The Model Incident Command System Series Firefighter Casualties (continued)

The Model Incident Command System Series Firefighter Casualties (continued)

FEATURES

STRATEGY AND TACTICS

In this seventh article on the model incident command system, the authors conclude their discussion of fire-related injuries by focusing on the indicators of collapse and the value of a safety officer—particularly on the fireground.

Structural collapse is the fourth leading cause of firefighter deaths, following stress, falls/ struck by objects, and exposure to fire products (see FIRE ENGINEERING, December 1984).

There are texts, such as BUILDING CONSTRUCTION FOR THE FIRE SERVICE by F. L. Brannigan, that offer in-depth studies of building construction. These should be studied by all fire officers and firefighters.

Many factors affect the fire resistance of buildings. No one can predict with total accuracy how an individual building will behave under fire conditions; however, the incident commander must possess a basic knowledge of the major problems associated with various types of buildings. He must be able to recognize the key faults and weaknesses of a particular building that can cause injury or death to his firefighters. The incident commander should be cognizant of what is occurring to the structural integrity of the fire building, and must know when to pull his companies out of a structure that is being weakened by the effects of a fire.

Many times, when reading case histories, we come across the statement, “The building collapsed without warning.” Is this really true, or were the signs of potential collapse ignored, not recognized, or not communicated to the incident commander by company officers or sector commanders?

The incident commander must know the construction characteristics of the building, the size of the fire area, and how long the fire has been burning. Reports from officers and firefighters coupled with the incident commander’s knowledge and observations that are assisted by any pre-fire plans will help to determine when it’s time to withdraw from the structure.

COLLAPSE POTENTIAL

All buildings have a collapse potential. The building with the greatest potential is one of unprotected, non-combustible construction. Following that type, in order of hazard, are wood frame, ordinary (brick and wood joist) construction, mill (heavy timber), and, the least likely to collapse, fire resistive construction.

Unprotected, non-combustible

In unprotected, non-combustible construction, the structural members offer no fuel to the fire. Usually, there is a system of steel columns, girders, and beams for interior support. Masonry walls may be used as bearing walls supporting these steel structural members. In other cases, steel members are the bearing members. Where steel members are used for bearing, the masonry walls may be only curtain walls. These are just hung on the steel bearing members to close in the sides of the building. The roof is usually constructed of lightweight steel formed into open-web joists that support a roof deck of corrugated steel panels which are welded to the joists. The roof deck will normally have a built-up, composition roof covering.

The prime potential danger in this type of structure is roof collapse. The unprotected, lightweight steel, open-web joists fail rapidly when exposed to fire. The time of failure is related to the fire’s intensity and the fire load stored in the building. These structures have failed in as few as five minutes.

The lightweight steel, open-web joist is spaced farther apart than standard wood joist. The spacing depends on the depth (distance between the top and bottom chord) of the joist and the load being carried. The most common spacing is four to six feet. While vertical ventilation is important in a fire, with this type of roof construction extreme caution must be exercised and may have to be avoided altogether. The wide joist spacing may make areas of the roof deck nonsupportive as cuts are being made. Horizontal ventilation may be the only alternative available. In any case, unprotected, non-combustible construction cannot survive the effects of fire without the early collapse of the roof or exposed floor decks.

Wood frame

In degree of collapse potential, wood frame buildings rank second. This type of building may be a single-family home, which includes row houses. There are any number of small retail and apartment buildings that are wood frame. The construction consists of either platform or balloon-type, each having specific problems. The structural members are combustible and subject to dry rot, decay, and termite damage. Fires in these buildings are more intense since both the building itself as well as the contents are combustible.

The contributing factors that lead to collapse and rapid fire spread in these structures are:

• Vertical fire spread via pipe recesses.
• Interior walls and partitions.
• Exterior walls between sheathing and exterior siding.
• Horizontal fire spread via common attics or cocklofts, common cornices, and party walls due to deterioration or lack of fire stopping.

In older cities where many frame row houses were constructed, urban renewal is now causing the removal of selected homes from the rows until new structures can be built. The buildings that remain standing are extremely prone to collapse during fire conditions because of the removal of lateral support from their sidewalls. These buildings, due to their age, have been further damaged by the natural decay of the wood members.

During heavy fire conditions, the rear walls of frame row houses can fall away and collapse in one section. Heavy fire in the attic/cockloft will burn through the roof supports, weakening the roof structure and causing collapse of the roof onto the top floor. Collapse of the stairs in fire conditions is not uncommon.

Photo by Ron Jeffers

Ordinary

The next type of construction most prone to collapse is ordinary (brick and wood joist) construction. This type of construction is probably the most common type construction in the country, excluding wood frame private dwellings. Ordinary construction consists of masonry bearing walls (usually brick) and wood joist spanning from wall to wall. The wood joists are usually in a direction that is parallel to the street the building is facing. Joist length is limited to about 25 feet. If the building requires a span that is longer, a system of columns, girders, and beams will be employed, or another bearing wall will be constructed to carry joists the entire length. The joists are connected to the bearing walls. The joists will have either a square cut (]) at the end (which will act as a lever on the wall if the joist collapses) or an angle cut (/), which is designed to pull out of the wall, leaving the wall intact.

