BY FRANCIS L. BRANNIGAN, SFPE (FELLOW)
The construction magazine Engineering News Record tells the story of the demolition of a post-tensioned concrete building in Key Biscayne, Florida, that had been damaged by fire while under construction.1 I talked with Chief John Gilbert of the Key Biscayne Fire Department about the fire. I have been preaching the hazard of post-tensioned construction for 30 years and have the feeling that many in the fire service haven’t listened too hard. However, I am happy to report that this case is “by the book.”
In April 2000, a fire developed outside a post-tensioned, 12-story high-rise under construction in Key Biscayne. The fire extended to combustibles such as falsework and formwork in the building. Gilbert said that, well aware of the hazard of this type of construction, the fire department immediately went to a defensive attack on arrival. After the fire, no contractor would take on the job of shoring up the dangerous building. This should be a warning to those who tell me, “We always start with an aggressive attack and then back down if circumstances indicate.” In the case of tensioned concrete under construction, such tactics might lead to an urgent call for an urban search and rescue unit to recover bodies.
The fire was in one of three sections of the building, but structural engineers recommended that all three sections be demolished. This was accomplished after very careful planning by Controlled Demolitions, Inc. (CDI), a company with much experience in using explosives for demolition.2
Pour strips, areas between cast sections that are devoid of concrete to permit tensioning of separate sections, exposed the anchors to the fire. Cold drawn steel cables such as those used in tensioning concrete totally lose their tensile strength at 800°F (less than the temperature of a self-cleaning oven). The actual fire damage area was limited, but the initial damage triggered progressive collapse on several floors. Bear in mind that the vertical reinforcing rods in concrete columns are load bearing. Green concrete spalled off and exposed the rods, which then buckled out. Such a condition, should you ever see it, calls for immediate evacuation. Overloaded beam sand floors may sag and give warning, but column failure is “sudden and catastrophic.”
CDI developed an OSHA-compliant plan to install temporary shoring, which took six days. Because of the damage to the building, the demolition was very complicated. An important consideration was not to damage the foundation piles, which were needed to rebuild the building. The demolition was successful.
Post-tensioned concrete buildings are different buildings from Day One. Never use a core drill on the floor. Never use a torch to cut a stressed tendon, which is under very high-tensile stress. Cutting the tendon would release it like a giant whip. Since powerful interests have stopped the idea of marking such buildings, it behooves fire departments to identify such buildings in prefire plans.3
THE BEVERLY HILLS SUPPER CLUB FIRE
This is the second fire that caused a major loss of life that I believe has been incorrectly described. In May 1977, the Beverly Hills Supper Club in Kentucky burned and caused 164 deaths. A plaintiff’s attorney managed to assemble “experts” who testified that the deaths were caused by the inhalation of fumes from electrical insulation. A number of “deep pockets” were tapped. I did not get involved until a company that manufactured the imitation leather on the bar, which never burned, was sued in the so-called second tier of defendants and engaged me as an expert.
I studied the circumstances of that fire extensively. The statements the Kentucky State Police gathered from survivors the night of the fire provided the best evidence. Survivors told of fire around the edge of the ceiling of the Cabaret Room that was followed by dense, black, choking smoke coming down from the overhead. This and other evidence convinced me that the cause of all but two of the deaths was the burning of the combustible metal deck roof of the Cabaret Room.
The initial investigators discounted the possibility of the fire’s moving through the voids from its point of origin at the front of the building because the voids were cut up by walls. It is true that the roof was pierced by parapeted walls. The building had had many additions; undoubtedly, there were penetrations through the walls. The metal deck roof fire does not need a big opening. A tongue of flame passing through a small hole and impinging on the metal deck of the next section would be sufficient to extend the fire. (Factory Mutual tests on metal-deck roof assemblies have shown that it takes only five minutes of 8007F heat impingement on the surface of steel decking to start a self-sustaining roof fire. This fire is independent of the original fire.)
It is not at all clear whether the loss of life would have been substantially reduced if the supper club building had been sprinklered according to the usual practice, in which the void would be regarded as “noncombustible” and left unsprinklered. Since it was above the ceiling insulation, a separate dry-pipe system would have been required to prevent freezing. Of course, had code requirements for exits and fire resistance (a fire-resistive structure would not have had a metal deck roof) been met, fewer lives probably would have been lost.
