Sao Paulo, Brazil, Adds to High-Rise Fire History
A new chapter was written in the fire history of high-rise buildings in the City of Sao Paulo, Brazil. It was a long chapter in the sense that it started on February 24, 1972 and ended on February 1, 1974. And yet the two major fires that contributed to this chapter were of amazingly short duration.
The first fire started in combustible material located in a light well that opened onto the fourth and fifth floors of the 31-story Andraus Building. Department stores occupied the first seven floors, with offices on all others. From the accounts offered by occupants of the building, the fire entered both the fourth and fifth floors and quickly spread across the floor via combustible fiber ceiling tile. The speed of the fire travel can be attested to by the large number of people who were unable to escape the flames’ progress and had their clothes afire as they left the building.
As rapid as the lateral spread occurred, it appears to have been closely rivaled by the rapid vertical spread. One open stair ran from the first to the seventh floor; another from the fifth to the seventh floor. They provided an ideal media for rapid heat transfer to the sixth and seventh floors with apparent instant ignition of the plentiful supply of combustibles. It may be said that the total involvement of the fourth, fifth, sixth and seventh floors occurred almost simultaneously. This fire created a heat mass of such magnitude and intensity that nothing comparable occurring within a building and fueled by ordinary combustible material has ever appeared on the record.
Even given this tremendous heat source, it is still startling to realize the ease with which the fire spread on the exterior of the building to the eighth through 31st floors. Despite the fire loading on the upper floors due to the heavy concentrations of paper supplies expected in an office occupancy, as well as finishing and partitioning, it would still require a heat source of tremendous magnitude to involve this entire building and render the fire force helpless from the time they arrived.
The horizontal extension of the spandrel 12 inches beyond the facade of the building did not protect the 1/4 -inch plate glass windows which apparently failed quickly under the intense exposure. This failure left the upper floors vulnerable to rapid and successive involvement of their contents and furnishings—a unique fire when you consider that it traveled 24 floors. It is worthwhile, therefore, to examine the contributing factors and decide what can be done to prevent a similar occurrence, or failing to prevent it, to cope with it.
Fire loading and occupancy
The fire loading of the original floors of involvement is beyond that which we would expect to encounter in the United States or Canada. Native woods are plentiful in Brazil and are beautiful and used extensively as a wall finish as well as for partitioning and furniture. This probably also accounts for the extensive use of combustible fiber ceiling tiles on wood supports, creating a virtual lumber yard in the ceiling space.
To compound the problem, add a department store to this environment and the stage is set for a holocaust. But first a few additional ingredients must be added.
In the infancy of high-rise building design, it was quickly realized that the advantages inherent in high-rise construction also created problems. One obvious problem was that manual fire fighting was seriously limited on the upper floors. Automatic extinguishing systems had not been perfected and therefore certain design features had to be incorporated to guard against uncontrolled fire. One of these features was the compartmentation of individual floors to limit the potential areas that could be involved by fire to that which could reasonably be controlled by one or more hose lines. Limiting the combustible materials used in construction or finishing also served to limit the size of the fire.
However, limiting fire areas on individual floors would not have been effective if we allowed fire to involve more than one floor and develop a total volume of fire that once again was beyond the capability of the fire fighting forces. Therefore, vertical shafts were required to be enclosed with walls of specified fire-resistant ratings, as well as other walls and floors. All openings between floors were required to be filled with fire-resistant materials to prevent upward extension of fire.
Failure of design
In the Andraus Building the designer made the error of providing two large vertical arteries, the open stairways. Such design permitted rapid transfer of heat from the fourth and fifth floors to the sixth and seventh. Here the additional combustible material provided fuel to develop the “critical mass” of heat necessary to effect the rapid involvement of the entire building. With the rapidity of fire spread, any one of the individual floor areas of 9500 square feet (with its heavy fuel loading) would have been sufficient to provide a serious exposure to the floor above. However, when we combine the fire loading present within 38,000 square feet (total of four floors) and ignite it almost simultaneously, then we begin to understand the origin of this fire.
Another component that would appear to have been warranted in the circumstances would have been an automatic protection system. The rapidity of the spread would seem to indicate that a detection and alarm device would have been of little use, particularly in view of the limited capacity of the standpipe and water supply systems available. A properly designed automatic sprinkler system undoubtedly would have made a difference, although once again, the rapid spread on every two floors simultaneously could have overtaxed the system. In any event, sprinklers would in all probability have slowed the rate of development of the fire and affected the eventual outcome. It is difficult to understand that in the presence of so many fire-breeding conditions how those responsible for life safety in the building could have overlooked such an obvious approach to reducing the threat of fire.
