The Windsor Tower, Madrid fire
This fire is one of the fires Conspiracy theorist like to point to when talking
about high raise office fires. This fire lasted 26 hours.
But what they don't tell you is that the first collapse
happened only 2 hours and 30 minutes after the fire began.
But why didn't the building fall completely? It was on fire for 26 hours. The answer is very simple. The building were
constructed very differently than the WTC. Reinforced concrete was used in the
core and under the 17th floor. Below are detailed descriptions of how the Madrid
tower was constructed and the reason for it not collapsing...
What you see above is the
concrete reinforced core. What's missing is the steel around
the core of the upper floors which was not covered in
concrete. As with the towers, it weakened and collapsed
early in the fire.
The building totaled 32 story's, with 29 floors above ground
and three below. A concrete core and concrete frame supported the first 16
floors. Above that was a central support system of concrete columns, supporting
concrete floors with steel perimeter columns. An additional feature was the
presence of two 'technical floors' - concrete floors designed to give the
building more strength. One was just above the ground level and the other at the
The fire protection on the
existing steelworks below the 17th floor had been completed
at the time of fire except for the 9th and 15th floors. When
the fire spread below the 17th floor, those protected
perimeter columns survived, except for the unprotected
columns at the 9th and 15th floors which all buckled in the
multiple floor fire (see Figure 2). However, they did not
cause any structural collapse. Obviously, the applied
loads supported by these buckled columns had been
redistributed to the remaining reinforced concrete shear
walls. Nevertheless, structural fire analysis should be
carried out before such a conclusion can be drawn.
A survey of the fire
damaged structure of the Windsor Tower, Madrid, has
concluded that the concrete structure “performed
extraordinarily well in a severe fire”. The study, ‘Fire
in the Windsor building, Madrid: Survey of the fire
resistance and residual bearing capacity of the structure
after the fire’ was carried out by the Spanish Instituto
Technico de Materiales y Construcciones (INTEMAC). It
underlined the need for fireproofing structural steel
concluding that the “need for fireproofing of steel members
to guarantee their performance in the event of fire was
The Windsor Tower fire
started on the 21st floor of the 32 storey building in
February 2005. The fire quickly spread due to a lack of fire
stops between the curtain wall façade and the concrete floor
slabs. Designed and built in the 1970s, the tower was built
using traditional design methods. Extensive refurbishment
was underway at the time of the fire. Ironically, part of
the refurbishment programme was to bring the building’s fire
standards up-to-date with the installation of active fire
prevention and resistance measures.
failure happened with the collapse of the steel perimeter
columns which resulted with the floor slabs collapsing as
the edge support was taken away. The massive concrete
transfer slab at the 20th floor prevented further
The building had a
concrete central core with two rows of reinforced concrete
columns in the north-south direction, aligned with the
core side walls. The structure above ground was
characterized by two transition floors at 3rd and 17th Floor
levels, which housed plant and services.
The typical floor slab
construction was reinforced concrete bi-directional ribbed
slabs, spanning onto composite steel beams in the east-west
direction. The slabs were supported along the perimeter by
steel columns, supplemented by reinforced concrete columns
on two sides below 17th Floor level.
The transition floors were
formed with solid RC slabs and deep beams. The original
facade mullions and transoms were fixed to the steel
perimeter columns, and a new facade structure had been added
to outside of old facade. The perimeter columns in turn were
supported by transition structures at 17th and 3rd Floor
The central concrete core appeared to
perform well in the fire and on initial observations seems
to have played a major role in ensuring the stability of the
building throughout the incident. The role of cores in
multiple floor fires is now an immediate area of study
required for the industry, and Arup have commenced
investigating this issue.
assessment of this structural design, an understanding of
why the structure performed as it did and why total collapse
did not occur would provide valuable information for future
structural fire analysis in design.
It would assist in the strong
move now towards structural fire engineered buildings, and
therefore help with the move away from reliance on Building
Code based single element testing and associated fire
proofing techniques which do not address real and structural
behavior in real fires.
Recently the conspiracy
theorist have begun using another building to use as a
The Parque Central was a 56
storey government office building in
fire started on the 34th floor and climbed to the 47th
floor. That's not similar to the WTC 7 because the fires
were on the lower levels. The building didn't have a tube in
a tube design like any of the WTC buildings either.
The single most important
difference are in the columns.
The reinforced concrete structure
consists of perimeter columns connected by
post-tensioned concrete “macroslabs” that are each
10 feet (3 meters) deep and above the second–floor
mezzanine, the 14th, 26th, 38th, and 49th floors.