I presented the proposition at a grueling deposition by the plaintiffs’ attorneys. I showed the movie of the Factory Mutual metal-deck tests. Even though I could not present them in court because I could not authenticate them, the plaintiffs’ attorneys offered my client a very modest settlement, which made it very worth their while to accept. The metal-deck roof never made the record, and the erroneous version of “fumes from plastic” has become gospel. This indicates a serious deficiency in our legal system with regard to determining the facts of a major fire.
Civil suits are often settled on the basis of potential costs. Many times, the plaintiffs are sworn to secrecy, so the facts never become public. Criminal prosecutions may fail because of defects in the handling of vital evidence or the reluctance of juries to convict underlings who were “only following orders.”
The British system of the Tribunal of Inquiry is different. Its purpose is to determine the facts. It can be assisted by experts and has the power to place witnesses under oath.
In 1983, 49 teenagers died in a fire in a Dublin disco. The Irish government convened a Tribunal of Inquiry to determine the circumstances. The ceiling was of mineral tile. The built-in banquettes and the wall covering were of plastic. An expensive, unprecedented re-creation of the fire, commissioned by the Irish Government at the British Fire Research Station at Boreham Woods, showed how the wall covering caused a fire in a foamed plastic seat to spread almost explosively. The movie Anatomy of a Fire shows the “unbelievably” rapid spread of a fire in such an environment.4
FIRE TESTS OF INSULATED ROOF DECK: UPDATE
Following my writing on steel sandwich panels in Ol’ Professor (July 2000), I came across an important study that included large-scale fire tests on roofs insulated with various foam insulations. The study “Safety of Various Insulated Roof Deck Constructions,” authored by Dr. Vytenis Babrauskas, formerly with the National Institute of Standards and Technology (NIST) and now running the independent fire safety research/ consulting firm Fire Science and Technology, Inc., and Diane Daems and Rachel Berrier, distinguished between thermoplastic and thermosetting foams and emphasized the importance of protecting thermoplastic foams used in metal deck roof construction by a thermal barrier.
It was determined that thermosetting foams did not need special thermal barriers (such as gypsum board placed on top of the metal deck, below the foam). Because of the potential for a fire to develop quickly underneath roof decks using unprotected thermoplastic foam, this construction was not allowed in most parts of the country.
Recently, however, some building codes have permitted the use of thermoplastic foams without thermal barriers. There is no way a fire officer looking at the top of or underneath a roof construction can determine what kind of foam is used, if it is thermoplastic foam, or whether a thermal barrier exists. Thus, it becomes essential to identify the construction during prefire planning. If thermoplastic foam is used and no thermal barrier is present, you would have to consider the possibility that an unexpectedly fast fire could develop during an interior fire attack. For more information, contact Babrauskas at fsti@accutek.net.
CHURCH CONSTRUCTION AND HAZARDS: COMMENTARY
In “Preincident Intelligence: A Case History” (Fire Engineering. May 2000, page 87), Eric O. Bachman relates how a newly constructed church complex could present dangers and even an impossible problem for the fire department. Dealing with church authorities can be as difficult as dealing with scientists. Despite all evidence to the contrary, church people often seem to believe that they have some divine remission of the laws of chemistry and physics because of their good work for humanity. Scientists, often positioned as opponents of religion, similarly believe the efficacy of their work for humanity will protect them from fire. I speak from experience in both fields. There is often denial of what should be obvious and resentment of interference by “outsiders.”
Reasons for the Problems
In wrestling with church people, I would ask, “What would you think if Pastor Jones announced he was going to step off the balcony and would be sustained by his faith?” The rational answer would be “I would see to it that he was restrained until he could be treated for his serious illness; he is defying the immutable law of gravity.” Gravity is immutable; it acts instantly. (I like Battalion Chief (ret.) John Mittendorf’s observation: “Falling debris has the right of way.”)
The problem is that fire is a matter of probability. Many people simply won’t admit that a fire could occur in their facility. The odds are usually on their side. I can recall only a very few times when a fire that I anticipated and for which I had preplanned actually happened.
Once in a while, there is a convert. Some years ago, Harold (Bud) Nelson, SFPE (Fellow), had to fight with the curators of the Smithsonian Institution (which in the past sometimes had acted as if it had the rights of a foreign embassy) to install an oversized fire door. They wanted an “unobstructed vista.” When a very costly fire occurred, the fire door saved the Star Spangled Banner and the National Stamp and Coin collections. I attended the meetings after the fire and sat next to the man who led the opposition to the doors. Toward the end of the meeting, I commented to him about the obdurate person who nearly killed the fire door. He said, “I’m that person. I have learned in these meetings that if you build a building to last 75 years, it will suffer a major fire; therefore, a fire should be a design consideration.”
