The fact that no steel framed buildings before or since 911 have collapsed as a result of fire is a point worthy of note. Let's call it observation and experience, or empiricism. Three in one day and never before or since? This seems to, er, contradict all previous observations. One would naturally assume that some oversight had been made and that new guidelines should be put in place, new standards to ensure this can't happen again. I don't recall any such revisions to the construction of steel framed high rise building.
[ex=http://www.nist.gov/el/disasterstudies/wtc/upload/WTCRecommendationsStatusTable.pdf]
(IBC) Provides minimum structural integrity for framed and bearing
wall structures through continuity and tie-force requirements for buildings over 75 ft.
in height that represent a substantial hazard to human life in the event of failure (e.g.,
buildings with occupant loads exceeding 5,000) and essential facilities, such as
hospitals.) This code change is intended to enhance overall structural integrity but is
not intended to prevent progressive collapse in structures.
(IBC) Increased by one hour the fire-resistance rating of structural
components and assemblies in buildings 420 feet and higher.
This change was
approved and included in the 2004 supplement to the IBC and later in the 2006 IBC
(section 403.3.1, Item 1).
(National Electrical Code) Article 708 of the 2008 National Electrical Code addresses
critical operations power supply. The article can be applied to any critical systems.
(IBC) Increased bond strength for fireproofing (nearly three times
greater than currently required for buildings 75-420 feet in height and seven times
greater for buildings more than 420 feet in height). The increased fireproofing bond
strength is required to be "installed throughout the building."
Field installation requirements for fireproofing to ensure that:
installation complies with the manufacturer's instructions;
the substrates (surfaces being fireproofed) are clean and free of any condition
that prevents adhesion;
testing is conducted to demonstrate that required adhesion is maintained for
primed, painted or encapsulated steel surfaces; and
the finished condition of the installed fireproofing, upon complete drying or
curing, does not exhibit cracks, voids, spalls, delamination or any exposure of
the substrate.
Special field inspections of fireproofing to ensure that the as-installed thickness,
density and bond strength meet specified requirements, and that a bonding agent is
applied when the bond strength is less than required due to the effect of a primed,
painted or encapsulated steel surface. The inspections are to be performed after the
rough installation of mechanical, electrical, plumbing, sprinkler and ceiling systems.
(ASTM) ASTM E2584-07 "Standard Practice for Thermal
Conductivity of Materials Using a Thermal Capacitance (Slug) Calorimeter."
(IBC) Explicit adoption of the "structural frame" approach to fire
resistance ratings that requires all members of the primary structural frame to have the
higher fire resistance rating commonly required for columns. The primary structural
frame includes the columns, other structural members including the girders, beams,
trusses, and spandrels having direct connections to the columns, and bracing members
designed to carry gravity loads. The definition of the primary structural frame was
broadened to include bracing members essential to vertical stability (e.g., floor systems
or cross bracing) whether or not they carry gravity loads.
(NFPA) The structural frame approach is mandated in the 2006 edition of NFPA 5000.
(NIST) Published “Best Practice Guidelines for Structural Fire
Resistance Design of Concrete and Steel Buildings,” (NIST TN 1681)
(IBC) Requires greater reliability of sprinklers with a minimum of
two water supply risers for each sprinkler zone in buildings over 420 ft. in
height. Each riser is required to supply sprinklers on alternate floors. The sprinkler
risers are to be placed in stair enclosures which are remotely located.
[/ex]
There's a bunch more, but they are mostly to do with evacuation and firefighter access.
Specific to the ICC:
[ex=http://www.iccsafe.org/newsroom/Documents/08302011-911.pdf]
Building Safety Codes Changed as a Result of 9/11
Changes to the International Codes as a result of 9/11 include:
Elevators are required in high-rise buildings more than 120 feet tall so firefighters
can get to, and fight fires, without walking up from the ground floor with heavy
equipment;
An additional stairway for high-rises that are more than 420 feet tall;
In lieu of the additional stairway, an option to provide enhanced elevators that can
be used by the building occupants for emergency evacuation without waiting for
assistance from emergency personnel;
A higher standard for fire resistance in high-rise buildings more than 420 feet tall;
More robust fire proofing for buildings more than 75 feet tall, which will be less likely
to be dislodged by impacts or explosions;
Shafts enclosing elevators and exit stairways that have impact resistant walls;
Self-luminous exit pathway markings in all exit stairways that provide a lighted
pathway when both the primary and secondary lighting fails; and Radio coverage systems within the building to allow emergency personnel to better
communicate within the building and with emergency staff outside the building
supporting the response.
[/ex]
Specific to the NFPA:
[ex=http://www.nfpa.org/publicJournalDetail.asp?categoryID=2248&itemID=53000&src=NFPAJournal&cookie_test=1]
Looking at the potential impact that changes to its codes and standards could have, NFPA gathered a team of engineers, architects, fire service officials, and public advocacy groups to form the High-Rise Building Safety Advisory Committee (HRBSAC) in 2004. The committee was formed to develop public proposals and comments primarily for NFPA 1, Fire Code; NFPA 101®, Life Safety Code®; and NFPA 5000®, Building Construction and Safety Code®. The committee also helped NFPA set priorities for the NIST recommendations.
NFPA has acted on a variety of the NIST recommendations. The behavior of a building’s structural frame and support system as a whole under severe loading conditions, such as during a fire event, resulted in adoption of the "structural frame" approach in NFPA 5000, which requires more scrutiny of the primary and secondary structural members, as well as the connections that tie the frame together.[/ex]