BY GERALD R. TRACY
When any type of building is designed and assembled into a structure, there exists a compromise of trust. That trust is the confidence and tacit agreement linking the architects, builders, occupants, and firefighters in the belief that every edifice constructed is designed and erected with diligence to ensure occupants’ safety while inhabiting the building and firefighters’ safety if called to suppress a fire in that building.
When early man first emerged from wind-protected areas and caves, he began to construct shelter for security and comfort. He brought fire with him once he realized how to harness its life and energy. The wonder and danger of fire have been with us since man stood upright. Early man soon learned that fire could protect and maintain his survival or destroy it. His existence was less complicated but not trouble-free.
As man has evolved over the past many centuries, our existence has become much more secure, but it continues to be increasingly complicated. So many responsibilities that affect our very lives have been delegated to individual professions. The professionals that are the focus here are the creators, the architects, who begin by building castles in the sky-those individuals who have envisioned a thought and then drafted the many ideas that became the skyscrapers that have developed our spaces and our skylines.
We have evolved far from the cave, and we still have kept the fire that man brought with him. Now thousands of years later, we have harnessed the energy of fire to do much for our existence. We now use the byproducts of energy to form the elements that fashion and support almost every detail of high-rise structures. It is the byproduct of heat that forms steel, creates steam to turn turbines that generate electricity used at construction sites, and produces the energy in combustion engines that mix and transport concrete. It is the heat of energy that plasticizes steel to be formed into the shapes of support, and it’s that same heat that will return steel to plastic again. Heat will not transform concrete into plastic, but it can affect its strength and has caused moisture within to compromise and fracture its integrity.
Both of these elements of construction, steel and concrete, are used to erect high-rise buildings. With the advancements of technology, architects, with the help of computers, are able to calculate the strengths of these materials to their maximum influence with the minimum of substance. It is my contention that the equations being used are flawed. The computer is only as smart as the information we give it. The result of the equations being used may be as irrational as the thoughts of terrorists that also influence our everyday existence. All of us on this planet have had to alter our lifestyles because of that reality.
DISPUTING DESIGN STANDARDS FOR SUPPORT
To elaborate on my contention that the equations used to calculate the strengths of steel and concrete are flawed, I am disputing the design standards established for the strength of support. I believe the standards do not account for the assault to which these structures will be subjected should they be exposed to the heat of fires from today’s typical fire loading. The required standards in today’s building codes meet the requirements of gravity; support for the projected live and dead loads; any superimposed weight, including the height of the structure; and, of course, strength against the lateral loads inflicted from wind.
The scale or equations used must coincide with the rapid and extreme assaulting temperatures from the types of furnishings and equipment we place in these structures in this new millennium. The requirements as written were based on the standards of the fire loading of more than 50 years ago! Fires involving those fuels developed their temperatures at a much slower rate than today’s fuels.
The National Institute of Standards and Technology has performed live burn tests with the fire loading of a typical office cubicle, and the cubicle completely flashed over in less than five minutes. The cubicle partitions offered by office supply manufacturers and distributors are treated with fire retardant chemicals, but they will burn when exposed to flame and will allow fire to communicate. The fires of today grow at lightning speed. The building and fire codes used across the nation with respect to high-rise office buildings regulate the flame spread and generation of smoke by materials used as furnishings and floor and wall coverings, but human nature brings with it its own supply of decorations and artifacts that add to the fire problem.
The structural elements of these buildings are being exposed to the extremes of heat in time frames that can be considered immediate with respect to annealing or heat rendering. That implicit trust we expect from architects is wanting. The diligence of the builders who construct these monoliths to adhere to plans and performance is now more profound because the blueprints are inked to an exact moment of strength or failure with less range of safety.
The fire service has understood that past performance and application of fire protection with sprayed-on coatings have been questioned for the past few decades because of its deficient performance in high-rise fires. Up until September 11, we had not experienced a total failure of a high-rise building; it was only a matter of time. We would all agree that the circumstances and compromise in the twin towers could not have been incorporated into the original building plan, but what should heighten everyone’s attention is the resulting failure and collapse of the Seven World Trade Center building.
This structure was also unique in design. It was not built of the same characteristics as the towers, which were referred to as tube-type construction. Building #7 was a framed-steel structure built to resist excessive winds. Its design included two-story-high trusses, one at the seventh story and one at the 22nd story. This was a perimeter moment-resisting frame, the connections of which would endure greater loads of force and stress.
A wind tunnel study of the proposed site with the towers in place revealed forces greater than the local codes indicated, so this structure had to be built with a design to withstand the increased stress. It was also unique in that it was built with a braced core supporting the building and cantilevered above spaces that existed below. These spaces existed before construction and consisted mainly of an electrical substation; other problems involved existing subways and truck ramps to the twin towers. The structure was built and occupied by early 1987 and was expected to stand erect for centuries. That obligation was not fulfilled. The structure failed, and it failed from exposure to fire and the typical fire loading within. The building withstood the assault of fire for many hours, and it can only be assumed which elements of support were affected and ultimately failed.
