear (photo 10).
Suspended ceiling aluminum or steel grid system, with steel wire suspended on the roof support. The grid system will accommodate all ceiling tiles to form the finished ceiling. The space above the suspended ceiling poses a great danger to firefighters. Most commonly called “attic” or “truss void”, it can hide fire and flames. Once this space is penetrated, explosive carbon monoxide may be ignited, causing the entire grid system to collapse. You must check the cockpit early in the event of a fire, and if the fire suddenly explodes from the ceiling, all firefighters should be allowed to escape the building. Rechargeable mobile phones were installed near the door, and all firefighters were wearing full turnout equipment. Electrical wiring, HVAC system components and gas lines are just some of the building services that may be hidden in the voids of the trusses. Many natural gas pipelines can penetrate the roof and are used for heaters on top of buildings (photos 11 and 12).
Nowadays, steel and wood trusses are installed in all types of buildings, from private residences to high-rise office buildings, and the decision to evacuate firefighters may appear earlier in the evolution of the fire scene. The construction time of the truss structure has been long enough so that all fire commanders should know how the buildings in it react in the event of a fire and take corresponding actions.
In order to properly prepare integrated circuits, he must start with the general idea of building construction. Francis L. Brannigan’s “Fire Building Structure”, the third edition (National Fire Protection Association, 1992) and Dunn’s book have been published for some time, and it is a must-read for all members of the fire department book.
Since we usually don’t have time to consult construction engineers at the fire scene, the responsibility of IC is to predict the changes that will occur when the building is burning. If you are an officer or aspire to be an officer, you need to be educated in architecture.
JOHN MILES is the captain of the New York Fire Department, assigned to the 35th ladder. Previously, he served as a lieutenant for the 35th ladder and as a firefighter for the 34th ladder and the 82nd engine. (NJ) Fire Department and Spring Valley (NY) Fire Department, and is an instructor at the Rockland County Fire Training Center in Pomona, New York.
John Tobin (JOHN TOBIN) is a veteran with 33 years of fire service experience, and he was the chief of the Vail River (NJ) Fire Department. He has a master’s degree in public administration and is a member of the advisory board of the Bergen County (NJ) School of Law and Public Safety.
In the “Fire Engineering” published in April 2006, we discussed the issues that should be considered when a fire occurs in a one-story commercial building. Here, we will review some of the main construction components that may affect your fire protection strategy.
Below, we take a steel structure multi-storey building as an example to illustrate how it affects the stability of each building at various stages of the building (photos 1, 2).
Column structural member with compression effect. They transmit the weight of the roof and transfer it to the ground. The failure of the column may cause the sudden collapse of part or all of the building. In this example, the studs are fixed to the concrete pad at the floor level and bolted to the I-beam near the roof level. In the event of a fire, steel beams at the ceiling or roof height will heat up and begin to expand and twist. The expanded steel can pull the column away from its vertical plane. Among all building components, the failure of the column is the greatest danger. If you see a column that appears to be slanted or not completely vertical, please notify the Incident Commander (IC) immediately. The building must be evacuated immediately and a roll call must be made (photo 3).
Steel beam-a horizontal beam that supports other beams. The girders are designed to carry heavy objects, and they rest on the uprights. As fire and heat begin to erode the girders, the steel begins to absorb heat. At about 1,100°F, the steel will begin to fail. At this temperature, the steel begins to expand and twist. A 100-foot-long steel beam may expand by about 10 inches. Once the steel starts to expand and twist, the columns supporting the steel beams also start to move. The expansion of the steel may cause the walls at both ends of the girder to push out (if the steel crashes into a brick wall), which may cause the wall to bend or crack (photo 4).
Light steel truss beam joists-a parallel array of light steel beams, used to support floors or low slope roofs. The front, middle and rear steel beams of the building support lightweight trusses. The joist is welded to the steel beam. In the event of a fire, the lightweight truss will quickly absorb heat and may fail within five to ten minutes. If the roof is equipped with air conditioning and other equipment, the collapse may happen more quickly. Do not try to cut the reinforced joist roof. Doing so may cut off the upper chord of the truss, the main load-bearing member, and may cause the entire truss structure and roof to collapse.
