Re: Structural failure of NY's WTC

[Bernard Cleyet <anngeorg@PACBELL.NET>]

I should have cross posted  the following I posted Fri., Sat., and Sun.

Note the detailed description available as a link on the Californian site.

bc



---- Original Message --------
Subject: Re: Final ''off topic'' thoughts about last week
Date: Fri, 14 Sep 2001 19:24:31 -0700
From: Bernard Cleyet <anngeorg@pacbell.net>
To: tap-l@listproc.appstate.edu
References: <l03130305b7c829db9cd0@[130.92.1.54]>

Sorry.  Here's another thought:

"Empire State wins ‘millennium’ award The Empire State Building, which lost its
status as the world’s tallest building years ago, has been named as one of the
10 greatest engineering achievements of the 20th century.  The American
Society of Civil Engineers recognised the skyscraper as “an outstanding
example of engineering ingenuity and dedication that inspired the world to
build taller and taller buildings”.  Other winners of the “Monument of the
Millennium” award from the engineering organisation include the Panama Canal,
the Golden Gate Bridge in San Francisco, Kansai International Airport in
Osaka, Japan, and the California State Water Project.  The 102-storey
structure, completed 70 years ago, was built by 3,000 men in just a year and
45 days. Its elevators can take visitors to the top observation deck in less
than a minute; its construction is so sound that no structural damage occurred
when a B25 bomber crashed into it in 1945."

bc

P.s.  From what I've been able to find in a google search (above included),
the claim of structural soundness may be negated, because it wasn't a direct
hit, .  A radio architect claims that if std. construction, instead of "cut
corners", had been used, there would've been no collapse, and, therefore, loss
(life and property) would have been ~< 10% of .....  I wonder if the
terrorists were aware of the towers' probably unique vulnerability.

I won't make explicit the implied political comment.

P.p.s. I quite agree with Urs' thoughts!    The level of jingoism Gate Keeper
has encountered, even in the staff room of the Elementary School where she
teaches, is very sobering.

cut ---

Subject:
            Re: Final ''off topic'' thoughts about last week
      Date:
            Sat, 15 Sep 2001 22:51:35 -0700
      From:
            Bernard Cleyet <anngeorg@pacbell.net>
        To:
            tap-l@listproc.appstate.edu
 References:
            1 , 2 , 3 , 4 , 5 , 6




I will add to my Friday post, wherein I wrote that a "radio" architect said it
failed because the builders "cut corners."

This is only from memory.  (My tape recorder shut off in the middle of the
discussion.)  He said --  the std. method is to encase the structural elements in
concrete, not only for compressive strength, but also to insulate.  At 1600 deg
steel loses its strength.  In particular the floors were "bar joists" prefab'ed in
NJ and brought over by barges.  The planes blew off the sheet rock and left them
vulnerable to the kerosene fire.  He said one could see the ripple of the
collapsing floors pull in the sides of the buildings.  It all doesn't make complete
sense to me, however, I intend to talk to the host and producer of the program to
get the address of the architect.  He was a Harvard grad. student (M.E.) at the
time, and then could see a problem.  It reminds me of two things:  While I was the
sheet metal person on a team building a luxury home in an exclusive part of Santa
Barbara, the builder/engineer said fireman would much rather enter a large wooden
beamed building than a steel beamed one, because the wood was self insulating (even
GK understands this from fireplace experience), while steel will soften.  He also
said sometimes builders wrap the beams with asbestos.  This was in '73, my first
job after returning from Chile (more about this in a later post), so remember, I
suffer from CRS.  Secondly when I was in England (late 60's), a residential tower
block suffered a gas explosion in one of the flats.  The explosion pushed out the
outside load bearing walls and the upper floors pancaked down.  This was too much
for the floors below (exact physics expression) and the whole thing pancaked.  If I
remember correctly Wislon (Cockburn's moniker for the PM) had the other tower
blocks converted to all electric.  I think this was council housing.


I think, I remember more:  He said the method was (also) to use closely spaced
columns (steel) for load bearing, as opposed to more widely spaced columns in
concrete.

bc

P.s. Also while I was in England the Aberfan disaster occurred, as a result every
one in England learned the meaning of the expression "angle of repose."    (Bloody
Sunday too in N. Ireland)

cut --




No, not rebar joists, bar joists   rebar(ed) joists probably would have held up.  The
bar joist were not reinforced concrete, but
plain bars (beams) covered with sheet rock (the architect said sheet rock).