During a fire, the wood joist will absorb water, possibly causing the joists to swell and subsequently to pull out of their sockets in the wall. The bearing surface that the joist rests on, the brick wall, can be weakened by water deteriorating and washing away the mortar. A look at the outside of a brick wall after a tower ladder stream has been operating will show what can happen to the brick and mortar.

Walls will deteriorate with age and often require reinforcement. This is accomplished by the use of “spreaders.” Spreaders are rods or cables designed to distribute a load between two or more structural members. The part of the spreader that you see on the wall of a building is often in the shape of a star, a diamond, an “S,” or just large washers and nuts on a rod end on the outside of the wall. If you find spreaders randomly spaced, it’s a sign of weakness in that wall. Beware of the entire building.

Mill and fire resistive construction

The collapse potential of mill construction (heavy timber) and fire resistive construction is rare. The stability of the mill constructed building is due to the size of the wooden structural members. While collapse is rare in this type of building, early collapse has taken place in as few as 12 minutes in a building that is under demolition and fully ventilated with all doors and windows removed.

Fire resistive buildings offer the greatest resistance to collapse. This type of construction has structural members that are protected against the effects of fire for specified time periods as per laboratory tests. These buildings have walls rated at four hours, two-hour floor and roof decks, fire resistive stairways, vertical shafts, and pipe enclosures. These factors limit the spread of fire, and the fire resistance of the structural members significantly lessens the probability of collapse. Should collapse occur, it will take place in a localized area and not be as extensive as in ordinary construction. Mill and fire resistive construction offer us increased periods of operational time on the interior of the building.

COLLAPSE INDICATORS

When faced with signs of potential structural collapse, the incident commander should think about withdrawing his forces from the fire building. The following are some collapse indicators:

• Two or three floors fully involved in fire.
• Little or no progress on a fire after 15 minutes of operating well placed handlines in ordinary construction.
• Little or no water run-off while using heavy streams.
• Walls bowing—loads are shifting.
• Fire visible through walls.
• Walls disassemble under stream impact.
• Failure of a section of a wall.
• Water running through brick work.
• New cracks developing and moving, and existing cracks lengthening.
• Distortion of doors and windows.
• Plaster or brickwork falling.
• Beam ends pulling away from their supports.
• Heavy stock stored on the
• floor above a heavily involved fire.
• Cracking noises that can’t be identified.
• Indicators of structural alterations.
• Buildings that have been vacant and open to the elements for a number of years.
• Large accumulations of snow or ice on roofs.

These indicators must be recognized by all fire forces and immediately reported to the incident commander. Depending on conditions, action must be taken to limit the hazard to personnel.

The factors that contribute to collapse must be constantly monitored so that the incident commander can re-evaluate his strategy and tactics to meet the situation. In just a short time, under fire conditions, the entire situation can change. At a cellar fire, in an ordinary constructed building, an examination was made of the supporting members. While charring of the floor joists was present, there were no indications of support loss. A short time later, an alert company officer noticed cracking in the floor joist. Further investigation disclosed shifting of a steel column due to contraction. This caused the girder to shift, affecting the floor joists resting on it. All firefighters were removed from the area and the building inspector was called to the scene to do an examination. The inspector and the chief made the examination of the cellar. The area then showed all floor joists bowing. The building was closed down and has not been reoccupied.

COLLAPSE

If a collapse takes place, the incident commander should have a prepared operational plan. The following is one suggested plan:

• Get an immediate accounting of all members by individual company officers and sector commanders. Each officer should make visual or verbal contact with the men of his command, and make a report to the incident commander.
• Determine the area, type of, and extent of collapse.
• Review the command chart to establish what units would have

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Photo by Ron Jeffers

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• been operating in the collapse zone or area.
• Establish a staging area (this will assist in controlling the wellintentioned but, at times, inefficient members).
• Call additional fresh resources (specialized units trained in collapse operations if available).
• Beware of secondary collapse. Delay immediate re-entry into the structure.
• Control utilities.
• Maintain radio discipline.
• Start a log of activities for control purposes and reports.

Immediate rescue

Strong leadership is required for rescue operations, which will take place after initial size-up and survey (it is not wise to leap before you look, especially in this situation).

• Concentrate on members who can be seen, heard, or who are known to be in a specific location.
• Set up an around-the-clock
• survey, get more than one fix on the location of trapped personnel.
• Once located, establish and maintain communications. If the trapped member is able, he can guide debris removal.
• Use fresh personnel and relieve working crews often.

Exploration

This is one area that should never be omitted. If you are unable to find those missing using the previous procedures, then you must search selected areas.

