Disproportionate Damage

Progressive Collapse of WTC 7 – 2008 NIST Recommendations – Part 1 of 2

Posted by CJ Walsh

See the 1st Series of Posts on the 2005 NIST WTC 1 & 2 Collapse Recommendations … which began, here, towards the end of 2011 …

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)

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Colour plan showing the World Trade Center Complex in New York City, and its surrounding neighbourhood in Manhattan. By means of yellow shading and annotation in red text, the extent of direct damage caused by the collapse of the 2 WTC Towers on 11 September 2001 is shown. Not shown is the much greater extent of indirect damage caused, e.g. dust and debris from the collapses clogged up and destroyed air conditioning systems and ductwork in buildings. Everywhere south of Canal Street was a disaster zone. Also not shown is the damage caused by WTC 7, at the north-eastern tip of the Complex, which collapsed late on the afternoon of 9-11. Click to enlarge.
Colour plan showing the World Trade Center Complex in New York City, and its surrounding neighbourhood in Manhattan. By means of yellow shading and annotation in red text, the extent of direct damage caused by the collapse of the 2 WTC Towers on 11 September 2001 is shown. Not shown is the much greater extent of indirect damage caused, e.g. dust and debris from the collapses clogged up and destroyed air conditioning systems and ductwork in buildings. Everywhere south of Canal Street was a disaster zone. Also not shown is the damage caused by WTC 7, at the north-eastern tip of the Complex, which collapsed late on the afternoon of 9-11. Click to enlarge.

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2012-01-18:  SOME PRELIMINARY COMMENTS …

  1.     World Trade Center Building 7 was a 47 Storey Office Building located at the north -eastern tip of the WTC Complex in Lower Manhattan, New York City.  It had been built on top of an existing Consolidated Edison of New York electric power substation, on land owned by the Port Authority of New York and New Jersey.

On Tuesday, 11 September 2001 … WTC Building 7 was on fire for almost seven hours … from the time of the collapse of WTC Tower 1 – North Tower, just before 10.30 hrs (local time), until 17.21 hrs … when WTC 7 failed completely, collapsing progressively as a result of ‘real’ fires – as distinct from ‘standard test’ fires – on many floors. 

There were only two certainties on that fateful day (9-11) … the Fire-Induced Progressive Collapse of WTC Building 7 could no longer be ignored by the International Fire Science and Engineering Community … and the ‘reality’, which Modern Fire Engineering must now confront, was significantly altered.  Secondly, it is NEVER acceptable to a general population for buildings to collapse !

Later in 2008, the Mumbai ‘Hive’ Attacks would add a sinister new ingredient to the standard threat profile for buildings, their occupants, and emergency services.

However, long before 9-11 and Mumbai, the growing complexity of modern communities and their rapidly evolving architectural forms had left the Fire Engineer far behind, unable to respond to the new fire safety challenges posed.

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  2.     The second of the NIST Publications being referenced in this New Series of Posts is as follows …

NIST (National Institute of Standards and Technology).  August 2008.  Federal Building and Fire Safety Investigation of the World Trade Center Disaster: Final Report on the Collapse of World Trade Center Building 7.  NIST NCSTAR 1A.  Gaithersburg, MD, USA.

This 2008 NIST Report contains, in Chapter 5, a list of 13 Recommendations for Action (A-M), grouped together under the same 8 Subject Headings used in the 2005 NIST Report (NCSTAR 1) …

     i)       Increased structural integrity … Recommendation A ;

     ii)      Enhanced fire endurance of structures … Recommendations B, C, D & E ;

     iii)     New methods for fire resisting design of structures … Recommendations F & G ;

     iv)     Improved active fire protection … Recommendation H ;

     v)      Improved building evacuation … Long before its collapse, all occupants/users had evacuated WTC 7 … No Recommendation ;

     vi)     Improved emergency response … Recommendation I ;

     vii)    Improved procedures and practices … Recommendations J & K ;   and

     viii)   Education and training … Recommendations L & M.

NIST has clearly stated that “the urgency of these Recommendations is substantially reinforced by their pertinence to the collapse of a tall building that was based on a structural system design that is in widespread use”.

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  3.     The Colour Coding of Texts which I am using in this new series of posts … where NIST has presented new texts relating to WTC Building 7, these are shown in blue … where NIST has chosen to reinforce earlier texts from the 2005 Report on the WTC Towers 1 & 2 Collapses, these are shown in black.  The important new paragraphs describing the critical relevance of WTC Building 7 are shown in red.

Please pay particular attention to these Red Paragraphs.  Having carefully digested their contents … then if, by any chance, you happen to encounter somebody who still insists that the NIST 9-11 WTC Recommendations have no relevance to the design, construction, management and operation of ALL Buildings … that person is either living in Alice’s Wonderland … or he/she has never bothered to read the NIST Recommendations in the first place !!

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  4.     While it is still essential to distinguish clearly between the two closely related structural concepts below … I would like to take this opportunity to bring to your attention a necessary and important modification … more, a refinement … to the definition of Fire-Induced Progressive Collapse …

Disproportionate Damage

The failure of a building’s structural system  (i) remote from the scene of an isolated overloading action;  and (ii) to an extent which is not in reasonable proportion to that action.

Fire-Induced Progressive Collapse

The sequential growth and intensification of structural distortion and displacement, beyond fire engineering design parameters, and the eventual failure of elements of construction in a building – during a fire and the ‘cooling phase’ afterwards – which, if unchecked, will result in disproportionate damage, and may lead to total building collapse.

This modification/refinement recognizes the following … that Fire-Induced Progressive Collapse may commence long before any breach occurs in a Fire Compartment Boundary … that, as a result of rampant commercial pressures in our societies, the tendency is for Compartment Volumes to become far too large to be any longer effective … and in the case of a Sustainable Building, for example, where natural patterns of air movement in buildings are used for either heating or cooling purposes, there may be no Compartments at all !

Restricting the application of one or both of these structural concepts, in law, to Multi-Storey Buildings, i.e. in many jurisdictions, those buildings having 5 or more storeys … is a purely arbitrary cut-off point.

CIB W14’s Research Working Group IV: ‘Structural Reliability & Fire-Induced Progressive Collapse’ would argue, rationally, that both of these concepts are fundamental to all structural fire engineering design.

