The 9/11 Forum

by **Heiwa** » Wed Mar 11, 2009 7:54 pm

Benson, you have to read what I say. In the example given - load transfer via spandrels - the hat truss was simply ignored. But I suggest that it can be considered. Yes, some load of a wall that is hanging on the hat truss will then be transmitted to the core, while the rest of the load is transmitted to the adjacent walls via the spandrels.

What does it mean? The load in question - the one carried by the south wall - is 12.5% of the total load that the upper part C applies on part A. I suggest - ignoring the hat truss - that 6.25% is transmitted to the east and west walls, resp., via the spandrels when you remove all columns locally in the south wall. 0% via the hat truss.

We can consider the hat truss. Say it transmits 4.5% to the core, then only 4% is transmitted to the east and west walls, resp., via the spandrels.

But let's face it. The hat truss was not designed for walls to hang on!

Reason for the hat truss was that you could not just bolt the roof to the walls like a floor. So they made the roof a little more sturdy = hat truss. Then they could fix the mast to it and avoid wires to the walls to support the mast.

How are you getting along with your 2-D model? With UUU you can include a hat truss + mast also.

by **Major_Tom** » Mon May 04, 2009 1:50 am

OWE, check this out.

http://www.youtube.com/watch?v=O4QgJuHqwFY&feature=channel_page

by **OneWhiteEye** » Mon May 04, 2009 4:55 am

Major_Tom wrote:OWE, check this out.

http://www.youtube.com/watch?v=O4QgJuHqwFY&feature=channel_page

The first segment, all I can say is WOW. I wish I'd seen this a long time ago. Further inspection is necessary, frame by frame, with enhancement.

Thanks for finding that and putting it up.

by **Major_Tom** » Fri May 08, 2009 3:22 am

OWE, I have no way of downloading the first 15 seconds of this video. If you have this on your computer, is there any way you could make it available to others (me) via e-mail or something else?

Just to show you how poorly this hinging is understood, Mangoose's couple of JREF posts from over 14 months ago are still cited as evidence of some significant cubic "tilt" the upper block supposedly underwent.

It's an open book.

by **OneWhiteEye** » Sat May 09, 2009 10:17 pm

Major_Tom wrote:If you have this on your computer, is there any way you could make it available to others (me) via e-mail or something else?

Sent you a PM. I don't trust this board to deliver messages, since four of them are still sitting in my outbox, including the one to you.

Just to show you how poorly this hinging is understood, Mangoose's couple of JREF posts from over 14 months ago are still cited as evidence of some significant cubic "tilt" the upper block supposedly underwent.

It's an open book.

The view from the east side gives one impression, this gives another. I wish I had the original footage!!!!!!

by **Major_Tom** » Thu May 14, 2009 1:39 am

In a different thread HB identified an excellent physical tool to understand the nature of tubular structures:

If you want to under stand the buckling of the tube structure, press lightly on the side of a beer can while standing on it.

Same with crushing a can down on itself using a lever. I was watching a family member crushing cans this way and noticed they always put a slight dent in the side of the can before pulling the lever. I asked why and they said it is not easy to crush a can this way but all that changes by adding the slightest dent.

A beer can show you everything I tried to describe here:

How Do You Break a Tubular Structure?

Semi-flexibleTube-like structures with square cross-sections bend and break according to the following sequence:

Case 1: Starts to kink in a corner:

1) Kink forms in corner

2) 2 progressive creases form across the faces adjacent to the kink

3) bending of tube (what we call "tilting")

A crease (or seam) is a collective somewht linear progressive deformation of groups of columns

The displacement of surface of the crease or kink is always normal to the local surface of the tube

Kinks and creases will be displaced inwards.

Case 2: Starts to crease along one side

1) Some type of deformation is witnesses along one face (a crease,"dimple" or lean or other?)

2) This deformation progresses into an inward crease

3) crease reaches adjacent corners, corners kink

4) Entire side reaches critical creasing and rips, effectively severing top wall from bottom

5) Tube begins to bend as either creases or progressing failure and crushing is seen to progress down the sides of the tube

6) Tube continues to bend because the only face of the tube left intact, the face opposite the bend, bends. Note that this is the only face of the four that fails by bending, not creasing.

The WTC1, 2 perimeters are in every way semi-flexible tubular structures. They must either kink, crease or progressively deform in some way before "snapping" or ripping in two parts.

Semi-flexible tubular structures cannot just "snap" along a horizontal line and separate into top and bottom without considerable struggle: progressing deformation, collective creasing or other very noticable struggle before failure.

They must be seen to deform significantly before they can separate into two parts: top and bottom.

The initial perimeter failure of WTC1 is totally different than how a meshed tubular structure can be expected to fail.

It failed way too easily.

If you don't want to read all this, just play with your beer can after you finish the next one and you can see all the properties at work.

The tube is an extremely strong structure until a crease, kink or dent forms in it. At that time my own mother can crush it, but before the first dent she won't have a chance.

The WTC1 west wall just splits in two with no initial visible crease. This is unphysical. (And then the top kicks out over the bottom. This, too, is unphysical.)

by **David B. Benson** » Sat May 16, 2009 12:37 am

Major_Tom wrote:The WTC1 west wall just splits in two with no initial visible crease. This is unphysical.

No, it just means you cannot see the crease (probably on the inside).

(And then the top kicks out over the bottom. This, too, is unphysical.)

This is from the story 97 windows down, yes? If so, it is precisely what I would expect.

by **Major_Tom** » Mon May 18, 2009 3:36 am

You haven't followed much of what I've been writing. You may want to try to understand it before offering an opinion.

For many posts now I haven't been able to decipher any notable useful infomation in any of your responses.

