bill smith
Philosopher
- Joined
- Feb 14, 2009
- Messages
- 8,408
I thought that the hat truss had the vital function of tying all the elements together at the top of the building ? Redistributing loads between the core and the perimeter columns and so on ? The antenna appears to hhave been an afterhought given that iit was not added until years after the buiding was complete. So the antenna design and attachment would have had to be tailored to work with and around an already in-place component.Something like that, maybe. The photo on the page I linked is most likely a picture of that assembly. They wouldn't need to run right through the hat truss; the job of the hat truss was to support the antenna, and if the antenna had connected directly to the core then the hat truss would have been redundant.
The connection shown in the photograph looks more than adequate. The majority of the forces would have been torque rather than lateral force, and the guy wires were there to handle that.
There's a 1000 foot radio mast not far from where I live, held up by fifteen bracing wires. The connection at the base is remarkably small, in fact it looks more like a pivot than a solid connection. The WTC1 antenna connection looks a good deal more solid to me.
Dave
To make the antenna safe the only logical thing to do would be to attach it to the core so that when he wind acted on the building and caused it to sway in one direction at a particular force that the antenna, as an extension of the core would go with it and suffer the minimum possible stress. To be welded directly to the core means it had to pass through the hat truss. In any case attaching directly only to the hat truss could have caused interference in it's normal and vital function.
In that antenna you mention ...the 1,000 foot one. how far are the furtthest guy ropes fixed in the ground away from the tower ? It must be quite a long way for such a tall structure to get the desired angle. In WTC1 the furthest away that such cables could be fixed at 'ground' level was about 100 feet whch is not a lot.Obviously support cables cannot be too close to vertical for maximum efficiency.
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