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  5.     Structural Fire Engineering is concerned with those aspects of fire engineering which relate to structural design for fire, and the complex architectural interaction between a building’s structure and fabric, i.e. non-structure, under conditions of fire and its immediate aftermath.

As Chair of CIB W14’s Research Working Group IV … I will shortly be making a Workshop Presentation in Europe, the aim of which will be to set the scene for the launch of an International CIB W14 Research WG IV Reflection Document;  the specific objective of the Presentation, however, will be to accurately describe the phenomenon that is Fire-Induced Progressive Collapse … and to outline a necessary new design approach which will fulfil future requirements, legal and otherwise, concerning adequate resistance to this phenomenon.

It will be shown that the new design approach is fully compatible with the Recommendations contained in the 2005 and 2008 NIST Reports on the 9-11 World Trade Center Buildings 1, 2 & 7 Collapses – NCSTAR 1 & NCSTAR 1A.

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2008 NIST WTC 7 RECOMMENDATIONS  (Final Report NCSTAR 1A)

5.1  GENERAL

In its final report on the collapse of the World Trade Center Towers (NIST NCSTAR 1), NIST made 30 Recommendations for improving the safety of buildings, occupants, and emergency responders.  These encompass increased structural integrity, enhanced fire endurance of structures, new methods for fire resisting design of structures, improved active fire protection, improved building evacuation, improved emergency response, improved procedures and practices, and education and training.

WTC 7 was unlike the WTC Towers in many respects.  It was a more typical tall building in the design of its structural system.  It was not struck by an airplane.  The fires in WTC 7 were quite different from those in the Towers.  Since WTC 7 was not doused with thousands of litres of jet fuel, large areas of any floor were not ignited simultaneously.  Instead, the fires in WTC 7 were similar to those that have occurred previously in several tall buildings where the sprinklers did not function or were not present.  These other buildings did not succumb to their fires and collapse, because they were of structural designs that differed from that of WTC 7.

The Investigation Team has compiled a list of key factors that enabled ordinary fires to result in an extraordinary outcome.  In so doing, the Team recognized that there were additional aspects to be included in the content of some of the earlier 30 Recommendations.

Based on the findings of this Investigation, NIST has identified 1 New Recommendation and has reiterated 12 Recommendations from the Investigation of the WTC Towers.

The urgency of the Prior Recommendations is substantially reinforced by their pertinence to the collapse of a tall building that is based on a structural system design that is in widespread use.  A few of the Prior Recommendations have been modified to reflect the findings of this Investigation.

The partial or total collapse of a building due to fires is an infrequent event.  This is particularly true for buildings with a reliably operating active fire protection system, such as an automatic fire sprinkler system.  A properly designed and operating automatic sprinkler system will contain fires while they are small and, in most instances, prevent them from growing and spreading to threaten structural integrity.

The intent of current practice, based on prescriptive standards and codes, is to achieve life safety, not collapse prevention.  However, the key premise of NIST’s Recommendations is that buildings should not collapse in infrequent (worst-case) fires that may occur when active fire protection systems are rendered ineffective, e.g. when sprinklers do not exist, are not functional, or are overwhelmed by the fire.

Fire scenarios for structural design based on single compartment or single floor fires are not appropriate representations of infrequent fire events.  Such events have occurred in several tall buildings resulting in unexpected substantial losses.  Instead, historical data suggests that infrequent fires which should be considered in structural design have characteristics that include:  ordinary combustibles and combustible load levels, local fire origin on any given floor, no widespread use of accelerants, consecutive fire spread from combustible to combustible, fire-induced window breakage providing ventilation for continued fire spread and accelerated fire growth, concurrent fires on multiple floors, and active fire protection systems rendered ineffective.  The fires in WTC 7 had all of these characteristics.

NIST believes the Recommendations are realistic, appropriate, and achievable within a reasonable period of time.  NIST strongly urges that immediate and serious consideration be given to these Recommendations by the building and fire safety communities in order to achieve appropriate improvements in the way buildings are designed, constructed, maintained, and used – with the goal of making buildings safer in future emergencies.

A complete listing of all 13 Recommendations (Recommendations A through L) based on this Investigation follows.  Under a few of the Recommendations, the pertinent lesson from the reconstruction of the WTC 7 Collapse is reflected in the form of a modification.   For the 12 Reiterated Recommendations, the pertinent codes, standards, and organizations were listed in Table 9-1, and Tables 9-2a through 9-2c of NIST NCSTAR 1 and are not repeated here.  For the 1 New Recommendation, B, this information is provided in the text.

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5.1.1     GROUP 1.  Increased Structural Integrity

The standards for estimating the load effects of potential hazards (e.g. progressive collapse, wind) and the design of structural systems to mitigate the effects of those hazards should be improved to enhance structural integrity.

NIST WTC 7 Recommendation A  (NCSTAR 1  Recommendation 1).

NIST recommends that:  (1) progressive collapse be prevented in buildings through the development and nationwide adoption of consensus standards and code provisions, along with the tools and guidelines needed for their use in practice;  and (2) a standard methodology be developed – supported by analytical design tools and practical design guidance – to reliably predict the potential for complex failures in structural systems subjected to multiple hazards.

Relevance to WTC 7:  Had WTC 7 been expressly designed for prevention of fire-induced progressive collapse, it would have been sufficiently robust to withstand local failure due to the fires without suffering total collapse.

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5.1.2     GROUP 2.  Enhanced Fire Endurance of Structures

The procedures and practices used to ensure the fire endurance of structures should be enhanced by improving the technical basis for construction classifications and fire resistance ratings, improving the technical basis for standard fire resistance testing methods, use of the ‘structural frame’ approach to fire resistance ratings, and developing in-service performance requirements and conformance criteria for sprayed fire resisting materials.

NIST WTC 7 Recommendation B  (New)

NIST recommends that buildings be explicitly evaluated to ensure the adequate performance of the structural system under worst-case design fires with any active fire protection system rendered ineffective.  Of particular concern are the effects of thermal expansion in buildings with one or more of the following features:  (1) long-span floor systems* which experience significant thermal expansion and sagging effects;  (2) connection designs (especially shear connections) that cannot accommodate thermal effects;  (3) floor framing that induces asymmetric thermally-induced (i.e. net lateral) forces on girders;  (4) shear studs that could fail due to differential thermal expansion in composite floor systems;  and (5) lack of shear studs on girders.  Careful consideration should also be given to the possibility of other design features that may adversely affect the performance of the structural system under fire conditions.