I post here to offer and receive useful information from others. Your comments on some of the threads in which I have been trying to discover and offer new information have been troll-like.

If you have anything useful to offer, please do. But the world is already filled with superficial aswers to complex questions, so why offer more one-liners?

Best to think before posting.

by **David B. Benson** » Mon May 18, 2009 9:48 pm

Major_Tom wrote:You haven't followed much of what I've been writing.

False.

You may want to try to understand it before offering an opinion.

I do.

Your comments on some of the threads in which I have been trying to discover and offer new information have been troll-like.

False. "In Internet slang, a troll is someone who posts controversial, inflammatory, irrelevant or off-topic messages in an online community, such as an online discussion forum or chat room, with the primary intent of provoking other users into an emotional response[1] or to generally disrupt normal on-topic discussion." from
http://en.wikipedia.org/wiki/Internet_troll

If you have anything useful to offer, please do.

I always try to do so. For example, at the time the west wall broke, there was already at least 215 MJ available to do the breaking.

But the world is already filled with superficial aswers to complex questions, so why offer more one-liners?

Often one line is enough for the educated. If not, feel free to ask.

Best to think before posting.

Best you follow your own advice.

by **Major_Tom** » Fri Jun 19, 2009 5:59 pm

False. "In Internet slang, a troll is someone who posts controversial, inflammatory, irrelevant or off-topic messages in an online community, such as an online discussion forum or chat room, with the primary intent of provoking other users into an emotional response[1] or to generally disrupt normal on-topic discussion."

Exactly.

I'd like to just ignore the last post and move on.

In a different thread Femr2 posted the best quality clip I've seen on the failure of the west wall:

http://www.youtube.com/watch?v=RN1Fq090sBA

We can see the S to N ejection pattern. It moves so rapidly across the W face that it is hard to detect unless we use the high res version and play it at slow motion as Femr does.

If we think of a hinge as a competition between a failed side of the building (south) and a side that has not yet failed, we can see that the north and west perimeters provided very little detectable resistance to failure.

The entire west perimeter sheet provided practically no resistance to failure along a single horizontal line.

On another thread I showed that during this initial failure along the west perimeter the top portion quickly detached from the building, fell outwards and over the bottom portion and went into freefall as 2 or 3 giant interconnected sheets about 8 floors high.

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=92&MMN_position=224:224

Femr2 provided a good amimation of the upper block west perimeter falling

I then showed that images of the largest piece of the freefalling upper block perimeter appeared to be cut in a straight horizontal line along it's bottom edge just under a spandrel plate, totally unbuckled.

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=98&MMN_position=232:232

Concerning such straight lateral breakage of many perimeter columns along the bottom of a spandrel plate, I showed a second example of the whole NE corner assembly

1) popping away from the building at the earliest moments of collapse initiation as a large sheet
2) being totally unbuckled
3) being from the "upper block"

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=91&MMN_position=223:223

In addition I showed that the whole west perimeter below floor 94 peeled away from the building as a single interconnected sheet

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=97&MMN_position=231:231

If you combine all the ideas linked above, we can see a rough model for the complete dynamics of the WTC1 W perimeter.

This complex action is what people call a "hinge".

by **femr2** » Sat Jun 20, 2009 6:33 pm

Major_Tom wrote:Failure of the west wall:
http://www.youtube.com/watch?v=RN1Fq090sBA
We can see the S to N ejection pattern. It moves so rapidly across the W face that it is hard to detect unless we use the high res version and play it at slow motion

For those who don't 'do' video, here's a thumbnail view of the S to N ejection pattern:

Add: It should be noted that the North Face is already descending before the S to N ejections reach the NW corner. Easier to see by watching the full resolution video, but I can add another thumbnail clip here if necessary.

by **David B. Benson** » Sat Jun 20, 2009 7:24 pm

Major_Tom --- Good summary, thanks.

femr2 --- Thank you.

by **femr2** » Thu Jun 25, 2009 2:52 pm

OneWhiteEye wrote:
Major_Tom wrote:OWE, check this out.

http://www.youtube.com/watch?v=O4QgJuHqwFY&feature=channel_page

The first segment, all I can say is WOW. I wish I'd seen this a long time ago. Further inspection is necessary, frame by frame, with enhancement.

Thanks for finding that and putting it up.

Not sure if this version is any better in terms of quality, but I've cleaned it as much as I can...
http://www.youtube.com/watch?v=mUaT09OSx_0

by **femr2** » Thu Jul 02, 2009 9:12 pm

Have found another view of the 'tilt' of the cap of WTC 1, and although difficult to see, my impression is that, after slight initial tilting of both antenna and cap, that the antenna tilts independently of the tilt of the cap itself.

YT HD Video
Indeed, if you track the movement of the LHS of the roof-line and watch the movement of the top of the antenna, they appear to separate quite early-on.

Correlating to movement of the antenna on this video with movement of the actual NW corner of the cap would confirm this behaviour, and I shall do the leg-work asap.

In the meantime, anyone want to hazard a guess on explaining how the antenna could become separated so early-on, and what effect that would have upon the rigidity of the rest of the cap. (I assume that it would have a significant effect on the hat truss, and imply a much earlier break-up of the cap than some folk suggest.)

by **David B. Benson** » Fri Jul 03, 2009 3:51 am

femr2 wrote:... my impression is that, after slight initial tilting of both antenna and cap, that the antenna tilts independently of the tilt of the cap itself.

Unlikely. On PhysOrgForum shagster posted about using some video to track one of the antenna mast stay wires, stating that it remained rigid so long as visable.

I suggest that the camera angle might be misleading you.

The 9/11 Forum

Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

Re: Did WTC1 "hinge" like WTC2?

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