Weather had its effects
If the design of the building, its contents and combustible finish were not sufficient to produce the holocaust, then the weather and the prevailing winds combined to provide the missing ingredients. On a warm 73°F day, windows were open and a fresh 17mph wind was blowing from the south. Since the fire originated in the light well on the south side of the building, the fire was in an ideal location to receive an increased oxygen supply and to have the heated products of combustion pass over the plentiful supply of combustibles to the north, accelerating and directing the spread.
It is interesting to speculate regarding the outcome, given the adverse contents and design, if the wind had been blowing that vigorously from the north. It is entirely possible that the fire front that we described would never have been formed. It is conceivable that even if the interior of the building did not become involved on both the fourth and fifth floors simultaneously, the prevailing air flow would have served to carry the products of combustion to the exterior of the building through the light shaft. This flow could have reduced the rate of spread and probably the extent of the fire.
While the direction and velocity of the wind were favorable to rapid fire development, they also provided some beneficial effects. Blowing as it did, the wind most certainly had an effect on the heat levels on the roof during the initial stages of the fire, as well as upon the quality of air. With this tremendous fire front, if there had been no strong wind blowing the fire away from the occupants on the roof, it is predictable that the number of fatalities and injuries on the roof from burns, thermal shock, asphyxiation and panic would have been much greater. Contributing to the deflection of the fire front and the reduction of the heat transfer to the roof space was the heliport parapet which extended almost 5 feet beyond the building facade and was 3 feet high. Working in conjunction with the wind, it had a significant beneficial effect on the environment on the roof during the early stages of the fire.
Another advantage associated with the wind was the forced supply of reasonably pure air that it afforded to the hundreds of people who were unable to reach the roof because of closed sliding doors and who were trapped in the stair enclosures. While many fire protection engineers and architects may disagree with the policy of including window openings in the exterior of the only stair enclosure in a highrise building, in this instance it proved to be an advantage. It is frightening to contemplate what might have occurred if the stairway had been totally enclosed without ventilation while the products of combustion from the fires on the lower floors entered the stair through damaged door assemblies and crevices. As it happened, the brisk wind not only supplied the occupants of the stair enclosure with fresh air through the window openings, but it also carried the toxic products of combustion away from the potential victims.
Another influence exerted by the wind was the effect that it had on the horizontal transfer of heat across the 98-‘foot Avenida Sao Joao to heavily involve in fire the three-story multiple dwellings to the southwest. Once again, it is interesting to speculate regarding the eventual outcome had the separation between buildings in the path, of the fire been significantly smaller, or if the buildings (with similar fuel loading) were as high or higher than the fire building. If a fire front can cause ignition at the 50 to 60-foot level aboveground across a 98-foot separation, why not at higher levels? As real estate values spiral upward and the craze for high-rise buildings continue, it is conceivable that we can have conflagrations involving multiple high-rise buildings with tremendous loss of life … unless we correct errors in design, stop overloading with combustibles, and install the necessary protective systems.
Helicopter rescue limitations
Any analysis of this fire would not be complete without reviewing the rescue of the occupants who fled to the roof. At approximately 5:30 p.m., one and a half hours after the start of the fire, the first helicopter landed and the evacuation of some 350 people from the roof began. The total effort consumed approximately four hours. In the meantime, approximately 50 people on the upper levels of the building were escorted down the interior stair to the safety of the street. The successful removal of such a large number of people by helicopter from the roof prompted many people to hail this means of escape as the solution to the life safety problem in high-rise buildings. Without attempting to detract from the heroic work of the helicopter rescuers, I think that it is important that we analyze the circumstances surrounding the rescue operations before embracing it as a valid method of fire operations for the future. First, it should be recognized from the reports of witnesses that within an hour the fire had for all intents and purposes consumed itself. And that within a scant half hour the chief threat to the occupants was the threat from panic. During its early stages when the fire front was at its zenith and when the threat to the people on the roof was the greatest, it is questionable whether or not the helicopter could have made a successful approach to the roof.
In circumstances where there is immediate need for rescue for the occupants on a roof of a building seriously threatened by fire, the reflex time (notification to arrival) for the rescue team has to be minimal if they are to be successful. Response within the time constraints that exist under fire conditions would require the services of trained helicopter personnel on an almost standby basis. Our ability to meet this commitment is questionable. This does not mean that the potential of the helicopter should be ignored, but rather that it should be recognized that it is a means of last resort.
If a building is well designed, the need for helicopter evacuation under fire conditions is practically eliminated. If the building is poorly designed, then fire spread may be so rapid and the threat to life so instantaneous that the time available for a helicopter rescue will be limited. The helicopter should be maintained available and contingency plans developed for its use, but it is not a viable substitute for stair enclosures, subdivision of floor areas, sprinkler systems or other design features.
What then have we learned from this fire? We have seen larger fires in lumber yards, bulk oil storage plants, forest fires and even possibly in bowling alleys, but never in a high-rise building. The height of the building and the helplessness of the people trapped on the upper floors when a fire of this magnitude extends beyond the capacities of the local fire departments are frightening things.