[ * F-6   Typical floor span lengths in tall office buildings are in the range of 12-15 metres;  this range is considered to represent long-span systems.  Thermal effects (e.g. thermal expansion) that may be significant in long-span buildings may also be present in buildings with shorter span lengths, depending on the design of the structural system.]

Building owners, operators, and designers are strongly urged to act upon this Recommendation.  Engineers should be able to design cost-effective fixes to address any areas of concern that are identified by these evaluations.  Several existing, emerging, or even anticipated capabilities could have helped prevent the collapse of WTC 7.  The degree to which these capabilities improve performance remains to be evaluated.  Possible options for developing cost-effective fixes include:

  • More robust connections and framing systems to better resist the effects of thermal expansion on the structural system ;
  • Structural systems expressly designed to prevent progressive collapse.  The current model building codes do not require that buildings be designed to resist progressive collapse ;
  • Better thermal insulation (i.e. reduced conductivity and/or increased thickness) to limit heating of structural steel and to minimize both thermal expansion and weakening effects.  Currently, insulation is used to protect steel strength, but it could also be used to maintain a lower temperature in the steel framing to limit thermal expansion ;
  • Improved compartmentation in tenant areas to limit spread of fires ;
  • Thermally resisting window assemblies which limit breakage, reduce air supply, and retard fire growth.

Industry should partner with the research community to fill critical gaps in knowledge about how structures perform in real fires, particularly considering:  the effects of fire on the entire structural system; the interactions between sub-systems, elements, and connections; and scaling of fire test results to full-scale structures, especially for structures with long-span floor systems.

Affected Standards:  ASCE 7, ASCE/SFPE 29, AISC Specifications, and ACI 318.  Development of performance objectives, design criteria, evaluation methods, design guidance, and computational tools should begin promptly, leading to new standards.

Model Building Codes:  The new standard should be adopted in model building codes (IBC, NFPA 5000) by mandatory reference to, or incorporation of, the latest edition of the standard.

Relevance to WTC 7:  The effects of restraint of free thermal expansion on the steel framing systems, especially for the long spans on the east side of WTC 7, were not considered in the structural design and led to the initiation of the building collapse.

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NIST WTC 7 Recommendation C  (NCSTAR 1  Recommendation 4).

NIST recommends evaluating, and where needed improving, the technical basis for determining appropriate construction classifications and fire rating requirements (especially for tall buildings) – and making related code changes now, as much as possible – by explicitly considering factors including:*

[ * F-7  The construction classification and fire rating requirements should be risk-consistent with respect to the design-basis hazards and the consequences of those hazards.  The fire rating requirements, which were originally developed based on experience with buildings less than 20 storeys in height, have generally decreased over the past 80 years since historical fire data for buildings suggest considerable conservatism in those requirements.  For tall buildings, the likely consequences of a given threat to an occupant on the upper floors are more severe than the consequences to an occupant on the first floor or the lower floors.  For example, with non-functioning elevators, both of the time requirements are much greater for full building evacuation from upper floors and emergency responder access to those floors.  The current height and areas tables in building codes do not provide the technical basis for the progressively increasing risk to an occupant on the upper floors of tall buildings that are much greater than 20 storeys in height.]

  • timely access by emergency responders and full evacuation of occupants, or the time required for burnout without partial collapse ;
  • the extent to which redundancy in active fire protection systems (sprinklers and standpipe, fire alarm, and smoke management) should be credited for occupant life safety ;*

[ * F-8  Occupant life safety, prevention of fire spread, and structural integrity are considered separate safety objectives.]

  • the need for redundancy in fire protection systems that are critical to structural integrity ;*

[ * F-9  The passive fire protection system (including the application of fire protection insulation, compartmentation, and fire stopping) and the active sprinkler system each provide redundancy for maintaining structural integrity in a building fire, should one of the systems fail to perform its intended function.]

  • the ability of the structure and local floor systems to withstand a maximum credible fire scenario* without collapse, recognizing that sprinklers could be compromised, not operational, or non-existent ;

[ * F-10  A maximum credible fire scenario includes conditions that are severe, but reasonable to anticipate, conditions related to building construction, occupancy, fire loads, ignition sources, compartment geometry, fire control methods, etc., as well as adverse, but reasonable to anticipate operating conditions.]

  • compartmentation requirements (e.g. 1,200 sq.m*) to protect the structure, including fire rated doorsets and automatic enclosures, and limiting air supply (e.g. thermally resisting window assemblies) to retard fire spread in buildings with large, open floor plans ;

[ * F-11  Or a more appropriate limit, which represents a reasonable area for active fire fighting operations.]

  • the effect of spaces containing unusually large fuel concentrations for the expected occupancy of the building ;   and
  • the extent to which fire control systems, including suppression by automatic or manual means, should be credited as part of the prevention of fire spread.

Relevance to WTC 7:  The floor systems in WTC 7 failed at lower temperatures because thermal effects within the structural system, especially thermal expansion, were not considered in setting the fire rating requirements in the construction classification, which are determined using the ASTM E 119 or equivalent testing standard.

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NIST WTC 7 Recommendation D  (NCSTAR 1  Recommendation 5).

NIST recommends that the technical basis for the century-old standard for fire resistance testing of components, assemblies and systems be improved through a national effort.  Necessary guidance also should be developed for extrapolating the results of tested assemblies to prototypical building systems.  A key step in fulfilling this Recommendation is to establish a capability for studying and testing components, assemblies, and systems under realistic fire and load conditions.

Of particular concern is that the Standard Fire Resistance Test does not adequately capture important thermally-induced interactions between structural sub-systems, elements, and connections that are critical to structural integrity.  System-level interactions, especially due to thermal expansion, are not considered in the standard test method since columns, girders, and floor sub-assemblies are tested separately.  Also, the performance of connections under both gravity and thermal effects is not considered.  The United States currently does not have the capability for studying and testing these important fire-induced phenomena critical to structural safety.

Relevance to WTC 7:  The floor systems failed in WTC 7 at shorter fire exposure times than the specified fire rating (two hours) and at lower temperatures because thermal effects within the structural system, especially thermal expansion, were not considered in setting the endpoint criteria when using the ASTM E 110 or equivalent testing standard.  The structural breakdowns that led to the initiating event, and the eventual collapse of WTC 7, occurred at temperatures that were hundreds of degrees below the criteria that determine structural fire resistance ratings.

