Building Codes for the Fire Services
In the recent Charleston, South Carolina furniture warehouse fire, nine firefighters perished apparently by compromised and structural collapse of the building’s roof.Every year, fire related accidents caused by building collapse; flashover and deadly smoke have been the leading causes of injuries or deaths of firefighters all over the United States (Dunn, 2007).Most tragic was the World Trade Center Twin Towers’ collapse where 343 members of the Fire Department City of New York (FDNY) perished died fifty-six minutes after the attacks (Fema’s US Fire Administration, 2002).
The building officials, fire department, architects and engineers did not anticipate that such an attack could happen in American soil.
In the light of these developments, the public called for a review of all existing building and fire codes in the country. Dunn (2007) enumerated three most deadly situations in firefighting history where the ten-year study of the National Fire Protection Association indicated them as the main causes of injuries and fatalities of firefighters. They are collapse, flame spread and smoke.
“The most common types of collapse that have injured and killed many in the line of duty were floor collapse, roof collapse, wall collapse and ceiling collapse” (Dunn 2007). It is imperative that firefighters have the basic knowledge on the behavior of buildings while being engulfed in flames. What they know could save their lives when they take the risk of controlling the situation. It is also important to look back at previous strategies on how buildings were deemed “fire proofed” and considered safe at all times.
To avoid a repeat of the tragic incidents, regulatory bodies, engineers, the academe and other professionals pit their wits and talents to ensure building safety standards are met. It is undeniable that some of the codes have become obsolete with the introduction of new building construction technologies. The Need to Overhaul Existing Codes Traditionally, the safety of buildings has been regulated by codes all over the country.
Since the 1800’s the safety of buildings had been mandated by these codes and they include the use of “fire resistive materials, compartmentation features, and later, installation of automatic sprinkler systems and automatic fire alarm systems. ” (Solomon and Hagglund, 2001, p. 619). All of these prescriptions were intended to ensure building safety even in the event of a fire. These also purported to make tall buildings safer. These had worked well under hazardous circumstances but were tested when the 9/11 attacks occurred.
Codes across the United States are also moving towards performance measures in addition to the time-tested prescriptions of the codes (Solomon and Hagglund, 2001, p. 619). In New York City, for example, Mayor Bloomberg called for a review of the existing codes that had been in force since 1968 to conform to contemporary needs. New York has four construction codes namely the Building Code, Fuel Gas, Mechanical and Plumbing Codes (New New York City Construction Codes, n. d. , p. 1). The City government was caught flatfooted with an outdated construction code when the 9/11 attacks struck.
The amendments to the code include the adoption of the International Building Code (IBC) format, placing safety as a priority and preserving some elements of the existing codes while enhancing the “requirements for fire protection, construction safety, and structural integrity requirements for new buildings. ” (New New York City Construction Codes, n. d. , p. 1) Moore (n. d. ) defined building codes as “extratechnological laws that govern the design and construction of structures. ” (p. 262). The codes follow the dictates social and ethical mores where the protection of life and property is a priority.
It also traces its roots in the Hammurabi code where a builder was held responsible for a collapsed house that killed its occupants and applying the lex talionis principle of justice (p. 262). Codes also had grown out of the necessity to adhere to insurance regulations. Protection goals include all the contents of a building or warehouse that were insured. Failure to mitigate the risk like loss to fire would mean economic repercussions for the community or state (Solomon and Hagglund, 2001, p. 625).
Code prescriptions until the 1940’s prescribed a fire resistive building as steel framed or buildings that had “skeletal framework of steel columns and beams which supported the actual weight of the structure and its contents. ” (Portolan, n. d. ) The structural elements were fireproofed or encased in concrete or tile (Portolan, n. d. ) In the 1920’s, the codes also regulated the heights of buildings where height limitations had a direct relationship to the construction methods employed (Solomon and Hagglund, 2001, p. 626).
