Engineering at 911Blogger - will they get it right?

[Oystein]

Haha.
This should get funny:
http://www.911blogger.com/news/2012-08-07/collapse-physics-huge-obvious-error-bazants-work

I found an important error in Bazant's article Why Did the World Trade Center Collapse? — Simple Analysis. To my knowledge, it has not been reported before.

Bazant writes:

[...] the lower part of the structure can be approximately considered to act as an elastic spring.

He calls the stiffness of this spring C and somehow derives the equation

(1) P_dyn / P_0 = 1 + sqrt(1 + (2Ch/mg)) ≈ 31

Just by looking at this so called overload ratio, one can see a huge problem: it grows with C. This is highly implausible because it means that a harder material causes a higher collapse probability.

So far only one other poster commented and asked a question:

I wonder if the phrase "harder material" is imprecise and should be "stronger material" as a harder material could be more brittle and therefore possibly less strong

Let's see if any of the brainiacs there step in to actually defend Bazant and put this fool Duschvorhang (that's German for "shower curtain") in his place

 

[ozeco41]

Given the level of intelligence on display I doubt that they will get responses that address the problem even within the Bazantian assumptions and context.

...and, as anyone posting here knows (should know - I'm being too presumptuous. ) - the real problem is at a higher level.

That is at the level of where Bazant's material does not align with real world WTC 9/11 collapses.

That higher level risk is the one that was the base error of a paper titled 'Missing Jolt' and much posting from the same or related sources.

You cannot validly mix 'bits of Bazant' with 'bits of real world events' unless you are very careful and not many folk get it right.

 

[Oystein]

...
You cannot validly mix 'bits of Bazant' with 'bits of real world events' unless you are very careful and not many folk get it right.

Well of course you can - and they do! They mix the wrong bits of Bazantian ivory tower statics with the wrong assumption of the missing jolt madness and spice that with some very wrong concept of what the "stiffness" of a spring is and means, to cook a spectacular fail stew.

Regardless of all the errors of Bazant, Szamboto NIST or the entire truth movement, someone there should explain to Duschvorhang why a stiffer spring doesn't translate to one that survives higher loads.

 

[Redwood]

I am not an engineer, but it seems to me that ceteris paribus, the more "springy" you make a building, the better it will handle dynamic loads (within limits, of course!), but it will then do worse with static loads. You can drop a 100 lb weight onto a trampoline with no problem, but the trampoline will sag under the static load.

Cover the trampoline frame with a sheet of glass thick enough to support a 100 lb weight, place the weight on it, and every thing is O.K. But if you drop the weight onto the glass, all hell breaks loose.