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NIST WTC 7 Recommendation E  (NCSTAR 1  Recommendation 7).

NIST recommends the adoption and use of the ‘structural frame’ approach to fire resistance ratings.  This approach requires all members that comprise the primary structural frame (such as columns, girders, beams, trusses, and spandrels) be fire protected to the higher fire resistance rating required for the columns.  The definition of the primary structural frame should be expanded to include bracing members that are essential to the vertical stability of the primary structural frame under gravity loading (e.g. girders, diagonal bracing, composite floor systems that provide lateral bracing to the girders) whether or not the bracing members carry gravity loads.  Some of these bracing members may not have direct connections to the columns, but provide stability to those members directly connected to the columns.  This Recommendation modifies the definition of the primary structural frame adopted in the 2007 supplement to the International Building Code (IBC).  The IBC considers members of floor or roof construction that are not connected to the columns not to be part of the primary structural frame.  This Recommendation ensures consistency in the fire protection provided to all of the structural elements that contribute to overall structural stability.  State and local jurisdictions should adopt and enforce this requirement.

Relevance to WTC 7:  Thermally-induced breakdown of the floor system in WTC 7 was a determining step in causing failure initiation and progressive collapse.  Therefore, the floor system should be considered as an integral part of the primary structural frame.

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NIST WTC Recommendations 12-15 > Improved Active Protection

Posted by CJ Walsh

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

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2011-11-25:  SOME PRELIMINARY COMMENTS …

  1.     Reliability has always been an issue with Active Fire Protection Systems … but, it is neither acknowledged, nor fully understood, that … Reliability Is Equally An Issue With Passive Fire Protection Measures !

Furthermore, the following should always be taken into account when considering the Safety Factors to be applied in calculating the level of satisfactory fire safety and protection which is provided in a specific project … one of the design objectives in Ethical Fire Engineering.

For example, if Category C below is indicative of the design and construction quality on a particular building site … just think of the Priory Hall Apartment Development in Dublin (!) … the Safety Factors to be applied in the design should be high … and with regard to actual construction, it should be expected that the Reliability of both Active Fire Protection Systems and Passive Fire Protection Measures will be initially low … with Life Cycle Reliability being entirely non-existent.

Quality of Fire Engineering Design & Related Construction 

Category A

(a)   Design of the works is exercised by an independent, appropriately qualified and experienced architect/engineer/fire engineer, with design competence relating to fire safety and protection in buildings … and, most importantly, that he/she interacts directly with the Project Design Professional in Responsible Charge ;

(b)   Installation/fitting of related construction products/systems is exercised by appropriately qualified and experienced personnel, with construction competence relating to fire safety and protection in buildings ;

(c)   Supervision of the works is exercised by appropriately qualified and experienced personnel from the principal construction organization ;

(d)   Regular inspections, by appropriately qualified and experienced personnel familiar with the design, and independent of the construction organization(s), are carried out to verify that the works are being executed in accordance with the fire engineering design.

Category B

(a)   Design of the works is exercised by an independent, appropriately qualified and experienced architect/engineer/fire engineer ;

(b)   Installation/fitting of fire-related construction products/systems is exercised by appropriately qualified and experienced personnel ;

(c)   Supervision of the works is exercised by appropriately qualified and experienced personnel from the principal construction organization.

Category C

This level of design and construction execution is assumed when the requirements for Category A or Category B are not met.

  2.     With regard to Recommendations 12 & 13 below … in an earlier post in this series, and elsewhere, I have defined Disproportionate Damage … and differentiated that structural concept from the related concept of Fire-Induced Progressive Collapse.

A significant number of countries include a requirement on Resistance to Disproportionate Damage in their national building codes.  Often, it is only necessary to consider this requirement in the case of buildings having 5 Storeys, or more … a completely arbitrary height threshold.  I would consider that adequately tying together the horizontal and vertical structural elements of a building … any building … is a fundamental principle of good structural engineering !!

Putting it simply … for the purpose of showing compliance with this structural requirement … it is necessary to demonstrate that a building will remain structurally stable if a portion of the building’s structure is removed … always remembering that every building comprises both structure and fabric, i.e. non-structure.

In reality this may happen, and quite often does happen, when, for example, a large truck runs into the side of a building, which can happen anywhere … or there is a gas explosion in some part of the building, which happened in Dublin’s Raglan House back in 1987, and many times in other countries … or a plane hits a high-rise building, which happened to Milan’s iconic Pirelli Tower in 2002, and to New York’s Empire State Building way back in 1945 … etc., etc.  Raglan House collapsed … the Pirelli Tower and the Empire State Building did not.

[ The World Trade Center Towers were originally designed to absorb the impact of a large plane and to remain structurally stable afterwards … in ambient conditions.  However, what was not considered in the ambient structural design was ‘fire’, i.e. the fuel tanks were empty and no fire in the building would be initiated as a result of the mechanical damage caused by the plane impact … which, on 11 September 2001, proved to be a ridiculous basis for any structural design !   This is why 9-11 should be regarded, at its core, as being a very serious ‘real’ fire incident.]

What I am leading up to is this … the concept of removing a portion of a building, and it remaining structurally stable afterwards … should now – logically and rationally – also be incorporated into the fire engineering design of Active Fire Protection Systems.  In other words, if a portion of a building is removed, will any particular Active Fire Protection System continue to operate effectively in the rest of the building ?   This has implications for the location and adequate protection of critical system components in a building … and for the necessary redundancy, zoning and back-up alternative routeing which must be designed into the system from the beginning !

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2005 NIST WTC RECOMMENDATIONS

GROUP 4.  Improved Active Fire Protection

Active fire protection systems (i.e. sprinklers, standpipes/hoses, fire alarms, and smoke management systems) should be enhanced through improvements to the design, performance, reliability, and redundancy of such systems.

NIST WTC Recommendation 12.

NIST recommends that the performance and possibly the redundancy of active fire protection systems (sprinklers, standpipes/hoses, fire alarms, and smoke management systems) in buildings be enhanced to accommodate the greater risks associated with increasing building height and population, increased use of open spaces, high-risk building activities, fire department response limits, transient fuel loads, and higher threat profile.  The performance attributes should deal realistically with the system design basis, reliability of automatic/manual operations, redundancy, and reduction of vulnerabilities due to single point failures.  Affected Standards:  NFPA 13, NFPA 14, NFPA 20, NFPA 72, NFPA 90A, NFPA 92A, NFPA 92B, and NFPA 101.  Model Building Codes:  The performance standards should be adopted in model building codes by mandatory reference to, or incorporation of, the latest edition of the standard.