The spacing of the joists can be about four to eight feet apart. Such a wide spacing is one of the reasons why you don’t want to cut a roof with light steel joists and a Q-shaped roof surface. The Deputy Commissioner of the New York Fire Department (retired) Vincent Dunn (Vincent Dunn) pointed out in “The Collapse of Fire Fighting Buildings: A Guide to Fire Safety” (Fire Engineering Books and Videos, 1988): “The difference between wooden joists and steel Important design differences The top support system of joists is the spacing of the joists. The spacing between the open steel mesh joists is up to 8 feet, depending on the size of the steel bars and the roof load. The wide space between the joists even when there is no steel joists In the case of the danger of collapse, there are also several dangers for firefighters to cut the opening on the roof deck. First, when the contour of the cut is nearly complete, and if the roof is not directly above one of the wide-spacing steel joists , The cut top plate may suddenly bend or hinged downward in the fire. If one foot of the firefighter is in the roof cut, he may lose his balance and fall into the fire below with a chainsaw (photo 5) .(138)
Steel doors-horizontal steel supports redistribute the weight of the bricks over the window openings and doorways. These steel sheets are usually used in “L” shapes for smaller openings, while I-beams are used for larger openings. The door tel is tied in the masonry wall on either side of the opening. Just like other steel, once the door lin gets hot, it starts to expand and twist. The failure of the steel lintel may cause the upper wall to collapse (photos 6 and 7).
Facade-the outer surface of the building. Light steel components form the frame of the facade. Waterproof plaster material is used to close the attic. Lightweight steel will quickly lose structural strength and rigidity in a fire. Ventilation of the attic can be achieved by breaking through the gypsum sheath instead of placing firefighters on the roof. The strength of this external plaster is similar to the plasterboard used in most interior walls of houses. After the gypsum sheath is installed in place, the constructor applies Styrofoam® on the plaster and then coats the plaster (photos 8, 9).
Roof surface. The material used to construct the roof surface of the building is easy to construct. First, the Q-shaped decorative steel nails are welded to the reinforced joists. Then, place the foam insulation material on the Q-shaped decorative board and fix it to the deck with screws. After the insulation material is installed in place, glue the rubber film to the foam insulation material to complete the surface of the roof.
For low slope roofs, another roof surface you may encounter is polystyrene foam insulation, covered with 3/8 inch latex modified concrete.
The third type of roof surface consists of a layer of rigid insulation material fixed to the roof deck. Then the asphalt felt paper is glued to the insulation layer with hot asphalt. The stone is then laid on the roof surface to fix it in place and protect the felt membrane.
For this type of structure, do not consider cutting the roof. The probability of collapse is 5 to 10 minutes, so there is not enough time to ventilate the roof safely. It is desirable to ventilate the attic through horizontal ventilation (breaking through the facade of the building) instead of placing the components on the roof. Cutting any part of the truss may cause the entire roof surface to collapse. As described above, the roof panels can be hinged downward under the weight of the members that cut the roof, thereby sending people into the fire building. The industry has enough experience in light trusses and it is strongly recommended that you remove them from the roof when members appear (photo 10).
Suspended ceiling aluminum or steel grid system, with steel wire suspended on the roof support. The grid system will accommodate all ceiling tiles to form the finished ceiling. The space above the suspended ceiling poses a great danger to firefighters. Most commonly called “attic” or “truss void”, it can hide fire and flames. Once this space is penetrated, explosive carbon monoxide may be ignited, causing the entire grid system to collapse. You must check the cockpit early in the event of a fire, and if the fire suddenly explodes from the ceiling, all firefighters should be allowed to escape the building. Rechargeable mobile phones were installed near the door, and all firefighters were wearing full turnout equipment. Electrical wiring, HVAC system components and gas lines are just some of the building services that may be hidden in the voids of the trusses. Many natural gas pipelines can penetrate the roof and are used for heaters on top of buildings (photos 11 and 12).
Nowadays, steel and wood trusses are installed in all types of buildings, from private residences to high-rise office buildings, and the decision to evacuate firefighters may appear earlier in the evolution of the fire scene. The construction time of the truss structure has been long enough so that all fire commanders should know how the buildings in it react in the event of a fire and take corresponding actions.
In order to properly prepare integrated circuits, he must start with the general idea of building construction. Francis L. Brannigan’s “Fire Building Structure”, the third edition (National Fire Protection Association, 1992) and Dunn’s book have been published for some time, and it is a must-read for all members of the fire department book.
Since we usually don’t have time to consult construction engineers at the fire scene, the responsibility of IC is to predict the changes that will occur when the building is burning. If you are an officer or aspire to be an officer, you need to be educated in architecture.
JOHN MILES is the captain of the New York Fire Department, assigned to the 35th ladder. Previously, he served as a lieutenant for the 35th ladder and as a firefighter for the 34th ladder and the 82nd engine. (NJ) Fire Department and Spring Valley (NY) Fire Department, and is an instructor at the Rockland County Fire Training Center in Pomona, New York.
John Tobin (JOHN TOBIN) is a veteran with 33 years of fire service experience, and he was the chief of the Vail River (NJ) Fire Department. He has a master’s degree in public administration and is a member of the advisory board of the Bergen County (NJ) School of Law and Public Safety.
Post time: Mar-26-2021