That chess analogy is a good one. I play reasonable club level chess. I've even won a couple of prizes in local competitions. But a Grandmaster could thrash me with his eyes closed and I wouldn't even know what happened. We're not even playing the same game. I played in a simultaneous display against an International Master (a level below a GM) and he crushed me. I hadn't got a clue my position was so bad until it suddenly collapsed, rather like....The World Trade centre.
It's the same for all incompetents. We're full of ourselves, like Heiwa and co, and think we're holding our own, maybe even impressing a few people, all the while unaware of what total arses we're making of ourselves.
Howdy Oscar,
I would respectfully take exception to this analogy.
In chess, if you make a lousy move, you may be able recover and beat your opponent.. Because a lot of your effectiveness comes from parallel stength (multiple pieces). And because your opponent might make a mistake.
Mother Nature is an International Grand Master. (Or maybe, "Deep Blue".) She NEVER makes a mistake. And she's a cast iron witch.
Engineering analysis (and their conclusions) are absolutely intolerant of out-and-out blunders. They are much more like a linear chains, limited by their weakest links.
Heiwa's nonsense is a classic example.
A bunch of the individual things that he says are right. But each has multiple errors buried in the details. This sloppiness results in a bunch of useless chains.
Here's a perfect example:
The World According to Heiwa:
The part A columns, undamaged, between floors 96-97 ...
.
Just one little phrase that you might gloss over as a "reasonable approximation". Nothing could be further from the truth.
I've pointed this out to him a dozen times. Dozens of others have as well.
With his oft-repeated statement "part A columns, undamged" and in his silly graphics on his home page, this is what he portrays the interface between the floors above & below floor 98 immediately after the initiation of global failure:
[imgw=211]http://www.internationalskeptics.com/forums/picture.php?albumid=176&pictureid=1314[/imgw]
Fig 1. Heiwa's Fantasy Portrayal of the Interface between Floor 99 & Floor 97
The above erroneous presentation applies to anyone who models the columns as one story high. I've seen Tony Szamboti express it in the same terms.
.
Below is what the external columns of the lower block looks like in reality, IF just ONE column assembly "popped". It's a Snaggletooth. In this 3D graphic, I've shown the outer columns, and the damaged floors of Floors 97 and below.
[imgw=211]http://www.internationalskeptics.com/forums/picture.php?albumid=176&pictureid=1313[/imgw]
Fig. 2: Real configuration of lower columns after failure initiation
On the 97th floor, ONLY ONE out of every 18 cross trusses will remain intact and supported at both the peripheral and core columns, simply as a result of popping ONE column assembly all the way around the building.
I've removed the floors where the a peripheral or core columns have been popped. In reality, the open spaces would be spanned by the rebar embedded in the concrete. But the floors (especially on Floor 97) would have virtually zero ability to support any load.
Note that this is the state of the 97th & 96th floors BEFORE the upper block strikes the floor.
____
In order to show what the impact of this stagger has on the stability of the top end of the remaining columns, I've tallied the constraints that the columns had before & after the collapse.
In the graphic below, I've shown the missing columns above and below the 98th floor with black dots.
[imgw=213]http://www.internationalskeptics.com/forums/picture.php?albumid=176&pictureid=1315[/imgw]
Fig. 3. Missing connections
In the graphic below, I've shown the constraints that are remaining for the top most columns. In this graphic, all the linear connections are shown. In a fully constrained point, there would be a total of 6 connections (2 each in x, y & z axes).
In addition, I've tallied the moment constraints. In a completely constrained point, there would be 3 moment constraints, one around each axis.
[imgw=493]http://www.internationalskeptics.com/forums/picture.php?albumid=176&pictureid=1316[/imgw]
Fig. 4. Column constraints
Prior to collapse, all the column-to-truss connections had 5 linear and 3 moment constraints. The top & bottom splice had 2 linear and 3 moment constraints.
After the start of collapse, the top of the column has lost all constraints. The other locations have variable constraints remaining, as listed.
Note that this constraints table tallies all the constraints for 9 side-by-side columns. All the missing columns have lost all constraints, of course.
The end result of losing all of these constraints is that the columns are far, far less capable of supporting loads than they were prior to the collapse initiation.
In other words, Heiwa's reference to "Part A columns, undamaged, between Floors 97 and 99" is utter, unmitigated nonsense.
___
Probability of a "One Column Failure Mode".
Finally, note that the "one popped assembly" is not the most probable failure. A 3 point kink, with each knuckle at a column splice joint is. A perfect example of this failure mode can be seen in this video.
http://www.youtube.com/watch?v=xGAofwkAOlo
Watch the left 1/3rd of the building at 2:11 seconds as the collapse begins. There is a "slab" of 6 assemblies wide by 2 assemblies high group (36 total columns that span 8 full stories) that all lets go at once. The left 9 columns in this group seems to buckle inward in the middle, while the right 9 columns buckles outward in the middle.
___
Again, in engineering, the devil IS in the details. All of the above comes out of just one of Heiwa's sloppy phrases. Conclusions that follow from such sloppy assumptions are junk.
Tom