NIST WTC Recommendation 13.

NIST recommends that fire alarm and communications systems in buildings be developed to provide continuous, reliable, and accurate information on the status of life safety conditions at a level of detail sufficient to manage the evacuation process in building fire emergencies;  all communication and control paths in buildings need to be designed and installed to have the same resistance to failure and increased survivability above that specified in present standards.  This should include means to maintain communications with evacuating occupants that can both reassure them and redirect them if conditions change.  Pre-installed fire warden telephone systems can serve a useful purpose and may be installed in buildings and, if so, they should be made available for use by emergency responders.  All communication and control paths in buildings need to be designed and installed to have the same resistance to failure and increased survivability above that specified in present standards.  Affected Standards:  NFPA 1, NFPA 72, and NFPA 101.  Model Building and Fire Codes:  The performance standards should be adopted in model building and fire codes by mandatory reference to, or incorporation of, the latest edition of the standard.

NIST WTC Recommendation 14.

NIST recommends that control panels at fire/emergency command stations in buildings be adapted to accept and interpret a larger quantity of more reliable information from the active fire protection systems that provide tactical decision aids to fire ground commanders, including water flow rates from pressure and flow measurement devices, and that standards for their performance be developed.  Affected Standards:  NFPA 1, NFPA 72, and NFPA 101.  Model Building and Fire Codes:  The performance standards should be adopted in model building and fire codes by mandatory reference to, or incorporation of, the latest edition of the standard.

NIST WTC Recommendation 15.

NIST recommends that systems be developed and implemented for:  (1) real time off-site secure transmission of valuable information from fire alarm and other monitored building systems for use by emergency responders, at any location, to enhance situational awareness and response decisions, and maintain safe and efficient operation;*  and (2) preservation of that information either off-site, or in a black box that will survive a fire or other building failure, for purposes of subsequent investigations and analysis.  Standards for the performance of such systems should be developed, and their use should be required.  Affected Standards:  NFPA 1, NFPA 72, and NFPA 101.  Model Building and Fire Codes:  The performance standards should be adopted in model building and fire codes by mandatory reference to, or incorporation of, the latest edition of the standard.

[ * F-35  The alarm systems in the WTC towers were only capable of determining and displaying: (a) areas that had at some time reached alarm point conditions; and (b) areas that had not.  The quality and reliability of information available to emergency responders at the Fire Command Station was not sufficient to understand the fire conditions.  The only information transmitted outside the buildings was the fact that the buildings had gone into alarm.  Further, the fire alarm system in WTC Building 7, which was transmitted to a monitoring service, was on ‘test mode’ during the morning of 11 September 2001, because routine maintenance was being performed.  Under test mode conditions: (1) the system is typically disabled for the entire building, not just for the area where work is being performed; and (2) alarm signals typically do not show up on an operator console.]

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NIST WTC Recommendations 8-11 > New Design of Structures

Posted by CJ Walsh

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

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2011-11-24:  SOME PRELIMINARY COMMENTS …

  1.     The first of two NIST Publications being referenced in this Series of Posts is as follows …

NIST (National Institute of Standards and Technology).  September 2005.  Federal Building and Fire Safety Investigation of the World Trade Center Disaster: Final Report on the Collapse of the World Trade Center Towers.  NIST NCSTAR 1.  Gaithersburg, MD, USA.

The 2005 NIST Report concludes, in Chapter 9, with a list of 30 Recommendations for Action, grouped together under the following 8 Subject Headings …

i)        Increased structural integrity ;

ii)       Enhanced fire endurance of structures ;

iii)      New methods for fire resisting design of structures ;

iv)      Enhanced active fire protection ;

v)       Improved building evacuation ;

vi)      Improved emergency response ;

vii)     Improved procedures and practices ;   and

viii)    Education and training.

NIST has clearly stated that “the numerical ordering (of the Recommendations) does not reflect any priority”.

From my point of view, the 2005 NIST Report is especially noteworthy for the emphasis placed on:

(a)     The 3 R’s … Reality – Reliability – Redundancy ;

(b)     Evacuation Way Finding … should be ‘intuitive and obvious’ … a major challenge for building designers, since buildings are still typically designed for ‘access’ only.  In order to find the evacuation routes in a building, it is usually necessary to have a compass, a map, a magnifying glass, a torch … and a prayer book !!!   More about this in later posts …

  2.     However, following on from NIST’s emphasis on Reality … and just between you, me and the World Wide Web … there is a lot of misunderstanding in the International Fire Science and Engineering Community about what exactly is the Realistic End Condition.  But, here it goes …

Realistic End Condition:  A ‘real’ fire in a ‘real’ building, which is used by ‘real’ people with varying abilities in relation to self-protection, independent evacuation to a ‘place of safety’, and participation in the Fire Defence Plan for the building.

It is strange, therefore … and quite unacceptable … to have to point out that the Realistic End Condition IS NOT … a test fire or an experimental fire in a laboratory … or a design fire in a computer model, even IF it is properly validated !

  3.     With regard to Recommendation 8 below … NIST’s contention that “Current methods for determining the fire resistance of structural assemblies do not explicitly specify a performance objective” is not strictly the case.

If we examine Technical Guidance Document B (Ireland) and Approved Document B (England & Wales) once again, as examples close to home … Part B: ‘Fire Safety’ in both jurisdictions should be read in conjunction with its associated Part A: ‘Structure’, which contains a requirement on Disproportionate Damage.

In everyday practice, however, this never happens.  Instead, people dealing with Part B in both jurisdictions enter a sort of bubble … a twilight zone … and, if there is anything to do with structural performance in fire, they immediately refer to the Appendices at the back of both Guidance Documents (ignoring Part A altogether) … where we find a ‘single element’ approach to design, no consideration of connections, etc., etc., etc.

And … this fundamental error is further reinforced in Ireland because, under the national system of Fire Safety Certification for buildings, it is only Part B which is relevant.

At European Level, I would make the same point … under EU Regulation 305/2011 on Construction Products … Basic Requirement for Construction Works 2: ‘Safety in Case of Fire’ must be read in conjunction with Basic Requirement 1: ‘Mechanical Resistance & Stability’ … where we will again find a direct reference to Disproportionate Damage … and an indirect, but explicit, reference to Serviceability Limit States under normal conditions of use … including fire !

