Wind load on a mast according to ANSI/TIA

[AF-thyman]

Hello!

I'm having a problem with my model of a mast, see attached. I want to verify it according to the american code ANSI/TIA (I'm from Europe so this is a bit unfamiliar for me).

I found this document while trying to set it all up, and I've tried to adapt my model accordingly: Wind Loads - Masts / Towers (TIA/EIA-222-F code). Focusing maninly on the note:

"Tower loads are available only for 3D bar structures: frame 3D and truss 3D. The base of the structure must be an equilateral triangle or rectangle. For the shape to be recognized, assign supports to the nodes located at the apexes of the structure base. These must be the only supports defined in the structure.."

However, I am not able to select "Wind on Towers" since it's being ghosted for me. I'm using RSA 2014 with a 3D truss structure model. The tower has a hexagonal shape at the top which converts into a triangular shape by the base (in accordance with the above quoted note). I have also changed both the global preferences and job preferences to american units and design codes.

Any help is much appreciated.

/Regards Marcus

[rioja]

Hi Marcus

You should take care about the model because the geometry is not the best (triangular base + hexagonal tower)

The vertical forces must "bend" to reach the supports

If you want to enable the "wind on towers" , then go to :

Tools / Customize / Customize Menu (opens a window) / Loads / Wind and Snow / 

click on + click on the red Dot and it turns green

OK

If you use the newer version of ARSAP 2015

go to 

Loads / Wind loads simulation / Simulate wind loads...

Apply all the directions you consider necessary if you don't feel sure which one, apply all

Choose the wind velocity according to TIA 2.3.1 ... 2.3.4

take care about the ICE load and the increment of section in presence of ice.

Place also the antennas in its final position

[As an approach to the generated load you can calculate

  S   Fx = S bi*li*q  the same for y

To make easy use a section like CARR100, then you can change the section and regenerate the wind loads ]

Regards

Marcelo

[AF-thyman · Accepted solution]

Hello Marcelo!

Thank you for a quick and extensive answer. The option that you referred to was however already set to "on" in my project.

 Regarding the shape of the tower, what is visible is only the top, the triangluar will continue further, as to why this hexagonal shape was chosen, I don't really know but it was a design criterion.

On the othe hand, I managed, to locate the problem. It seemed that I had to add the TIA/EIA wind load to used design codes under job preferences.

Now I just have to get familiarized with the American Standards, but that's an enitrely different problem!

Once again, thanks for your time and expertise!

/Regards, Marcus