Previous Posts in This Series …
2011-10-25: NIST’s Recommendations on the 9-11 WTC Building Collapses … GROUP 1. Increased Structural Integrity – Recommendations 1, 2 & 3 (out of 30)
2011-11-18: NIST WTC Recommendations 4-7 > Structural Fire Endurance … GROUP 2. Enhanced Fire Endurance of Structures – Recommendations 4, 5, 6 & 7
2011-11-24: NIST WTC Recommendations 8-11 > New Design of Structures … GROUP 3. New Methods for Fire Resisting Design of Structures – Recommendations 8, 9, 10 & 11
2011-11-25: NIST WTC Recommendations 12-15 > Improved Active Protection … GROUP 4. Improved Active Fire Protection – Recommendations 12, 13, 14 & 15
2011-11-30: NIST Recommendations 16-20 > Improved People Evacuation … GROUP 5. Improved Building Evacuation – Recommendations 16, 17, 18, 19 & 20
2011-12-04: NIST WTC Recommendations 21-24 > Improved Firefighting … GROUP 6. Improved Emergency Response – Recommendations 21, 22, 23 & 24
2011-12-07: SOME PRELIMINARY COMMENTS …
1. Concerning Recommendation 25 below … yes, this Recommendation applies to the types of organizations identified in the text, but it should also be understood as applying to ALL Organizations … public or private, governmental or non-governmental or quasi-governmental, whatever, etc … ‘supported’ (see the text further down in Recommendation 25) with rigorous enforcement, in all cases, by publically appointed building control officials and/or by private, independent, competent technical control professionals.
Once more … and again and again (!) … confirmed by the sort of debacle seen at the Priory Hall Apartment Complex, in Dublin … Self-Certification / Self-Approval, i.e. ‘lite’ regulation, does not work. For National Authorities Having Jurisdiction (AHJ’s), however, it is a cheap solution to a difficult, resource-devouring issue, i.e. protecting society and the consumer … in that order.
2. Concerning the Footnote to Recommendation 26 below … the choice should never be between either Fire Compartmentation or Sprinklers … or the other way around, whichever you prefer. Neither is 100% reliable !
The division of a building into fire-tight compartments, by fire and smoke resisting elements of construction, in order …
- to contain an outbreak of fire, and to facilitate effective firefighting ;
- to prevent damage, within the building, to other adjoining compartments and/or spaces ;
- to protect a compartment interior from external fire attack, e.g. fire spread across the building’s facade or from an adjacent building ;
- to minimize adverse, or harmful, environmental impacts outside the building.
As developed as that definition is above, Fire Compartmentation should be regarded as just one Fire Safety Strategy / Fire Engineering Strategy … not the only strategy, and certainly not the main strategy.
Here are two reasons why not …
a) The connection between compartment size and the ability to effectively fight a fire within a space of limited volume has been lost … so more and more, commercial pressure is being exerted on national authorities to expand the acceptable compartment sizes in buildings … which significantly increases the fire hazard ;
[ Remembering the difference between the limited Fire Safety Objectives of Building Codes/Regulations and the much broader Project-Specific Fire Engineering Objectives of Ethical Fire Engineering required to protect society and the full interests of our clients … it is easy to understand why national authorities feel that they can respond positively to such commercial pressures.]
b) In a Sustainable Building … it is a very common design strategy to take advantage of the natural patterns of air movement in a building, for either cooling or heating purposes, depending on local climate conditions. So there is simply no compartmentation, as understood in conventional fire engineering terms … and this throws up a fundamental conflict between the two. To be discussed in another post !
3. Concerning the 2nd Footnote to Recommendation 28 below … in the very same New York City … at 09.40 hrs on a Saturday morning, 28 July 1945 … lost in fog, a B-25 Bomber slammed head-on into the 79th Floor of the Empire State Building … and caused enormous damage. That building is still standing today … and surprise, surprise … there was aviation fuel in the B-25 !
In a similar vein … Fire-Induced Progressive Collapse was not observed for the first time, in New York, on 11 September 2001 !
2005 NIST WTC RECOMMENDATIONS
GROUP 7. Improved Procedures and Practices
The procedures and practices used in the design, construction, maintenance, and operation of buildings should be improved to include encouraging code compliance by non-governmental and quasi-governmental entities, adoption and application of egress and sprinkler requirements in codes for existing buildings, and retention and availability of building documents over the life of a building.
NIST WTC Recommendation 25.