There’s no central core.
Individual floors between the
macroslabs have a steel-deck floor supported by steel
beams, all protected underneath with spray-on Cafco
Blaze Shield DC/F mineral glass fiber wool with cement
fireproofing. According to Cafco’s Manny Herrera,
the floor was designed to meet U.S. standards for a two-hour fire
resistance rating. However, the overall fire
compartmentalization of each floor slab was decreased by
the addition of several unrated floor panels to provide
access to mechanical and plumbing systems.
Five structural bays rest on four
lines of columns in each direction supporting the steel
deck. In effect, the concrete structure includes five
stacked steel buildings, each supported by a macroslab.
During the fire, two steel decks partially collapsed;
other than that, there was no collapse inside the
building. However, deflection in some steel beams was
The fire was also
aggressively fought for a period of time.:
at the scene decided to bring a 2-inch (63-millimeter)
hose line, fed by fire engines at the ground level, all
the way up one of the fire stairs. Two portable booster
pumps, each flowing 264 gallons per minute (gpm) at 58
psi (1,000 liters per minute [lpm] at 4 bar), were used
to provide adequate pressure above the fire floor.
approximately 1:15 a.m., firefighters working with two
1-inch (38-millimeter) hose lines from different
locations above the 34th floor were able to slow the
upward movement of the fire considerably. By 3 a.m.,
a second 2-inch (63-millimeter) hose line, identical to
the first one, had been put into service, and
firefighters confined the fire to three to four floors
above the 34th floor. This approach was successful
through the first five or six hours of the fire, when
the fire spread vertically at a rate of approximately
one floor every three hours. The 27th floor became the
main staging area for about 100 firefighters.
At 7 a.m.,
some of the booster pumps started to malfunction, and
the fire regained intensity, spreading vertically at a
rate of about one floor per hour until approximately 10
a.m. Around 11 a.m., the fire breeched the fifth
macroslab, below the 39th floor, and around noon, the
stairwells’ fire enclosure started to fail. Concerned
that the building might collapse, the fire chief
immediately ordered that interior firefighting
operations be abandoned. It should be noted that the
CFD only reported minor injuries among its personnel
during this risky operation.
continued to move upwards through the afternoon, at a
rate of about 2 1/2 floors per hour. Between 2 and 3
p.m., the Venezuelan government began using helicopters
with water buckets, commonly used on forest fires, in an
unsuccessful attempt to slow the fire down.
eventually burned itself out at 3 a.m. on Monday
morning, after spreading and consuming the contents of
some 17 floors, more than 24 hours after it began.
Past history and
performance shows that this fire could probably have
been controlled quickly by a standard wet-pipe sprinkler
system and that the fire department’s chances of
controlling the fire at, or a few floors above, the
floor of fire origin would have increased if the
standpipe system had been working. This fire highlights
the importance of periodic inspection, testing, and
maintenance of fire protection systems, as well as the
importance of strictly following manufacturers’
incident once again reminds us of the fire safety
challenges high-rise buildings present and demonstrates
that no fire department, no matter how large,
professional, and well-equipped, can effectively control
a fire without properly designed passive and functioning
active fire protection systems. The CFD performed
admirably in an impossible task, and its commanders made
difficult decisions that ultimately proved to be the
and building 7 were essentially bolted together like an
erector set. No concrete was used to create a ridged block
or protect the columns. The steel webbing was pushed to the
challenge to conspiracy theorist:
a steel frame building at least 40 stories high
Which takes up a whole city block
is a "Tube in a tube" design
Which came off its core columns at the bottom floors
(Earthquake, fire, whatever - WTC 7)
Which was struck by another building or airliner
and had structural damage as a result.
weakened by fire for over 6 hours
which had trusses that were bolted on with two 5/8"
after all seven tests are met the building didn't fall
Anything less than meeting these seven tests is
dishonest because it's not comparing apples with apples.
Showing a much lighter 4, 5 or even 15 story building
which doesn't even take up a city block, and has an old
style steel web design leaves out the massive weight the
47 story WTC 7 had bearing down on it's south face
columns. Yes, this is "moving the bar" back to where it
should have started.
an absurdity to expect these buildings to perform the
same during a collapse. This is why it's the first time
in history these buildings fell as they did. It's the
first time in history buildings constructed like this
So what have we learned from
the conspiracy theorist? Something the NIST realized long
ago. Concrete makes good insulation.