If we could only get those we are trying to convince to adopt that attitude. Some years ago, curators at the National Gallery of Art learned that the Smithsonian was installing sprinklers and demanded the return of artworks it had loaned to the Smithsonian. Smithsonian curators, convinced by their fire, talked them out of it.
People who claim to be religious show little regard for a firefighter who might run out of air and become trapped in a hallway should a fire occur. A little sign on a door indicating the floor and stairway number might help the firefighter escape or make others aware of his exact location. [The Worcester (MA) Warehouse report on the NIOSH Web site illustrates one sad example of such a situation in which the firefighters were not able to identify their exact location.] The church opposed the posting of the sign because of “aesthetic reasons.” My reply would be, “There is nothing so unaesthetic as a dead firefighter. Our efforts in this building will, therefore, be conducted to ensure a maximum of safety for firefighters and a minimum of concern for the property.” If church officials had adequate concern for life or property, they would have sprinklered the entire property. It is about time that firefighters begin to lay down the conditions under which they will risk their lives in the face of indifference to their safety.
Church Construction Features
The church in the article mentioned above had steel-studded walls, which, from a photograph, appear to be covered with sheathing, no doubt combustible. The church had a masonry exterior, most likely masonry veneer. Veneered masonry depends completely on the building’s basic structure for stability. The light steel studs will distort by elongation if subjected to fire, which may cause the veneer to collapse. Veneered brick is just as hazardous as structural brick.
The gymnasium has a steel-beam roof, presumably of lightweight bar joists. If the gym had the usual wooden stands, there would be enough fuel to collapse the roof. If it had folding stands, which often have urethane seats, fire growth is a hazard. A pile of such chairs led to a five-alarm fire in a hotel.
Another consideration is whether anything combustible, such as fiberboard, was inserted into the walls to suppress sound. A New England high school with this construction feature was destroyed. To provide resilience, gym floors are often built in several layers.5 The corrugated metal walls raise the question of whether the walls are insulated and, if so, what material was used.6
Most probably, the floor is of wood truss or wooden I-beam construction, or a combination of both. A fire that starts in or extends to the floor voids would be extremely difficult to fight. The standard tactics of pulling ceilings and directing hoselines upward may not work because of obstructions in the void. I would recommend piercing nozzles to get water into the void without providing the fire with the oxygen it needs. Pulling the ceiling may cause the carbon monoxide in the voids to explosively ignite.
In a fire in a similar type of church building, several backdraft explosions were violent enough to blow down 1,400 pounds of wire lath and plaster and push firefighters down the stairs and out the door. As often happens, light smoke suddenly turned to impenetrable black smoke. A defective light fixture was enough to set fire to a wood truss floor and collapse it. Over the years, the wood would have become thoroughly dried out and thus would be easily ignited.7
The Building Department may point out that the floors are “rated fire resistive.” This rating is achieved in an inadequate en-durance test that erroneously assumes that fire will attack only from below the floor. It totally ignores the fact that fire can and does burn down into the floor and that defective wiring can cause fires to start in the void. The gypsum sheath becomes a detriment once the fire is behind the sheath.8
Fire can reach the “lumberyard” in the attic through the voids or can extend through internal voids or externally by entering through vents along the soffit. It is almost impossible to stop the fire from entering the roof from the floor below. Falling truss members are dangerous, and collapse is fatal. If the fire self-ventilates a nice big hole and if a tower ladder can be placed advantageously, it may be possible to get into the hole and direct a stream in each direction to hit the fire. It is most likely that it will not be possible to completely hit the fire in the roof. Based on my study of garden apartment fires, I would consider not using ladder pipes on the attic. They are ineffective and only increase water damage below. Let the roof burn off. Then, firefighters standing ready outside can rush up the stairs without fear of a roof collapse and can take care of any fire on the top floor, or they could use the tower ladder and selectively hit the fire close up.
Sunday School
One aspect of a fire when the church is occupied is that children may be separated from their parents for Sunday School classes. If a fire occurs at that time, frantic parents will be all over the building searching for their children. Does the church hold fire drills for Sunday School with a predetermined safe location for the children so the parents can know where to go to get their children?
