On Nov 6, 3:51 am, Geoff wrote:
On Mon, 05 Nov 2007 05:45:06 -0800, wrote:
On Nov 5, 5:02 am, Geoff wrote:
On Sun, 04 Nov 2007 03:31:03 -0800, wrote:


snip

An office mockup test at Cardington gave an average temperature of 900 deg
and a maximum of 1200 deg C. The unprotected steel reached 813-1150 deg C,
which is PLENTY hot enough to turn it into cooked spagetti.http://guardian.150m.com/fire/small/...m(abouthalfway down the page)
I could probably get the actual test data if I asked for it.

Sorry but you won't do it in 56 minutes.

Wanna bet?

Yep.

Plenty of scientific evidence says otherwise.

Please point it out. What evidence is there that WTC2 reached
temperatures of, say, even 500 degrees C, over any appreciable area.

The WTC fires were
much more severe any conventional fire for a building of the type =
multiple starts, much extra fuel, no suppression, etc.

Other buildings have burnt much longer, e.g., 18 hours, in fires that
were indisputably larger in extent and obviously much more intense
than anything WTC2 could have experienced, yet they never collapsed.

http://web.archive.org/web/200402160...n/meridian.htm




A well known accidental fire was Broadgate in the UK. It was a conventional
office building with steel framing, concrete slabs on steel beams. The
building was under construction and hadn't had the fire rating applied. A
fire broke out in a site shed, and was enough to severely deform the beams
and columns. The building didn't collapse due to moment redistrbution of
the load, thanks to the design of the building, with welded and pinned
joints and multiple columns. The WTC was different, with the central core
and perimeter columns, it relied on the connections at each end of the
trusses. When either the connections failed, or the trusses twisted so the
load was no longer correctly supported, it was all over.
The temperature was estimated to be around 1100 deg C for the Broadgate
fire.
More info on real fires and temperatures at:http://www.modernsteel.com/Uploads/I...7_01_fire.pdfh......
I suggest Andy Buchanan's fine bookhttp://www.amazon.com/Structural-Design-Safety-Andrew-Buchanan/dp/047...

A key difference between the WTC and natural fires was the development of
the fire. In a normal fire, it will start at a single point of ignition -
say an overheated computer, and spread through the floor as neighboring
items ignite until the upper layer temperature is enough to cause radiation
on the floor to induce flashover. In this case, a significant amount of jet
fuel started fires everywhere. Even if some jet fuel was burnt outside the
building, not every drop was burnt outside, and the radiation of the huge
fireball would have been enough to start fires anyway.

Even if "SOME" burnt outside the building? Well the videos are
available on youtube. The videos speak for themselves. Apparently
you've got it backwards: if SOME actually burnt inside the building
(in the case of WTC2 at least) it wasn't much.

IIRC, NIST did their simulations assuming something like 40% burnt in
the building, and as I recall, they never explained how they arrived
at that figure...and to the extent they're wrong about important
initial conditions, their whole simulation is wrong.


Bull****. It's plain to see *from simple calculations* that MOST if
not ALL of the jet fuel went up in a cloud outside WTC2.
The size of the fireball basically accounts for ALL the fuel...if any
was left inside it was probably an insignificant amount.

But the fact is it wouldn't have mattered if you filled the whole
****ing building up with the hydrocarbon fuel of your choice, you
simply cannot burn enough fuel in 56 minutes time (without a specially
constructed apparatus) to heat 2E6 kg of construction materials up to
600 - 700 degrees centigrade.

You don't have to heat the whole building up, only the important bits.

Not if you're using judiciously placed thermite and/or explosives, you
don't. If you're going to depend on randomly scattered fires then you
would generally have to, no? Unless you're going to claim that somehow
by magic, the fire/heat only went where it needed to go to cause
collapse? Last time I cooked a pie in the oven, I had to waste energy
heating the inside walls of the oven and even the room itself, to a
certain extent. If you've found a way to only heat what you want, what
are you doing working? Why aren't you out cruising the Caribbean on
your yacht, for example?

That
is why fire protection is added to steel beams. it isn't to make some
applicator companies rich you know. If it wasn't necessary, it wouldn't be
done.

In what sense is it deemed "necessary" and how do *you* personally
know it's "necessary"?

If the connections fail or the trusses deform in the fire room, then they
will collapse. The load will be transferred to other members, and hopefully
the whole lot will stay up, although the floor might sag and everything
bends a bit. Take out half the structure when half the supporting structure
is demolished by a plane, add lightweight trusses that can't take an
eccentric load due to the missing supports so they twist,etc, and it is all
over.
By definition the insulation criteria for fire walls means the mean
temperature on the cold side of a fire wall is less than 140 deg C (180
maximum at any point), yet the room or furnace on the other side can be
over 1000 deg C. And yes, I have seen this very event and have photos to
prove it. It was a plasterboard wall in the testing furnace at BRANZ. You
are right - it would be impossible to heat the entire building up,
unfortunately you don't have to. If you did, you wouldn't need to do have
any fire protection at all.

Well how effective will insulation be after a fire burns for many
hours? The "One Meridian Plaza" fire burnt for 18 hours and involved
many floors, seven of those hours without any firefighting efforts at
all. According to "Simpson Gumpertz and Heger", "the twelve-alarm fire
burned for 18 hours. The extreme heat caused window glass and frames
to melt and concrete floor slabs and steel beams to buckle and sag
dramatically."

Let's see, if the steel beams "buckled and sagged dramatically", then
either the beams weren't insulated or the insulation wasn't much good,
no? Yet the building still didn't collapse.


The multiple fire
starts are the reason why the fire reached a peak sooner and hotter than
might have been the case in an accidental fire.

Bull****.

Accidental fires grow exponentially. Typical upholstered furniture fire
growth is fast - heat release rate around 0.466*t^2 where t = seconds, HRR
will reach 1MW in around 150 seconds. A typical 3 seater couch is around
3-3.5MW peak HRR - it is like having a can of petrol in your living room.
With multiple ignitions you don't have that growth , or and incipient
smouldering. I have also been inside a house on fire, and outside at
flashover on several fires. It takes no great science to understand fires
are hot when you have been up close and personal to them or seen the
aftermath.
G

Well, yes, assuming you have enough oxygen available. You can't get MW
of heat for any length of time without lots of airflow. You may have
adequate air near a broken widow or hole in the wall, but what about
everywhere else? You can't do it in 56 minutes.