Each state though had its interpretation and regulations concerning construction practices. The National Fire Protection Association (NFPA) proposed a performance based approach to tall building designs with the hope the building designs and construction methodologies respond to the need for safer buildings. The NFPA outlined six goals to performance based building design. They include: Life Safety of Building Occupants; Property/Contents Protection; Mission Continuity; Environmental Consequence of Fire; Heritage/Cultural Preservation; and Fire Suppression Personnel Safety (Solomon and Hagglund, 2001, p.
632). However, not all directives and codes today follow the suggestions of NFPA. The National Fire Protection Association (NFPA) developed their standards specifically aimed at protecting both firefighters and civilians from fire-related injuries. Some of the standards relevant to the construction industry include NFPA 5000 (Building Construction and Safety Code); “NFPA 13 (Standard for the Installation of Sprinkler Systems); NFPA 501 (Standard on Manufactured Housing) (NIOSH, 2005, p. 3).
According to NIOSH (2005)”, while there are existing standard tests like ANSI (American National Standards Institute) or ASTM (American Society for Testing and Materials) that govern the safety measures in building materials and construction methodologies, these do not take into consideration real situations involving actual conflagrations and how fires would impact on the structural integrity of the structures (p. 4). NIOSH (2005) also pointed out that existing building codes enforced in various states were not designed specifically to protect firefighters.
The design focus was on evacuation procedures and how occupants in the building could escape to safety once an unfortunate event occurred (p.4). With the new reality that unfolded post-9/11, existing building codes must be reviewed for and in consideration of the risks involved when disasters strike. Basic Knowledge on Structural Behaviors of Buildings According to Portolan (n. d. (b)), there are five elements of a building that the firefighters need to consider when evaluating how buildings will behave in case of fire and which strategies to use to contain the problem.
They include: the type of construction, size of the building, age of the construction, renovation and occupancy. These are essential information that firefighters can use to plan their course of actions. In addition, knowledge on the behavior of the different structural elements of the building is also imperative. Structural loading creates different stresses on the structures and they may occur separately or in combination. The stresses include compression, tensile and shear stresses (Portolan, n. d (b). ). Compression acts when materials are pressed against each other.
Tensile stresses happen when the structural elements are pulled in two different directions. Shear stresses cause materials to fracture and slide across the defect in the opposite direction (Portolan, n. d (b). ). Structural elements of the building are subjected to different loads. Columns are commonly subjected to axial loads. Eccentric loads are directed along a parallel axis to the longitudinal section of the structural member and are off-centered. Torsion loads can cause twisting in the structural elements (Portolan, n. d (b).
) Aside from the stresses, the firefighters also need to consider which part of the structures are vulnerable or the structural integrity had been compromised because of the fire. When steel beams are subjected to unusually high temperature, the structural member may expand and elongate. If both ends are tightly secured, torsion stresses may cause twisting in beams (Portolan, n. d. (b)). Columns carry the greatest axial loads. The more slender the column, the more it is susceptible to buckling. When axial loads shift to eccentric or torsion loads, it could also be a cause of failure (Portolan, n. d. (b)).
About 60% of the buildings in the United States use the truss system for roofs (NIOSH, 2005, p. 1). Most of the truss systems were made of wood materials. Recent innovation introduced lighter construction materials for truss systems including steel and lighter weight materials intended to accommodate wider spans. Under normal conditions, these engineered materials may perform well. However, when fire occurs, they may be weakened and compromised causing the collapse of roof and floor systems (p. 1). Types of Building Collapses Due to Fire Collapse patterns are different for each element of the building.
Walls often collapse in a 90-degree angle. These walls are often constructed using reinforced masonry. Curtain wall collapse occurs when the outer veneer becomes disconnected and they fall straight down to the base of the wall. This type of collapse is also exhibited by unreinforced walls. Inward or outward collapse may also occur if the wall is breached or at areas where it is considerably weaker like door or window openings (Portolan, n. d. (b)). Truss systems of roof and floor often cave-in as their structural integrities were affected by conflagration. Steel trusses are also susceptible to expansion and torsion stresses.