Below is an example of bar joisting supporting a concrete block floor. (Note  the
".patented ,.. simple and affordable." in the sub title.

http://www.iq-home.com/Documents/j980127%20-%20Floor%20&%20Roof%20with%20Concrete%20Block.pdf

Just now GK called me to look at a page in the local paper (Sat./Sun. ed.) we had
missed.  It has some detail of the construction and their supposition on the cause of
the collapse.  It generally agrees with the radio architect.  i.e. trusses support a
reinforced concrete floor.  Much better would have been prestressed concrete beams,
but they are expensive!

Here's the Californian's site -- in the middle are five special multimedia
presentations.  The second one (points of impact)
conflicts with the architect, the Californian (print ed.) and the forth presentation
(interactive graphic illustrates how...) -- check
that one out.

http://www.californianonline.com/

Have fun and think about the bottom line -- of course I must admit, tho. it (plane
crash) had happened before, would you double the cost of a building to ensure no
collapse?

bc

Final thoughts (this post):  9:50  the first tower collapsed; more than thirty
minutes later the second collapsed (10:29);  how
many initially uninjured and on floors below the explosion survived?  Check out the
poll results on the Californian's "The Big Question."


Urs Lauterburg wrote:

> Dear Tap-lers,
>
> Thank you for the numerous replies on my off topic mail I sent to the list
> on the very dark September 11th 2001. I just had to say something since the
> outrageous incident really affected and and still does affect the way I
> perceive things. It is true that after this terrorist attack on the free
> world's symbols of prosperity and strength, the world will never be the
> same again. The action clearly shows what ruthless violence is all about.
> Certain forms of violence however are accepted and others are not.
> Hollywood movies can be very atrocious at times, slaughterhouses are quite
> brutal too, so is building and dropping bombs in a ''civilized'' way. I
> think history is at a point where the traditional scheme of punishment will
> not solve the worlds problems any longer, even if we try to do it in these
> old ways. It is obvious that mafia ethnic of endless revenges just results
> in a disastrous final state.

cut
> Kind regards to you all
>
> Urs
>
> Urs Lauterburg
> Physics Edutainer
> University of Bern
> Switzerland


brian holton wrote:

   Hey George-

   "cheap NJ rebar" - you may mean poor quality rebar, but I assure you -
   nothing in NJ is cheap, especially the rebar ;)  NY building codes are one
   of the most stringent in the nation.  Contractors and workers took great
   pride in the building they were constructing - I wouldn't blame poor quality
   construction or materials, but rather the more physical aspects you pointed
   to early in your message.

   Now, as far the news reports that the towers were designed to withstand an
   aircraft crash and that the designers did not taking into account modern
   aircraft - I doubt anyone would ever claim that the hits that occurred even
   with the old 707's - direct head on - would not destroy the towers.
   Further - the elderly 707 in it's 320 configuration holds 23,000 gallons of
   fuel, the new kid 757 only 11,300 gallons.  Both have about the same
   airspeed.  The 757 comes in at 125 tons at take-off, the 707 has a gross
   weight of 170 tons.  I guess I'd rather not get hit by either, but fully
   fueled with a more or less direct hit in the right location - either one
   would take down the tower(s).

   Now the big boy 747 comes in at 430 tons and can carry 57,000 gallons of
   fuel (I just adore that plane).  But they are harder to fly and don't fly as
   often.  They've been around before the towers were constructed as well.  I
   think the reporters aren't doing their homework sometimes when they make
   some of their claims, but overall things have been pretty factual I think.

   Brian H.
   NJ Anti-defamation League

   -----Original Message-----
   From: owner-tap-l@listproc.appstate.edu
   [mailto:owner-tap-l@listproc.appstate.edu]On Behalf Of George Collison
   Sent: Sunday, September 16, 2001 9:23 AM
   To: tap-l@listproc.appstate.edu
   Subject: Re: Final ''off topic'' thoughts about last week

   At 12:37 AM -0700 9/16/01, Sean Lally wrote:
   >As I understand it, the heat was so intense that the structure
   >literally melted
   >and then collapsed in on itself.
   >
   .....though the contractor might have been
   using cheap NJ rebar [as suggested in a previous note] .

   George