Torus shape variations and cuttings.

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Comment by Ángel Linares on August 10, 2012 at 6:30pm: xD...man, wait, I'm not structure teacher. :P This is not a structures forum neither, and I'm not here to talk about how to calculate wind loads over free formed roofs ;).

But, normally, when you have a free-form surface is better to make some CFD analysis if you want to be accurate. The code only gives you simple examples to solve simple problems (double pitch roofs, cylinders, etc...), if you want to go further you need more than the code examples ;) I'm sending to you a spreadsheet capture in PDF with the calculus of win over a variable section skyscraper. With that email I finish the structure lesson ;). Be kind, I'm sure than there in Serbia must be someone else who could help you with this.

You are welcome ;)

Comment by djordje on August 10, 2012 at 6:12pm: Actually I would be grateful if you could help me out with the calculation of the wind load according to EC. I got the EN 1991-1-4 standard (I think it is the newest one - from 2002.) and except for the domes there is no specific category for free formed roofs.

I started reading the EN 1991-1-4, parallel with this example of a two pitched roof wind load calculation. The problem emerged on the very start in the section EN 1991-1-4 4.2 where basic wind velocity values were calculated. In upper example they took 26 m/s for Aachen, Germany. Whereas European wind map shows only 5-11.5 m/s - differing for different types of terrain in that area.

Maybe you can send me some of your examples of wind value calculations?

If you think it is more appropriate to reply on this by email, than here is mine: issworld2000 [at] yahoo [dot] com.

Muchas gracias !

Comment by Ángel Linares on August 10, 2012 at 5:35pm: In this simplified model we take 1KN/m2 and applied only over to zones of maximum exposure index. I have some pictures showing these areas shaded, if you want I could sent to you ;). Our experience calculating wind loads with eurocode tells us that considering location an the height of the structure, 1KN/m2 was a really safe-side choose in this model.

In other skyscraper models we made a more "scientific" calculation because of the higher exposure index (and location data), the brace produced in the base, and the natural period of the global structure (quite higher than this stadium) ;)

Hope this answer your questions ;) You are a really curious guy :P

Comment by djordje on August 10, 2012 at 4:57pm: I see. Thank you for the reply Angel.

Can you tell what value for the wind load did you take ?

Comment by Ángel Linares on August 10, 2012 at 4:35pm: That analysis are useful to identify compression and traction areas, because the frame mesh that you need to design before must take care about that. It's faster to analyse meshes that lot of frames. That's because we made this meshes models and the Kangaroo model before the final frame model.

Comment by Ángel Linares on August 10, 2012 at 4:29pm: This is a fem analysis showing deformation, and "forces" inside surface in the two main directions (f11 and f22).

Alessandro was my partner in this assignment. We developed together the geometry, the FE analysis and the conclusions and optimizations. That is because he is in credits. I made this chart today to show you some of the structural design process. We put this images in a really long document arguing about the design and process.

Hehehe, the thing about Prometheus was only a joke ;)

Comment by djordje on August 10, 2012 at 4:10pm: I believe you it was before Prometheus :)

Thank you for the image Angel. Looks great !!!

What we see here is result of a FEM deformation analysis in sap2000? Alessandro Gubinelli did this?

Comment by Ángel Linares on August 10, 2012 at 10:39am: I know, I know lower cuttings looks pretty similar to Alien Engineers ship... damn it! I swear it was before Prometheus...hehehe :P