Often, firefighters used visual indicators to predict an impending collapse. But these were not enough to prevent accidents from happening. NIOSH (2005) listed three conditions where truss collapse occurs. First, when a firefighter works on the roof top of the burning building, chances of a cave-in is extremely high because the hidden structural members of the truss system had already been subjected to extreme temperatures thereby weakening them. Second, firefighters working inside the burning structure are also subjected to the risk of the entire roof falling onto them.
Finally, failed truss systems can precipitate other parts of the structure to collapse like walls (p. 4). Another type of collapse usually found in tall structures is referred to as progressive collapse. Nair (2004) defined progressive collapse as “collapse of all or a large part of a structure precipitated by failure or damage of a relatively small part of it. ” (p. 1) This theory was used in part to explain why the twin towers of the World Trade Center in New York collapsed. Conclusion Knowing how structural members behave during fire would mitigate the risk factors and prevent injuries and deaths.
Part of the training of firefighters is knowing how to evaluate the condition of the burning edifice before going in and making a plan of action. The different studies on the behavior of buildings on fire proved to be valuable to firefighters. The recent events had also made regulating bodies review their out-dated Codes. Existing building codes do not include the protection of firefighters in the event of fire. The NFPA and the IBC remedied that deficiency. However, code changes were also met with opposition. Building codes were primarily implemented with economic considerations in mind.
It would prove to be more costly for the building owner if NFPA or IBC was followed. According to Gips (2005), of the various proposals for change in the Codes, only one was acceptable and included in the IBC. It concerned the fire-resistance ratings of buildings of 420 feet or higher. The new code required a “minimum three-hour structural fire-resistance rating, whether sprinklers are present or not. ” (p. 42+). Other provisions that would make it safer for both firefighters and occupants need more work. References Dunn, V. (2007). Dunn’s Dispatch: 9 firefighters die fighting fire in South Carolina furniture storeroom fire.
Retrieved 26 June 2007 from: http://cms. firehouse. com/content/article/article. jsp? sectionId=14&id=55205 FEMA’s US Fire Administration (2002). USA releases preliminary firefighter fatality statistics for 2001. Retrieved 26 June 2007 from: http://mcftoa. org/Deathstats1. htm Gips, M. A. (2005, March). The Challenge of Making Safer Structures: Three and a Half Years after 9-11, Building Codes Are Just Starting to Reflect Lessons Learned from the World Trade Center Collapse. Security Management, 49, 42+. Retrieved June 27, 2007, from Questia database: http://www. questia. com/PM. qst? a=o&d=5008988697 Moore, S. A. (n. d.
) Building Codes in Encyclopedia of Science, Technology and Ethics, 262-266 Retrieved 26 June 2007 from: http://soa. utexas. edu/faculty/moore/selectpub/enc_buildingcodes. pdf Nair, R. S. (2004) Progressive collapse basics. Retrieved 27 June 2007 from: http://www. aisc. org/Content/ContentGroups/Documents/Selected_Nair/nairhotlink2. pdf New New York City Construction Codes (n. d. ) Retrieved 26 June 2007 from: http://nyc. gov/html/dob/downloads/pdf/cons_code_faqs. pdf NIOSH (2005) Preventing injuries or deaths of firefighters due to truss system failures. Retrieved 27 June 2007 from: http://www. cdc. gov/niosh/docs/2005-132/pdfs/2005-132.
pdf Portolan, C. (n. d. ) Building Construction –Special situations Retrieved 27 June 2007 from: http://www. lbfdtraining. com/Pages/buildingconstruction/specialsituations. html Portolan, C. (n. d. (b)) Glossary of building construction terminology Retrieved 27 June 2007 from: http://www. lbfdtraining. com/Pages/buildingconstruction/bconstructintro. html Solomon, R. E. and Hagglund, B. (2001) Performance code requirements in the tall building environment in Tall buildings and urban habitat: Cities in the third millennium. Council On Tall Buildings And Urban Habitat – orgname. New York: Spon Press, 619-634.