Interior egress and access are blocked both by fire and smoke and exterior access is limited by fire and the limits of the fire department’s equipment. When a lumber yard or oil storage depot burns, the supporting fuel is at ground level and located within horizontal separations in positions that can be protected. In a high-rise building, particularly one containing serious design errors, we have the unique situation of additional fuel positioned not horizontally but vertically above the original fire. Here the extension hazard is magnified and control rendered virtually impossible. The threat to life is extreme as we will indicate in the next fire we consider.
We have probably underestimated the potential for auto-exposure in high-rise buildings, particularly when we have open shafts between floors, undivided floor areas, heavy fire loading, extensive use of combustible interior finishes, and large exterior glass surfaces flush or near flush to exterior walls. When there are no automatic extinguishing systems and there is a strong wind favorable to the spread of fire, there can develop a volume and intensity of fire which can produce a substantial fire front. If this front is sufficiently powerful to extend via the exterior to several higher floors, it will take over additional fuel, add thermal input to itself and then have sufficient strength to extend to still higher floors. With this threat facing us, we have no other alternative than to continue to strive for building codes and zoning regulations that would reduce the possibilities of this recurring.
Wide World Photos
The second fire
The second incident in the new chapter in the history of tragic highrise fires was written in Sao Paulo on February 1, 1974. At about 9 a.m. a fire originated on the 12th floor of the 25-story reinforced concrete Joelma Building. The lower 10 floors were occupied for vehicular parking and were not involved in the fire. The upper 15 floors were occupied as offices with the typical paper supplies associated with banks and similar businesses. These upper floors consisted of two irregularly shaped wings fronting on intersecting streets and interconnected by a common elevator lobby. There were no subdividing partitions or fire doors separating the wings of the elevator corridor. In fact, there was one large interconnected area of an irregular shape with multiple facades. A single, unenclosed, interior stair located in the elevator corridor provided the only means of egress from the building.
There appears to have been a delay in reporting the fire and there was no ready means (interior alarms) for notifying the occupants of the upper floors. When they were finally notified, in all probability passage to the street was impossible due to the contamination of the only stairway with heat and smoke. With very few options to choose from, approximately 80 people went to the roof, while the remainder of those trapped fled to exterior positions on exterior ledges to await rescue. In most cases they waited in vain. The people who fled to the roof were probably encouraged in part by the reports of the rescues that were effected in the Andraus Building in February 1972. Unfortunately, while there were some similarities in the two fires, they also differed significantly. It was these differences that led to the loss of life on the roof.
In the Joelma fire, although the building eventually became fully involved in fire, the development of the fire differs markedly from the Andraus fire. In Andraus we experienced an almost simultaneous ignition of the four floors of a department store and the massing of individual fires to form a unique fire mass that simultaneously exposed and involved multiple floors above the originating fire floors. In a very short time interval the entire building was burning. In Joelma, the original fire started on one floor and spread horizontally to consume that floor area and to develop the impetus to spread via the open interior stairs to the floor above. This process was repeated from floor to floor. The spread appears to have been primarily via the interior particularly during the initial stages of the fire. As additional floors became involved, the cone of the fire grew and the intensity of the heat progressed to the point where the exposure to the upper floors on the exterior of the building contributed significantly to fire travel.
In any event, the total involvement of the office section of the building required a longer period of time to take place than in the Andraus fire. The extension of the fire seems to have occurred by a sequential ignition of the upper floors on a floor-by-floor basis rather than simultaneous involvement of multiple floors.
Wind as a factor
The wind conditions at the Andraus fire served to influence the direction of the fire and provide essentially a one-front fire. As pointed out previously, the wind also helped transfer a good deal of the heat from this fire front away from the people trapped on the roof. At Joelma, there was no wind to influence the fire in this manner. In its absence the fire progressed and developed its own air currents. Each floor, with abnormally high fire loading to support a major fire of its own, became fully involved and discharged fire, heat and smoke through almost every exterior wall opening. Given the multiple facades on the irregularly shaped Joelma Building, it produced a wall of heat and flame on every side of the building that virtually surrounded the occupants and then enveloped them in superheated air.
There were two other differences in these fires. The top three floors of Andraus were unoccupied and therefore the fire loading associated with the partitioning, contents and finishing was not present to increase the exposure and the threat to life safety of the people trapped on the roof. In Joelma, the building was fully occupied and the upper floors became fully involved and generated a maximum exposure.
