Tower 1&2 Exterior box columns

Could somebody please tell me how thick was the steel which made up the exterior box columns.

Google is your friend ;-)

911research.wtc7.net...

There were different thicknesses depending on the height. Happy reading.

Thanks.

Column plate thickness varied from 1/4 inch to 5/8 inch in the impact zone of WTC 1 for floors 89-101, and from 1/4 inch to 13/16 inch in the impact zone of WTC 2 for floors 77-87.

14x14 inch exterior columns sound very solid but whe you realise they are only 1/4 inch thick it makes you wonder how strong they actually were.

My problem is this, it appears to be the case that the exterior columns should be the thickest nearer the bottom, i assume this picture is near the bottom as it looks like it is still stnding.
www.photolibrary.fema.gov...

Column W51 (nice of them to number for us) the column with the big hole in it, has to have the thinest veneer of steel i have ever witnessed.

well the thickness is relative. It's the actual beams that held everything up. The steel veneers you see were mostly for just holding the columns together, not for load bearing.

It's the actual beams that held everything up.

Liken the tower structure to a chair, back legs are the core columns, front legs are the exterior columns, the seat area would be the floor truss and concrete floor. Stand on the seat and get your friend to cut away the front legs, after you pick yourself up from the floor tell me those legs were not load bearing.

The floor truss spand from exterior columns to the core columns, the weight (both live and dead) is equally distributed between both. That makes them (external columns) load-bearing.

So what beams is it you mention that "held everything up"?

Originally posted by Rotator
Liken the tower structure to a chair, back legs are the core columns, front legs are the exterior columns, the seat area would be the floor truss and concrete floor. Stand on the seat and get your friend to cut away the front legs, after you pick yourself up from the floor tell me those legs were not load bearing.

You cut that chair exactly in half when you do that. The core held more than half of the gravity loads. The trusses wouldn't have anything to latch onto if perimeter columns started falling away, but it wouldn't lead to a global collapse either, or anything but a local collapse, just like what happened because of the impacts knocking floors and perimeter columns out. The trusses wouldn't come completely lose and free-fall downwards like dominoes either. Not saying you suggested any of that.

The floor truss spand from exterior columns to the core columns, the weight (both live and dead) is equally distributed between both.

Not equally. Where do you get equally from?


Btw,



1st one is a cross-section, insulation, window connections and all, 2nd one is just the column as they were near at the top floors, the 3rd one is from the lower floors. Support got a lot smaller in general near the top because they still had the same number of columns but the loads they needed to carry were substantially less. So they reduced column size and saved further load farther down. Notice that back panel that you saw peeled away is small even for the lower columns.

[edit on 20-3-2007 by bsbray11]

Not equally. Where do you get equally from?

I got equally from thinking about the load (dead) of the truss and concrete floor. I assume that is the load you mention when you say

Support got a lot smaller in general near the top because they still had the same number of columns but the loads they needed to carry were substantially less.

Unless you ment the live load was less the further up the building because less people worked on the higher floors and they had less equipment than those on the lower floors. I'm sure you never ment that.
Hope you caught that Sensfan, load on the columns.

Bsbray...The image you show showing the cross section collumn is wrong/fake. It clearly contradicts the FEMA photographic evidence www.photolibrary.fema.gov...

Would there happen to be a column section detail from the Nist report?

Is it me or the breaking points of the floors supports are rougly all the same?
(on the first pic)

Maybe they were like that in the first place....but then again maybe not..

Originally posted by Rotator
I got equally from thinking about the load (dead) of the truss and concrete floor. I assume that is the load you mention when you say

Support got a lot smaller in general near the top because they still had the same number of columns but the loads they needed to carry were substantially less.

The floor loads you're thinking about are only a portion of the total loads, and I would think they'd be a relatively small portion. The core structure looks to me as though its total dead and live loads were the bigger loads that the tower took (look at construction pics to get an idea of how the dead loads compare; the core was made for heavier floor loads within it, too, for live loads). The floors outside of the core were relatively clear and would have just had office type stuff on them. The core had a lot more going on.

Unless you ment the live load was less the further up the building because less people worked on the higher floors and they had less equipment than those on the lower floors. I'm sure you never ment that.

The dead load, yes, of the whole building. The bottom floors' columns have ~110 stories stacked on top of them. The uppermost floors have 3 or 4 floors stacked on top of them.

Bsbray...The image you show showing the cross section collumn is wrong/fake.

It's from before 9/11.

It clearly contradicts the FEMA photographic evidence www.photolibrary.fema.gov...

How does that not match up? I see no difference at all.

[edit on 20-3-2007 by bsbray11]

I am not concerned with the load within the core, anything between the outer core columns and the exterior columns includes

dead load ...Trusses/concrete/windows/ventilation ducting/ceiling/raised access flooring?
Live load... machinery/furniture/office equipment/People/demountable partitions ect

Both dead/live combine to make the total load which was carried by both interior and exterior columns, not unless we got some quantum truss that transfers the load only to the interior columns.

No need to bring up inside the core again in this thread.

How does that not match up? I see no difference at all.

Well column w51, we are looking from what would be inside the building looking out. The thin veneer of steel that makes up the inner face of the column, it sits between the side walls, your sectional drawing says it should project past the sidewalls.

You also mention about the sectional drawing

1st one is a cross-section, insulation, window connections and all, 2nd one is just the column as they were near at the top floors, the 3rd one is from the lower floors.

Insulation? The numbers on the drawing are there for a reason.

Are you attempting to hide something by not providing the index for the numbers?

Never mind here they are for those interested www.caddigest.com...

WOW fire risistant plaster has been formed around the thin veneer of steel to form the box section we all know.

I will leave it at that for the time being.

What are you trying to show by ignoring the core and isolating the loads between it and the perimeter? Is there a point?

That back panel is going to be thin no matter what part of the building it was taken from, so I don't get your point there, either. It doesn't represent the thickness of every side of the perimeter columns.

If we are going to talk loads. We have to incorporate all of the loads. That includes wind load, earthquake load & roof load (including snow and rain loads). Those loads are also taken into account when designing a building.