A major gap … the missing link at international level … is the failure, still, to elaborate and flesh out the structural concept of Fire-Induced Progressive Collapse.  More about this in later posts …

  4.     With regard to Recommendation 10 below … and amplifying my earlier comments concerning Recommendation 6 … the manufacturers of all Lightweight Structural Fire Protection Systems … not just the Sprayed Systems … have a lot to answer for.

Major question marks concerning Life Cycle Durability, and Resistance to Mechanical Damage at any stage in a building’s life cycle, hang over all of these systems.

Fire testing, alone, does not show that a Lightweight Structural Fire Protection System is ‘fit for its intended use’ !   And manufacturers well know this !!!

And as for the Installation of Lightweight Structural Fire Protection Systems on site … it’s a hornets’ nest that nobody wants to touch !

Vested interests … vested interests … vested interests !!!

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2005 NIST WTC RECOMMENDATIONS

GROUP 3.  New Methods for Fire Resisting Design of Structures

The procedures and practices used in the fire resisting design of structures should be enhanced by requiring an objective that uncontrolled fires result in burnout without partial or global (total) collapse.  Performance-based methods are an alternative to prescriptive design methods.  This effort should include the development and evaluation of new fire resisting coating materials and technologies, and evaluation of the fire performance of conventional and high-performance structural materials.

NIST WTC Recommendation 8.

NIST recommends that the fire resistance of structures be enhanced by requiring a performance objective that uncontrolled building fires result in burnout without partial or global (total) collapse.  Such a provision should recognize that sprinklers could be compromised, non-operational, or non-existent.  Current methods for determining the fire resistance of structural assemblies do not explicitly specify a performance objective.  The rating resulting from current test methods indicates that the assembly (component or sub-system) continued to support its superimposed load (simulating a maximum load condition) during the test exposure without collapse.  Model Building Codes:  This Recommendation should be included in the national model building codes as an objective, and adopted as an integral pert of the fire resistance design for structures.  The issue of non-operational sprinklers could be addressed using the existing concept of Design Scenario 8 of NFPA 5000, where such compromise is assumed and the result is required to be acceptable to the Authority Having Jurisdiction (AHJ).  Affected Standards:  ASCE-7, AISC Specifications, ACI 318, and ASCE/SFPE 29.

NIST WTC Recommendation 9.

NIST recommends the development of:  (1) performance-based standards and code provisions, as an alternative to current prescriptive design methods, to enable the design and retrofit of structures to resist real building fire conditions, including their ability to achieve the performance objective of burnout without structural or local fire collapse;  and (2) the tools, guidelines, and test methods necessary to evaluate the fire performance of the structure as a whole system.  Standards development organizations, including the American Institute of Steel Construction, have already begun developing performance-based provisions to consider the effects of fire in structural design.

This performance-based capability should include the development of, but not be limited to:

a.     Standard methodology, supported by performance criteria, analytical design tools, and practical design guidance;  related building standards and codes for fire resistance design and retrofit of structures, working through the consensus process for nationwide adoption;  comprehensive design rules and guidelines;  methodology for evaluating thermo-structural performance of structures;  and computational models and analysis procedures for use in routine design practice.

b.     Standard methodology for specifying multi-compartment, multi-floor fire scenarios for use in the design and analysis of structures to resist fires, accounting for building-specific conditions such as geometry, compartmentation, fuel load (e.g. building contents and any flammable fuels such as oil and gas), fire spread, and ventilation;  and methodology for rating the fire resistance of structural systems and barriers under realistic design-basis fire scenarios.

c.     Publicly available computational software to predict the effects of fires in buildings – developed, validated, and maintained through a national effort – for use in the design of fire protection systems and the analysis of building response to fires.  Improvements should include the fire behaviour and contribution of real combustibles;  the performance of openings, including door openings and window breakage, that controls the amount of oxygen available to support the growth and spread of fires and whether the fire is fuel-controlled or ventilation-controlled;  the floor-to-floor flame spread;  the temperature rise in both insulated and un-insulated structural members and fire barriers;  and the structural response of components, sub-systems, and the total building system due to the fire.

d.     Temperature-dependent thermal and mechanical property data for conventional and innovative construction materials.

e.     New test methods, together with associated conformance assessment criteria, to support the performance-based methods for fire resistance design and retrofit of structures.  The performance objective of burnout without collapse will require the development of standard fire exposures that differ from those currently used.

Affected National and International Standards:  ASCE-7, AISC Specifications, ACI 318, and ASCE/SFPE 29 for fire resistance design and retrofit of structures;  NFPA, SFPE, ASCE, and ISO TC92 SC4 for building-specific multi-compartment, multi-floor design basis fire scenarios;  and ASTM, NFPA, UL, and ISO for new test methods.  Model Building Codes:  The performance standards should be adopted as an alternative method in model building codes by mandatory reference to, or incorporation of, the latest edition of the standard.

NIST WTC Recommendation 10.

NIST recommends the development and evaluation of new fire resisting coating materials, systems, and technologies with significantly enhanced performance and durability to provide protection following major events.  This could include, for example, technologies with improved adhesion, double-layered materials, intumescent coatings, and more energy absorbing SFRM’s.*  Consideration should be given to pre-treatment of structural steel members with some type of mill-applied fire protection to minimize the uncertainties associated with field application and in-use damage.  If such an approach were feasible, only connections and any fire protection damaged during construction and fit-out would need to be field-treated.  Affected Standards:  Technical barriers, if any, to the introduction of new structural fire resisting materials, systems and technologies should be identified and eliminated in the AIA MasterSpec, AWCI Standard 12 and ASTM standards for field inspection, conformance criteria, and test methods.  Model Building Codes:  Technical barriers, if any, to the introduction of new structural fire resisting materials, systems, and technologies should be eliminated from the model building codes.

[ * F-34  Other possibilities include encapsulation of SFRM by highly elastic energy absorbing membranes or commodity grade carbon fibre or other wraps.  The membrane would remain intact under shock, vibration, and impact but may be compromised in a fire, yet allowing the SFRM to perform its thermal insulation function.  The carbon wrap would remain intact under shock, vibration, and impact, and possibly under fire conditions as well.]

NIST WTC Recommendation 11.

