Paris CDG airport catastrophe

Adam Weiss wrote in message
...
Thomas Peel wrote:
Roof collapsed terminal 2E.

http://www.cnn.com/2004/WORLD/europe...pse/index.html

Looks to me like a sheer connection that failed down at the bottom of
the elliptical roof, where it meets the elevated floor. But I could be
wrong.

What's interesting is that the building opened late because its
certificate of occupancy was witheld thanks to concerns about its
safety. I wonder what made them change their minds. Bribes?

Either way, it was obviously not a good choice. 5 people are dead
because of it.

It's impossible to speculate much with so little to go on, especially when
dealing with a vaulted structure.

From the few photos I've seen, the concrete seemed OK unless the was an
isolated batch of junk that failed and triggered a domino effect that was
limited by expansion joints.

I also noted the external perpendicular bridge that came in at one end of
the collapse. Perhaps the load imposed at that location wasn't adequately
dealt with.

It's a remarkably clean collapse which, to me, indicates a marginal design
flaw that was exposed by transient loading or vibration or material
variations at the extremes of acceptability. My guess is that the flaw will
be discovered and the entire structure will be taken down.... But it's all
speculation.

devil wrote in message ...

Smells like the design may have been just a bit too daring and they ended
up encountering unanticipated problems which are now taking their revenge?

This is what I think. Note the concept was adapted from tunnel construction
where the requirements are to resist a uniform outside pressure. This being
absent, a facsimile was provided by steel bands under tensile stress. But the
external load is now the weight of the structure. It seems like an extremely
complex concept, and I have to wonder how closely it answers to the
orginal inspiration.

I wonder if the properties of the shell weren't parameterized or standardized
in some way that allowed them to calculate the required strengths etc.
but which failed to capture all the salient variables. Perhaps some of
the cross sections underwent more complex stresses than allowed for by
the model, or perhaps the whole structure relaxed into a nonlinear
regime.

At any rate, I bet it's the design.

Lew Mammel, Jr.

"lew" wrote in message
om...

This is what I think. Note the concept was adapted from tunnel
construction
where the requirements are to resist a uniform outside pressure. This
being
absent, a facsimile was provided by steel bands under tensile stress. But
the
external load is now the weight of the structure. It seems like an
extremely
complex concept, and I have to wonder how closely it answers to the
orginal inspiration.

SNIP

At any rate, I bet it's the design.

From what I've read, it isn't a problem with the shell, rather a problem
with some support pillars. They started cracking and were bandaged with
carbon fiber on the outside. Sounds like the Band-Aid wasn't enough. That
may have been the cause of the several-months' delay in opening the
structure.

The structure is reported to have 170-some pillars of this type. I don't
know where the offending pillars are located in the structure or whether a
better fix can be applied.

The shell is reported to have come down pretty much intact.

On Wed, 02 Jun 2004 06:58:22 -0400, R J Carpenter wrote:


"lew" wrote in message
om...

This is what I think. Note the concept was adapted from tunnel
construction
where the requirements are to resist a uniform outside pressure. This
being
absent, a facsimile was provided by steel bands under tensile stress. But
the
external load is now the weight of the structure. It seems like an
extremely
complex concept, and I have to wonder how closely it answers to the
orginal inspiration.

SNIP

At any rate, I bet it's the design.

From what I've read, it isn't a problem with the shell, rather a problem
with some support pillars. They started cracking and were bandaged with
carbon fiber on the outside. Sounds like the Band-Aid wasn't enough. That
may have been the cause of the several-months' delay in opening the
structure.

The structure is reported to have 170-some pillars of this type. I don't
know where the offending pillars are located in the structure or whether a
better fix can be applied.

The shell is reported to have come down pretty much intact.

There are rumors floating around to the effect that sixteen of the pillars
had not actually been reinforced.

Which ADC vehemently denies. But who knows.