• Locations will be determined by the type of collapse and building construction.
• Locations to search should include under stairs, near chimneys, and in rooms where exits are blocked.
• The type of collapse will indicate where members may be located. If they were operating above the collapse, they may be at the base of a lean-to collapse or in the middle of a “V” collapse; if they were working below the collapse, they may be in the void of the lean-to or either void of the “V” collapse; if the building collapsed pancake fashion, firefighters will be between the floors if they were working underneath, or on top if they were working above.

If members are still not accounted for, begin debris removal in the most likely area that should be searched, usually the last probable known location of the missing person. The area selection is based on your knowledge and experience. Rubble and debris clearance should continue until those who are missing are accounted for.

• Establish a log and record loads removed and their locations.
• Be systematic, go piece by piece.
• Be especially careful when using power tools.
• Heavy equipment may be required (you should have a listing of your resources before an incident).
• Do not confuse this operation with that of a clean-up job. This is an important part of the plan to find those who are missing.

All aspects of the entire operation from beginning to end should be documented. After any collapse, whether firefighters have become trapped or not, a critique should be conducted. The critique will increase your knowledge of the factors of collapse and what reasonable actions should be taken. The factors of the collapse must be identified. During the critique, do not condemn any personnel. Rather, seek to train, educate, and improve their methods of operation. The following are some of the questions that should be answered during the critique:

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• Were fundamental observations of the structure made?
• Were signs of collapse recognized? Were they reported?
• Was information about the structure available before the incident?
• When did collapse take place?
• How severe was the fire? How long had it been affecting the building?
• Was there a need to have crews inside at the time it collapsed?

Determine how, when, and why the building collapsed. The lessons learned should be incorporated into the department’s training program.

The incident commander is responsible for the safety of all personnel at the scene. He must be aware of how injuries and deaths take place, which involves an understanding of building construction and the proper application of tactics. As a fire grows in size, so do the responsibilities. The incident commander’s span of control will increase in size until it is unwieldy. Therefore, the smart incident commander will delegate to various subordinates the responsibility of handling certain facets of the incident. The delegation of the responsibility for incident scene safety could be delegated to a safety officer.

SAFETY OFFICER

If possible, departments should have a safety officer respond to large-scale fires. The prime responsibility would be the safety of all personnel and equipment. The function would not, however, be limited to these two functions. The safety officer would perform the staff function of assisting the incident commander and advising in matters of safety.

The safety officer should report to the incident commander and obtain a briefing of the existing conditions. The safety officer should be aware of the burn time, starting with the transmission of the alarm. Time goes by very fast at a fire. It is important to know how long the fire has been affecting the structure. The incident commander should pass on to the safety officer any matters of particular concern that need to be attended to in the safety area. The safety officer should not be used for firefighting purposes, as such an action would nearly prevent him from performing his primary responsibility.

After being briefed and addressing the incident commander’s specific concerns, the safety officer should assess the situation himself.

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He should identify existing and potential hazardous situations associated with the incident. He should consider the degree of involvement of the building, the duration of the fire, the construction type, and the building occupancy. He should survey the exterior of the building, looking for weakened areas. The same procedure should be followed for the interior of the building. Should weakened areas be found, the safety officer should inform the incident commander.

Weakened areas shall be clearly indicated by posting warning signs or using warning tape. Units or apparatus operating in danger shall be relocated and the incident commander notified so that the command chart can be changed.

The safety officer should establish the collapse zones within which no personnel or apparatus are to be located. These areas should be fully illuminated. The size of the collapse zone will depend on existing conditions and the height of the structure. Adjoining lower buildings may be within the danger area and require immediate evacuation.

Recent collapses have disproven the theory that a wall will fall away from a building 1/3 of the wall height. The collapse of a fourstory, ordinary constructed factory left rubble up to 140 feet away. The sidewalk of a one-story building is always within the collapse zone. Units should be required to operate from the road or street if danger signs are present. Remember, firefighters have been killed while standing in front of stores several doors from the fire building. Once firefighters have been removed from the danger area and the warning signs posted, it is the responsibility of the company officers to make sure that they stay out of that area. Strong leadership is required to enforce the restrictions on many of the more aggressive firefighters. There is no excuse for allowing the needless exposure of personnel to predictable danger.

In emergency situations that are life threatening, the safety officer should exercise his authority and stop unsafe operations. In routine operations, the activities should be monitored and individual company officers advised on safety matters.

All relief personnel should be advised of the current status of the building and all safety restrictions that have been imposed on the operations.

The safety officer should investigate any serious damage to equipment that takes place in order to determine the cause and how to prevent a future recurrence. The investigation may also uncover safety problems with the equipment. A record of the investigation should be kept on file, documenting the facts of how the damage occurred. Recommendations for correcting the problem and damage should be forwarded to the department heads and filtered down through subordinate ranks when required for proper followup critique and training.