It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Merely replacing existing windows with blast-resistant ones anchored to the existing brick infill would not be a workable solution. The newer windows would direct blast pressures to the window support connections at the infill. The tensile and shear loads would overwhelm the existing infill walls and allow the panes and frames to separate from the walls as potential missiles harmful to personnel working in the building. A typical bay with window is illustrated below.
The resulting general design solution called for erecting structural reinforcements around the windows, anchoring at the top and bottom to structural concrete floor slabs and not the non-structural brick infill walls. This general solution also accepts blast forces from the walls themselves and transfers both window and wall loads into the horizontal slab diaphragms.
This solution has a tubular frame for each windowed wall panel, consisting of two vertical tubes (HSS 6 ï¿½ 6 ï¿½ 0.25 on floors two through four, and HSS 8 ï¿½ 8 ï¿½ 0.1875 on the first floor) horizontally braced with tubes (HSS 4 ï¿½ 4 ï¿½ 0.375) welded at each window's head and sill. (See the above picture for a rendering of the structural frame at a typical second floor window.) The frame becomes the structural support for the blast-resistant windows, with the vertical tubes giving new blast protection to the infill walls.
To make the solution work, HSMM designed a practical floor-ceiling connection scheme for the vertical tubes. The tubes must withstand large deflections to perform their intended function of absorbing blast loads. Large deflections, however, with their inherent shear, create significant tensile force on connecting hardware in a blast situation. This condition eliminated the more direct "top/bottom" approach of connecting the vertical tubes to the concrete slab above and below with expansion anchors.
With the stringent design criteria minimizing intrusion into tenant space, the solution had to work in the narrow space between the tubes' interior face and the interior face of the brick wall, a matter of only a few inches. The answer was to weld the tubes to long, narrow plates running along the floor and ceiling. These plates connect to their counterparts on floors above and below with through-bolts, using 3/4"-diameter A36 threaded rods. To maintain good connection to the slab for constructibility and to compensate for variations in tube length, the vertical tubes are also welded to opposed double gusset plates, which in turn are welded to the floor/ceiling plates. This solution connects the window frames from floor to floor. This design directs dynamic horizontal blast forces through the flexible tubes into the floor diaphragms. This approach was uniformly applied to the window panels on the second, third and fourth floors.
The first and fifth floors, due to the existing construction mentioned earlier, posed special problems. Because the first floor is slab on grade, connecting the tubes to the floor slab by through-bolting would not work. And since anchor bolts could not take the calculated tensile and shear forces, a different approach was required. A core-drilled hole in the slab on grade accommodates the tube bottom so the tube will bear horizontally against the floor through a bearing plate. After inserting the greased end of the tubes, the holes are grouted to create a bearing surface and protect the capped tubes' ends from soil moisture corrosion.
The first floor ceiling configuration created a separate connection challenge. The spandrel beam from the second floor protrudes approximately 4" (102 mm) from the interior wall for about 17" (432 mm) down from the ceiling, forcing the vertical tubes several inches away from the infill wall and window frames. The resulting gap below the spandrel had to be "closed" to maintain structural integrity by using a dry-pack, non-shrink grout and by welding a 3" wide (76 mm) spacer tube (HSS 6 ï¿½ 3 ï¿½ 0.3125) along the length of the HSS 8 ï¿½ 8 tube face. The tubes' top connection used the same through-bolt scheme as the other floors, aligning with the bottom plates on the floor above.
Now what is presented here in its short form has got to be more than satisfactory to any reasonably clear headed thinker to deduce on their own that in fact there was "no Boeing 757, 767, 737, 707 or 747 near, on or about the general premises of the Pentagon on September 11th 2001.
Originally posted by donttaserme
maybe this is more to your liking .. harrd to chew isnt it .. one day you might just open your eyes
oh yea one more thing .. if all this isnt "evidence" enough for the non believers then where is the proof that a plane hit it at all ? ive never seen a video or a picture or anything except what "they" say happened ..I never seen a plane hit it.. you never seen a plane hit it. so tell me why do you think it was a plane at all?
[edit on 03/06/09 by donttaserme]
posted by s4dreamlnd93
Have you seen what JP5 does to aluminum when it is on fire? The black smoke shows that there is a significant amount of fuel being burnt and is very much a sure sign of class bravo fire.
Also if you re-watch the first 1 1/2 minutes of the footage you can see metallic debris all over the grass.
Originally posted by benoni
Thats a great photo you got there s4....
What do you propose happened then when the plane hit those cable spools...they sure dont look too plane impacted to me.....the ones in front of your wing impact point...??
Same goes for the panes of airplane-proof glass which miraculously stood firm during The Attack .....you know, the ones above the wings, those pesky wabbit wings which vapourised upon impact with the spools....you can see the windows are still intact due to the fire retardant foam sprayed all over them...and the spools look untouched to me...
And dont forget....that jet fuel was soooo hot it melted all that steel at WTC1 and 2....
So does that mean that if WTC1 and 2 were made of Pentacon Grade Glass beams rather than steel, they would still be standing?
I can understand your confusion boys.....
I think theres a couple of people watching this thread who are masquerading as comedians .......if it wasnt so tragic, there comments would be laughable...
thanks again for a great photo mate....as you mentioned, you dont see that pic around much....
same goes for thedmans "the whole plane is inside the building via a hole less than 20ft wide" theory....
[edit on 12-3-2009 by benoni]
Originally posted by donttaserme
the hole was 16 feet in diameter.
the 757 is 156 feet long
44 feet high
124 foot wing span
you do the math
Of course people with brains now know for a fact that the real decoy aircraft flew Over the Naval Annex and North of the Cirgo gas station and above the light poles and overhead highway sign, and went nowhere near the staged downed light poles and taxicab and burning generator trailer. Nor did any air frame impact the Pentagon.
Originally posted by benoni
Closely followed by this one...ignore the circles....this is the last inner ring's damage.....how a plane did it though is beyond any persons rationale understand....only an idiot would believe a plane did this, let alone argue the point...!!
Note the complete absence of anything even remotely resembling a planeon 13-3-2009 by benoni]
[edit on 13-3-2009 by benoni]