why the wtc towers fell - on pbs

huangyhg

why the wtc towers fell - on pbs
for u.s. (and perhaps some canadian) members of eng-tipsfff"> members: here is an interesting program on the collapse of the world trade center towers.  it is based on the asce investigation and report.  it's a good place to direct your curious non-engineer friends who want to understand why the towers fell.  here's the link for additional information as well as the press release i received by email:
is that a re-run?  
i'm pretty sure it is a re-run; but i'm not certain -
we have had several documentaries in the uk covering this subject. no doubt some of the material used in the program is from the same source. in the documentary over here they had an interview with mr robertson, the structural engineer who lead the design team, and i really felt for him. he seemed to be devestated at the fact that he couldnt forsee such a terrible act - who could!
as a structural engineer myself, i consider the solution for the buildings to have been an elegant and clever design and the engineer did absolutely nothing wrong.
perhaps when the program has aired focht3 and others could post with a summary of the findings and we could discuss the facts and compare with the documentaries others have seen.
regards
on the day i saw the news i had this idea that binadin's plane killed less than a hundred with the initial plane impact.  it was the engineering design that kill the thousands.
i fully agree with some of the posters here that it was not in the scope of design of the towers to include terrorism provision at that time.  the structural engineer is therefore not to blame.  we now live in a world different to the designer of the twin tower and we have to think of the terrorist risks.
i have been puzzled by only one feature on the collapse of the twin tower.  are the terrorists really that clever or it was down to pure luck?  they had to have to access to world experts on structural engineering, tall buildings design, material science, aeroplane design, daynamics and combustion engineering to pull it off as they did.  i know binadin is just a huge civil engineering contractor in saudi but i am not convinced he had the necessary know how.  seems to me it was binadin's own mistake because of his lack of engineering appreciation to understand the consequence.  that action led to thousands of his followers died and his base uprooted in afganstan.  he can no longer openly exists anywhere in this world and his religion suffers a bad name for generations to come.  
there was an earlier discussion on the collapse of the towers in one of the eng-tips fora... i've tried searching for it without avail... if anyone can dig up the thread, it would be appreciated...
i can't quote the source, but i recall hearing that obl (osama bin laden) was surprised that the towers fell.  he had not anticipated that outcome; many others (myself included) were surprised as well.  i think it was the prolonged heat from the fuel that was the unexpected factor.
i suspect we all have a much healthier respect for the potential consequences of fire, particularly where a large pool of accelerant is involved -
focht3:
it was easy for obl or any or his guys to claim credits but any educated person will know his head would be on the line thereafter with the full might of the world after his ass.  can anybody be stupid enough to sign his own death warrant by risking the hatred of the whole world?  
i was surprised by the collapse too.  i think it would be right to say if the planes had very little or no fuel left then the two towers should have stood because the fire risk would be low.
the progressive collapse within the central core, pulling the outer shell neatly to the inner is unseen and unheard before the disaster.  i doubt if any structural engineer has set out to engineer a collapse intentionally, for all intents and purposes, within the footprint of such a tall building.
englishmuffinfff">:
we are both right - and wrong...
i found the following link to npr's web site (after a google search for 'osama world trade center collapse videotape'):
the pbs documentary is a re-broadcast.  the structural engineers that performed the post-mortem concluded that the high heat from the fuel load weakened the structure.
in any case, the collapse was un-anticipated, since the structure was designed to handle a 707 impact with margin.  had obl thought that the towers could be brought down and or thought through the amount of potential damage, he would have designed for a lower strike point on the tower, i.e., down to possibly the 40th floor.  this would have been above the capabilities of any ground-based fire-fighting equipment, while maximizing the possibility of causing the towers to weaken and fall sideways, which would have increased the potential damage.
it's more likely that obl thought that the towers would  pancake down to the impact site and no further, which would have left two damaged towers as a constant reminder of his power.  it would have taken much more than 8 months to clean up and would have taken many more months to repair or rebuild.  i suspect that a full collapse was undesirable, since that would have meant a relatively quick clean up and no obvious reminder of his deed in the skyline.
ttfn