NIST recommends that the performance and suitability of advanced structural steels, reinforced and pre-stressed concrete, and other high-performance material systems be evaluated for use under conditions expected in building fires.  This evaluation should consider both presently available and new types of steels, concrete, and high-performance materials to establish the properties (e.g. yield and ultimate strength, modulus, creep behaviour, and failure) that are important for fire resistance, establish needed test protocols and acceptance criteria for such materials and systems, compare the performance of newer systems to conventional systems, and the cost-effectiveness of alternative approaches.  Technical and standards barriers to the introduction and use of such advanced steels, concrete, and other high-performance material systems should be identified and eliminated, or at least minimized, if they are found to exist.  Affected Standards:  AISC Specifications and ACI 318.  Technical barriers, if any, to the introduction of these advanced systems should be eliminated in ASTM E 119, NFPA 251, UL 263, ISO 834.  Model Building Codes:  Technical barriers, if any, to the introduction of these advanced systems should be eliminated from the model building codes.

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2009 Camberwell Fire – Today’s Fire Engineering Challenges

Posted by CJ Walsh

In Ireland, it is rarely the case that there is an opportunity to practice Rational, Evidence-Based Fire Engineering … and to apply its Principles in a manner which is both professional and project-specific.  The grim reality of everyday fire consultancy revolves around playing ‘cat and mouse’ with current national building and fire regulations/codes … with ‘cost effectiveness’, i.e. to achieve a defined objective at the lowest cost, or to achieve the greatest benefit at a given cost … being the real, hidden driver behind such dangerous games !   Who wants to hear that the Irish Fire Safety Certification System is little more than a charade … an elaborate, resource consuming paper exercise … made all the more meaningless because Part B: ‘Fire Safety’ (of the Second Schedule to the 1997 Building Regulations, as amended) is isolated from a necessary and vital consideration of the other Parts, particularly Parts A: ‘Structure’; D: ‘Materials & Workmanship’; K: ‘Stairways, Ladders, Ramps & Guards’; and M: ‘Access for People with Disabilities’ ?

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Colour photograph showing an external view of Lakanal House, Sceaux Estate, Camberwell, London (GB) ... after the Fatal Fire which occurred at 16.19 hrs, on 3rd July 2009. The fire was caused by a faulty television set, and resulted in the loss of 6 lives, with 15 residents and 1 firefighter left injured. London Fire Brigade was required to assist the evacuation of a further 40 building occupants to safety. Along with the serious loss of life, and the large number of injured people ... over 90 families had to vacate their flats.
Colour photograph showing an external view of Lakanal House, Sceaux Estate, Camberwell, London (GB) ... after the Fatal Fire which occurred at 16.19 hrs, on 3rd July 2009. The fire was caused by a faulty television set, and resulted in the loss of 6 lives, with 15 residents and 1 firefighter left injured. London Fire Brigade was required to assist the evacuation of a further 40 building occupants to safety. Along with the serious loss of life, and the large number of injured people ... over 90 families had to vacate their flats.

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Discussing the Principles of Fire Engineering … and elaborating on the significant differences between the limited Fire Safety Objectives of legal regulations/codes … and the much broader range of Fire Engineering Design Objectives intended to fully protect social wellbeing and the interests of clients/client organizations, i.e. to properly protect their asses and their assets, in the event of a fire … is a constant, tortuous, but rewarding, struggle.  Masochism does help !

However, the 2009 Fire in a High-Rise Flat Complex at Camberwell, London (GB) … from just looking at the photograph above and reading available information about the spread of fire internally … raises some challenging fire engineering issues for building designers, property managers and construction organizations.

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1.  Reliability of People Strategies in a Fire Emergency ?

In spite of the People Strategies elaborated in current Fire Codes/Regulations/Standards … it is totally and utterly irresponsible to advise people to wait in their own flats/apartments during a fire incident, or to develop fire safety strategies based on this approach … unless the confidence level (of ‘Competent Persons’ in Control … managers, designers and builders … of the flat/apartment complex) with regard to the following aspects of construction is very high …

  • reliability of both passive and active fire protection measures ;
  • reliability of fire compartmentation (see below) ;
  • reliability of not just the building’s structural stability, but also its serviceability, during the fire and for a minimum period of time afterwards, i.e. the ‘cooling’ phase.

Competent Person:  A person capable of making sound value judgements in the area of professional  endeavour in which he/she possesses profound knowledge, understanding and practical experience.

Fire Codes/Regulations/Standards, wherever or whatever their origin, are NOT Infallible … and it is unbelievably mind-boggling, and sad, to witness a blind and unquestioning faith in such documents !

Looking beyond the headline figure of 6 Fatalities in the 2009 Camberwell Fire … adequate attention should also be focused on the 16 Injured … comprising building occupants and firefighters … the lengthy disruption of community wellbeing resulting from the fire … 90 Families had to be re-located … and, of course, the tremendous amount of direct and indirect damage to property and the environment.  And, I wonder … how did the more vulnerable occupants … and there may also have been visitors present in the complex at the time … cope in this emergency situation ?

This is why Fire Safety, Protection and Evacuation for All must be a Priority on any ‘Sustainability’ Agenda. 

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2.  Independent Technical Control of AHJ Construction ?

I have said this before, but it is worth repeating here again … Self-Regulation Is No Regulation !   Surely this lesson has been burnt into our souls, following the recent scandals, financial and otherwise, in Ireland ?   National and Local Authorities Having Jurisdiction (AHJ’s) … Government Departments & Agencies, Semi-State Organizations, a myriad of Qwangos, the Office of Public Works and Local Authorities are complacent, careless and stubborn concerning proper compliance with even the minimal performance requirements specified in fire regulations, codes and standards.

The 2005 & 2008 National Institute of Standards & Technology (USA) Reports on the 9-11 WTC Incident in New York presented us with some stark language … and a set of important Recommendations which must be heeded …

‘ 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.

To gain broad public confidence … 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.’

[2005 NIST Final Report on WTC 1 & 2 Collapses – Recommendation No. 25]

Later posts, here, will examine the individual NIST Recommendations in more detail.

However … many individuals and organizations, with vested interests, are still trying to discredit and/or ignore the Recommendations contained in the 2005 & 2008 NIST Reports on the WTC 9-11 Incident.   British Standard BS 9999:2008 is a typical case in point … a document which is slowly seeping into the marrow of the Irish Fire Establishment.  The complete and abject failure to consider any of the NIST Recommendations during the long development of this British Standard, or even to reference the Reports in the Standard’s Bibliography … was an inexcusable and unforgivable technical oversight.  The result was … and remains … a sloppy, crassly inadequate, deeply flawed and discriminatory national fire safety standard.  The British Public deserves far better !