Many are quick to argue that a storage tank of diesel oil became involved and fueled the fire in an area that was critical to the support of the structure, but it cannot be proved-only speculated on. Even if that speculation is accurate, where is that confidence of trust?
It is my contention that the structure failed from the fire fueled by the typical fire loading existing in the structure on that very day. The calculated equations of strength are lacking further still for the fact that the workforces that construct these buildings are human and are subject to error and oversight. The design calculation used before the days of computers included an increased margin of error that could account for this.
If humans didn’t occupy this planet, then the fire service would have no need to exist. I am referring not just to providing the services of fire suppression and protection but also the many other customer services we provide because of human error. The fire service and the public who occupy these buildings are the beneficiaries of consequence as a result of any deficiency. Understanding this, do we need to adjust our approach to high-rise operations?
Well, we need to make more than a few adjustments in mindset and education. We not only must educate ourselves but also the authorities that influence and establish building codes. In that respect, we must have a loud and clear voice. That can be accomplished only if all in the fire service are on the same page and in accord. We can all agree that the laws of physics are the same anywhere on the planet. We should all agree on the challenges of attacking fires in high-rise structures because that’s where we begin to differ in concept.
Many departments across the nation that have little experience with high-rise firefighting operations use a tactical approach that is successful for structures other than high-rises. Much of the American fire service uses small-diameter hose for structural firefighting and is quite successful when the quantities of water being applied to the burning fuels are appropriate-that means that it works well for confined and less advanced fires but not for advanced fires.
What these departments fail to realize and evidently disagree on is that the typical fire loading of today generates tremendous amounts of heat (Btus) and that if our suppression operations do not effectively absorb the heat, then the structure will! The facts are that the structural elements of these high-rises are capable of failure. If we do not employ appropriate strategies and proper equipment for suppression, we are setting the stage for disaster! We should not expect that suppression teams attempting to approach fires with the limited flows of small-diameter hose will get close to the source of burning fuels to accomplish extinguishment. If that is not possible, then the structure will be subject to the inefficiency of our efforts. If the structure is also occupied, especially above the fire operations, then the public is also subject to our inefficiency.
Architects are now debating the existing standards and design of egress, alluding to the fact that occupants should have adequate facilities for exiting a structure in a shorter time frame than the current one. Is that truly possible? The fire service has long challenged that philosophy. When fires are on the lower floors of a high-rise structure, if the implementation of operations were to be halted until complete evacuation were accomplished, the fire would be allowed to gain proportions that would grow beyond the extinguishment capabilities of the arriving forces and weaken structural stability during that time.
Over the years, the architectural community has compromised exit designs and reduced the safety aspects once realized. The interpretation of having more than one means of egress has been bastardized by designing exits in a core design that meets code requirements but in effect are not truly remote from each other. The exits meet the travel distance of exit, but a person must negotiate his way back to the core of the structure to reach safety. An exit in the opposite direction is not offered. In high-rise residential occupancies, the two means of egress are exterior of the living spaces, meaning a person must be able to exit the apartment to reach an exit. Most apartments are designed with the kitchen facilities at or near the apartment entrance door. Statistics reflect that many fires originate in residential kitchen areas. Because of this fact, egress may be blocked by fire-negating access to the only means of egress (let alone a secondary means of egress).
Architects have phased out the design of fire towers (smokeproof stairwells) as exits because of the added space required for the intermediate vestibule and smoke shaft. This space has been calculated to generate increased revenue for profits rather than insurance against life safety. The fire service has requested that increased safety be designed into exits and the enhancing of the safety and operation of elevator shafts. Pressurizing stairwells and elevator shafts with the incorporation of elevator vestibules at each landing would not only enhance occupants’ safety within high-rise structures but would also add to firefighters’ safety and efficiency.
When we must respond to the upper portions of high-rise structures, it takes more time to place our members in a position to operate. If elevators are not available because their use or safety is compromised, firefighters must ascend by the stairs, which is difficult, especially when transporting the tools and equipment needed to accomplish our task. We expend a great amount of energy and must provide for a recovery period so we don’t overtax our body.
The fire service has been extending itself to the maximum for many years, and it is unreasonable to expect that that will continue or that it should be taken for granted. The world is beginning to understand our burden. That understanding should be reflected in building codes that dictate safety design requirements in high-rise structures.
The administrators who determine how many firefighters are sufficient to perform our task need to be reeducated in the challenges of today, not only relative to high-rise firefighting but also to every type of structure fire.
And, the public must support us. They all witnessed the sacrifice and dedication given on September 11, and they have expressed their sympathy and charity with donations. It’s time they accepted the increased cost of our service and the cost for enhanced safety designs for every type of structure built to be occupied by people.
GERALD R. TRACY is a battalion chief with the Fire Department of New York (FDNY), assigned to Battalion 49 in northern Queens. He is formerly the unit commander of FDNY Squad 18. He is an instructor for the department’s Captain’s Development Course and Firefighters Professional Development Program and was one of the developers of the Back to Basics training course. He lectures extensively on various topics, including strategy and tactics in high-rise structures, multiple dwellings, hotels, and private dwellings. He was a lead instructor for the FDIC 2000 H.O.T. evolution “Engine Company Operations: Standpipes.”