I would write to the officials, point out the fire protection deficiencies and limitations of manual firefighting, and urge them to take fire prevention precautions seriously. A senior staff member should be appointed as fire safety officer. Because a “smoke odor” might indicate a growing fire in the voids, it is most important that the church have and follow an ironclad rule to “Dial 9-1-1” at the first indication of smoke or fire. It is a fire department’s function to determine whether smoke is hostile or friendly. There is no such thing as an “unnecessary alarm.”
Command
The ideal command and control of operations at an advanced fire in a church building requires a substantial number of people. Fire companies that would be involved in mutual aid should hold officer meetings to discuss how command should be set up. This cannot be left for the time of the fire. For interior operations, several sector officers would be needed-certainly, one on each floor and one for the gym. A safety officer should be designated. He should have an aide whose sole job is to monitor the tactical channel for any message, however faint, indicating firefighter(s) in distress. A command officer should be on each side of the building, and an officer should be appointed to serve as liaison with other agencies such as police and the structure’s management. A capable person should be assigned to record the times of major events. A RIT or FAST is a must.
Tell the Management
It is probably impossible to provide enough personnel to set up such an organization. I would send a letter to the management indicating how difficult it would be to assemble the staff that would be required to handle the manual suppression of a fire in its facility and, consequently, the firefighting effort may not succeed. Explain that you will do the best you can within the limits of keeping your personnel safe.
If a fire should occur, the current management may not know how the original management created the problems. If the building goes down in a fire, never say “we lost the building.” Management lost the building.
BUNDLE STRAPS POSE HAZARDS
As pointed out by Captain Joseph Russo in WNYF (Fire Department of New York, Issue 2, 2000), be aware that plastic straps on merchandise bundles might melt and cause the merchandise to fall to the floor. This hazard, believe it or not, was introduced deliberately so that the bundles would collapse to increase the efficiency of the sprinkler’s discharge.9 Don’t forget that the basic fire loss management policy of warehouses and warehouse stores is to have adequate insurance. Don’t get firefighters killed trying to do the impossible.
SANTA CLAUS IS COMING TO TOWN: REMINDER
As the holiday season approaches, keep in mind that a fire involving a Christmas tree can spread more quickly than many anticipate. One incident that broke my heart occurred 10 years ago on December 22 at 11 p.m. A Christmas tree erupted in fire in a home where a family of nine resided. The father attempted to get the flaming tree out of the house. The mother called the fire department and removed one child. Both were injured. The father abandoned the burning tree and attempted to rescue the other six children. He and the six children died.
Just how dangerous a fire involving a Christmas tree can be is evident also from an incident that began as a demonstration for the media and ended up as a serious accident (this was fully discussed in Ol’ Professor, November 1998). In this case, firefighters set a Christmas tree afire in an abandoned house. TV camera crews were invited to photograph. The fire grew so rapidly that one of the camera crew was critically injured; two firefighters and one cameraman were reported to be in fair condition. Apparently, the camera crew members became entangled in video cables. Part of the preparation for such a demonstration should include, at a minimum, marking and maintaining a clear retreat path and the practicing of a “bailout” drill.
Endnotes
- “Implosion Spares Foundations,” Nadine Post and Richard Korman, Engineering News Record (ENR), June 12, 2000, 12-13, and phone interview with Chief John Gilbert.
- Controlled Demolitions, Inc., specializes in the demolition of buildings by implosion. One of its engineers remarked, “We just blow out the supporter. Gravity does the rest.”
- For additional information on post-tensioned concrete, consult Building Construction for the Fire Service, Third Edition (BCFS3), National Fire Protection Association, 330,339, 347, 354-357, 369-371, 377-378.
- “Investigation into the Stardust Disco Fire Dublin,” D. Rashbash, Fire International, April/May 1984, 34-35, 38-39.
- “Lumberyard in a Gym Floor,” J. Curtis Varone and Paul Wentworth, Fire Engineering, July 1992, 39-44.
- For additional information, see Ol’ Professor, Fire Engineering, July 2000.
- “Landmark Church Lost to Fire,” Char McLear, NFPA Journal, May/June 1999, and Ol’ Professor, Fire Engineering, Jan. 2000, 111.
- For additional information, see BCFS3, 538-541.
- See BCFS3, 627.
FRANCIS L. BRANNIGAN, SFPE (Fellow), recipient of Fire Engineering’s first Lifetime Achievement Award, has devoted more than half of his 57-year career to the safety of firefighters in building fires. He is well known for his lectures and videotapes and as the author of Building Construction for the Fire Service, Third Edition, published by the National Fire Protection Association. Brannigan is an editorial advisory board member of Fire Engineering.