At this stage … reluctantly … I must invite the Chair of British Standards Institution Committee FSH/14, Mr. David B. Smith, to seriously re-consider his position. 

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3.  Fire Resistance, Compartmentation & Fire-Induced Progressive Collapse ?

Every person participating in the design, construction, management or operation of a building, no matter how simple or complex, must have a working knowledge and proper understanding of the Fire Engineering Principle of Fire Compartmentation:

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 ;

–   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.

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BUT … But … but … buildings are no longer designed and constructed, today, as they were in the 18th or 19th Centuries …

In a fire situation, Fire-Induced Progressive Collapse may commence before any breach of ‘integrity’ occurs in the boundary of such a Fire Compartment, i.e. the building compartment of fire origin.

Fire-Induced Progressive Collapse:  The sequential growth and intensification of distortion, displacement and failure of elements of construction in a building – during a fire and the ‘cooling phase’ afterwards – which, if unchecked, will result in disproportionate damage, and may lead to total building collapse.

… which is related to, but distinguishable from …

Disproportionate Damage:  The failure of a building’s structural system … (i)  remote from the scene of an isolated overloading action ;   and (ii) to an extent which is not in reasonable proportion to that action.

Structural Fire Engineering:  Those aspects of fire engineering concerned with structural design for fire, and the complex architectural interaction between a building’s structure and fabric, i.e. non-structure, under conditions of fire and its aftermath.

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AND … And … and … a designer of a Sustainable Building will want to utilize … in order to conserve energy … natural patterns of air movement for heating or cooling.  This means that it will be necessary to have gaps between elements of construction which are continuously open … in direct conflict with the Principle of Fire Engineering just quoted above !

What happens when this sort of conflict … or lack of resolution (!) … occurs in modern, highly energy-efficient construction projects ?   At the final stages of approval/certification … the Fire Prevention Officer will insist on following the outdated prescriptive approach in his/her rulebook.  In other words, he/she will illegally apply the guidance text of Technical Guidance Document B as if it were prescriptive regulation.  Fire Compartmentation will be uncompromisingly slapped onto ‘unresolved’ areas of a completed building design … to achieve the limited Fire Safety Objectives of Building Regulations … and the fire safety related construction will probably be badly executed, anyway, because the un-supervised sub-contractors of sub-contractors of sub-contractors couldn’t care less if it goes one way or the other !   The outcome is … nobody wins !!!

In Sustainable Building Design, therefore, Fire Resistance (a ‘passive’ protection concept) must not only be extended to consider a complementary relationship with ‘active’ fire protection concepts, but be stretched … ‘intelligently’ … to embrace the concept of ‘non-construction’ …

Building Sterile Space (Fire):  An open space of sufficient and appropriate extent which is designed to retain an exceptionally low level of fire hazard and risk, and is ‘intelligently’ fitted with a suitable fire suppression system – in order to resist and control, for a specified time during a fire, the advance of heat, smoke and flame.

Fire Resistance:  The inherent capability of a building assembly, or an element of construction, to resist the passage of heat, smoke and flame for a specified time during a fire. 

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Concrete Testing Fraud in New York – 1 World Trade Center

Posted by CJ Walsh

2009-09-09 …

Background & Verification

Early 2008 … a New York Inquiry into the Concrete Testing Industry begins.  At issue is the Structural Reliability of Current Major Public Works Projects in the City, including many Tall Buildings.

Current Internet Search: ‘New York Concrete Testing Inquiry’ … to discover the full measure of fraud and corruption.

I wonder how the U.S. Model Building & Fire Code Organizations … including the U.S. International Code Council … are responding to this growing scandal in New York.   Are they responding at all ?   AND … do they discuss this sort of issue openly, as they heavily ‘promote’ the adoption of U.S. Codes in Developing Countries around the world ?

What is the position of the Council on Tall Buildings & Urban Habitat (CTBUH) ???

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2009-09-08 … by Niki May Young, News Editor, World Architecture News(.com) …

Robert LiMandri, New York’s Buildings Commissioner, has announced that concrete tests are to be carried out on 82 New York buildings following safety concerns arising from the indictment of Testwell Laboratories in January and a further firm in July.  Testwell were accused of falsifying concrete mix design reports for the high profile Freedom Tower Project (now 1 World Trade Center), Yankees Stadium, Jet Blue Terminal and a number of other projects and had their license suspended.  Stallone Testing Laboratories were also indicted for falsifying concrete mix design reports in July.

The indictment of Testwell led to a lack of confidence in the safety of over 100 buildings in New York.  Following investigations, 82 buildings are to be re-examined.  The investigations come as part of an announcement by LiMandri of a new comprehensive program to increase the oversight and evaluation of concrete testing at construction projects throughout the City, including projects funded by the City and private developers.  The program includes plans to build a city-owned and operated concrete-testing laboratory and the creation of a new Concrete Unit at the Department Of Buildings (DOB).

The new City laboratory, which will be operated by the Department of Design & Construction (DDC) and is expected to open as early as January, will offer testing services to all City agencies responsible for construction projects.  New York City has 35 private concrete-testing firms currently licensed to do business in the City and the new facility will also make it possible to audit these firms.

“Concrete testing is a critical component of concrete operations, and the results should affirm the strength and quality of materials used for a building under construction,” said LiMandri.  “However, the integrity of concrete-testing practices has come into serious question, and this new laboratory, as well as a new Concrete Unit and re-testing protocol, are three significant measures to ensure concrete testing procedures are lawful and the concrete used meets a project’s specific design requirements.”

DOB denied Testwell’s application to renew its concrete-testing license but a State Supreme Court Judge rejected DOB’s denial of the license renewal.  DOB is now appealing that decision.  Last Friday, DOB revoked Stallone’s concrete-testing license, prohibiting them from testing concrete in the City.  The Department Of Buildings is currently working with property owners named in the Stallone indictment to determine whether a project’s final test results meet the structural design requirements.  If they do not, the affected property owners will also be required to follow the re-testing protocol.

“New Yorkers must be confident the City’s buildings have been built to exacting standards and that the concrete, not usually visible, was mixed to proper construction specifications,” added Design and Construction Commissioner Burney.

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