As mentioned previously, an extension of the roof surface—approximately 5 feet beyond the exterior wall of the building—deflected the heat from the fire front away from the roof. Unfortunately, openings in the parapet wall surrounding the roof of Joelma were designed in a way that deflected the heat from the fire fronts toward the center of the roof, increasing the threat to trapped people. The roof was approximately 2 inches of reinforced concrete. On top of the poured concrete a wood frame structure covered with a corrugated composition siding was superimposed (probably to provide an air space to obtain an insulating effect). While the heat was not sufficient to burn the wood supports, it was more than the human body could endure and 80 people lost their lives when rescue efforts failed.
Helicopters made inoperable
The primary rescue effort at the roof level consisted of repeated attempts by helicopters to reach the victims. But the conditions in the vicinity of the roof were not favorable to a helicopter landing because the updraft created by the fire adversely affected the ability of the pilots to maneuver. Further, the products of combustion diluted the oxygen content in the air to the point where the internal combustion engines were unable to fire properly and the pilots ran the risk of stalling out.
The victims waited in vain and this experience raises a point that places the helicopter in proper perspective as a rescue device during a serious fire. When a fire develops in a high-rise building to the point where it cuts off the escape of a large number of people and seriously threatens their lives, the conditions around the building will make it difficult, if not impossible, to approach the building for landing. Updraft, heat, oxygen reduction, poor visibility (smoke), and toxicity of products of combustion all work against the use of helicopters when you need them most. Furthermore, this is a good time to repeat the principle that the time and place to ensure life safety in high-rise buildings is during the period that the building is being designed. If buildings are designed correctly, you will not need helicopters and if they are not designed right, it is unlikely that helicopters can compensate to any significant degree for the errors in design.
Design errors take blame
The designers of both the Andraus and the Joelma buildings showed a lack of appreciation for the basic principles of fire safety design. The single means of egress, coupled with the absence of a standard enclosure in one instance (Joelma) and the negating of the benefit of an enclosure in the second instance by the use of a hollow core wooden door as an opening protection (Andraus). The open floor design contributing to the rapid horizontal spread, the extreme fire loading and the absence of a suitable warning system and evacuation plan are all examples of errors common to both buildings.
In spite of these omissions, the fire in the Joelma Building provides an excellent case study of what an elementary understanding of the principles of fire threats in high-rise buildings could have accomplished if they were known and used. As stated before, the main problem associated with the protection of life from fires in high rise buildings is the limitation of the size of the fire. Public fire protection services can usually contain a fire in an elevated portion of a building if the fire area is limited to 5000 square feet or less. If the horizontal spread of the fire exceeds this limit, the heat developed will also increase the risk of vertical spread. If the building contains open vertical arteries, then a tragedy can be expected.
In Joelma, both the spread in a vertical and horizontal direction could have been avoided if a simple precaution had been taken. The two wings of the Joelma Building were interconnected by a wood-lined corridor that also contained the open interior stair. If self-closing fire doors or doors which were designed to close upon the activation of a detection device had been located at both ends of the corridor, they would have accomplished two objectives. First, they would have impeded the spread of the fire from one wing of the building to the other and thereby limit the amount of heat developed for vertical transfer and fire extension. Secondly, they would have isolated the open interior stair from the fire area and allowed its use for egress by the occupants of the upper floors. Of equal importance, it would have deprived the fire of a means for rapid vertical spread.
This reduced area of involvement and consequent reduction in heat generation plus the absence of an interior open stair for rapid vertical fire travel would have greatly reduced the possibility of major involvement of the building. Extension via the exterior of the building would still present a problem, but it is unlikely that the fire or the loss of life would have been as great as it was.
Fire fighters stymied
A word must be said regarding the efforts of the Sao Paulo Fire Brigade. Initially, they were at a disadvantage due to the delayed alarm and the heavy traffic which obstructed their response. On their arrival the extent of the fire was beyond the capabilities of the strongest fire department in the world. The Paulitos were further handicapped by the absence of an interior enclosed stair from which to operate, a small-diameter, totally inadequate single-riser standpipe system, inoperative elevators and a public water supply system that has a flow of approximately 100 gpm. Water tankers are the major source of water supply and they can hardly be expected to support the master streams required by a fire of this magnit ude.
The fire force is small, consisting of 1300 officers and men in a city of over 5 million people. Their exploits at this fire demonstrated that they attempt to substitute courage and heroism for what they lack in fire protection systems and physical equipment. They used ropes and ladders as improvised bridging between buildings regardless of the distance to be spanned and heedless of their own safety. Fire fighters were dropped to roofs, from helicopters that were unable to land, in an attempt to rescue those who were trapped and to bring them first aid. They are a well-trained, physically fit, disciplined group of men. The tragic results of were not due to any lack of effort on the part of the Sao Paulo fire fighters. The situation was beyond human control.
Editor’s Note: Commissioner O’Hagan was one of a group of fire experts invited to Sao Paulo in March of this year by the Brazilian Government to conduct a symposium on fire protection in high-rise buildings. While there, he investigated the Andraus and Joelma fires.