Non-governmental and quasi-governmental entities that own or lease buildings and are not subject to building and fire safety code requirements of any governmental jurisdiction are nevertheless concerned about the safety of building occupants and responding emergency personnel. NIST recommends that such entities be encouraged to provide a level of safety that equals or exceeds the level of safety that would be provided by strict compliance with the code requirements of an appropriate governmental jurisdiction. NIST further recommends that as-designed and as-built safety be certified by a qualified third party, independent of the building owner(s). The process should not use self-approval for code enforcement in areas including interpretation of code provisions, design approval, product acceptance, certification of the final construction, and post-occupancy inspections over the life of the buildings.*
[ * F-46 The long-standing stated policy of the Port Authority of New York & New Jersey (PANYNJ) was to meet and, where appropriate, exceed the requirements of local building and fire codes, and it entered into agreements with the New York City Department of Buildings and the Fire Department of the City of New York in accordance with that policy. Although the PANYNJ sought review and concurrence from New York City in the areas listed in the Recommendation, the PANYNJ was not required to yield, and appears not to have yielded, approval authority to New York City. The PANYNJ was created as an interstate entity, a ‘body corporate and politic’, under its charter, pursuant to Article 1, Section 10 of the United States Constitution permitting compacts between states. Further, there are many other similar non-governmental and quasi-governmental entities in the U.S. A comprehensive review of documents conducted as part of this Investigation suggests that the WTC towers generally were designed and maintained consistent with the requirements of the 1968 New York City Building Code. Areas of concern included fireproofing of the WTC floor system, height of tenant separation walls, and egress requirements for the assembly use spaces of ‘Windows of the World’ in WTC Tower 1 and the ‘Top of the World’ Observation Deck in WTC Tower 2. These areas of concern did not play a significant role in determining the outcomes related to the events on 11th September 2001.]
NIST WTC Recommendation 26.
NIST recommends that state and local jurisdictions adopt and aggressively enforce available provisions in building codes to ensure that egress and sprinkler requirements are met by existing buildings.* Further, occupancy requirements should be modified where needed (such as when there are assembly use spaces within an office building) to meet the requirements in model building codes. Provisions related to egress and sprinkler requirements in existing buildings are available in such codes as the International Existing Building Code (IEBC), International Fire Code, NFPA 1, NFPA 101, and ASME A 17.3. For example, the IEBC defines three levels of building alteration (removal and replacement or covering of existing materials and equipment, reconfiguration of space or system or installation of new equipment, and extending the work area in excess of 50% of the aggregate area of the building). At the lowest level, there are no upgrade implications for sprinklers and the egress system. At the next level, sprinklers are required in work areas serving greater than 30 people if certain other conditions related to building height and use such as shared exits also are met. There are numerous requirements for means of egress, including number of exits, specification of doorsets, dead-end corridors and travel distances, lighting, signage, and handrails. At the highest level, the sprinkler and egress requirements are identical to the second level without the minimum 30-person restriction and the other conditions related to building height and use. The Life Safety Code (NFPA 101) applies retroactively to all buildings, independent of whether any work is currently being done on the building, and ASME A 17.3 applies retroactively to all elevators as a minimum set of requirements.
[ * F-47 The WTC towers were unsprinklered when built. It took nearly 28 years after passage of New York City Local Law 5 in 1973, which required either compartmentation or sprinklering, for the buildings to be fully sprinklered (the Port Authority chose not to use the compartmentation option in Local Law 5). This was about 13 years more than the 15-year period for full compliance with Local Law 5 that was set by Local Law 84 of 1979.]
NIST WTC Recommendation 27.
NIST recommends that building codes incorporate a provision that requires building owners to retain documents, including supporting calculations and test data, related to building design, construction, maintenance, and modifications over the entire life of the building.* Means should be developed for off-site storage and maintenance of the documents. In addition, NIST recommends that relevant information be made available in suitably designed hard copy or electronic formats for use by emergency responders. Such information should be easily accessible by responders during emergencies. Model Building Codes: Model building codes should incorporate this Recommendation. State and local jurisdictions should adopt and enforce these requirements.
[ * F-48 The availability of inexpensive electronic storage media and tools for creating large searchable databases makes this feasible.]
NIST WTC Recommendation 28.
NIST recommends that the role of the ‘Design Professional in Responsible Charge’* be clarified to ensure that: (1) all appropriate design professionals (including, e.g. the fire protection engineer) are part of the design team providing the highest standard of care when designing buildings employing innovative or unusual fire safety systems;** and (2) all appropriate design professionals (including, e.g. the structural engineer and the fire protection engineer) are part of the design team providing the highest standard of care when designing the structure to resist fires, in buildings that employ innovative or unusual structural and fire safety systems. Affected Standards: AIA Practice Guidelines. Model Building Codes: The International Building Code (IBC), which already defines ‘Design Professional in Responsible Charge’, should be clarified to address this Recommendation. NFPA 5000 should incorporate the ‘Design Professional in Responsible Charge’ concept, and address this Recommendation.
[ * F-49 In projects involving a design team, the ‘Design Professional in Responsible Charge’ – usually the lead architect – ensures that the team members use consistent design data and assumptions, co-ordinates overlapping specifications, and serves as the liaison between the enforcement and reviewing officials and the owner. This term is defined in the International Building Code (IBC) and in the International Code Council’s Performance Code for Buildings and Facilities (where it is the Principal Design Professional).]
[ ** F-50 If the fire safety concepts in tall buildings had been sufficiently mature in the 1960’s, it is possible that the risks associated with jet-fuel ignited multi-floor fires might have been recognized and taken into account when the impact of a Boeing 707 aircraft was considered by the structural engineer during the design of the WTC towers.]