[REQUEST] Circus Show Tent Design Forten Oasys GSA Fabric Tensile Structure

[LiviuM]

Dear reader,

Please share documents and if possible a model of a large tent.
A model in Forten2000 or/and Oasys GSA will be highly appreciated and rewarded.
Also design notes or drawings.

Here are some samples of what I'm requesting:

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Thank you

[chottabhai]

Do you have a specific size? Do you have forten? What kind of model are you looking for. ?

[LiviuM]

Yes I have access to Forten 2000.

I need a model for a tent like the one in the picture below.
I have 4 columns at a distance of 20m x 49m.
I have 2 or 3 or 4 arches between the columns as required. For now I don't know the required/best spacing. I've read somewhere it's about 8 m.
The height about 20m, according to fabric and minimum required.

It doesn't have to be a built one, just an example of input and output. I have no experience in working with Oasys GSA or Forten so the input for me looks very difficult and strange compared to what I'm used to Sap, Etabs, Axis, Advance Design... . Also I have no experience in tent design, I'm afraid I might miss something.

At first I need an analysis model of the fabric, a form finding.
After an analysis model with the fabric and loads to get the design forces for the arches, columns and cables.

The big unknown is the fabric design+cables, I have no issues with steel design.
I'll carry out the design of arches and columns in a different software, here those can be modeled as single frames or joints, it's not clear to me what type of objects are supported.




Thank you

[petko666]

Hello ,

I'm currently designing tensile structures using GSA and I'm familiar with Forten also . I don't have such a model , although in the near future I would have to deal with a circus tent .
But what I can say to you is find someone who has experience with such structures , especially one of such size . It's pretty serious work and if you don't know exactly what you're doing , it may have serious consequences .

[chottabhai]

i true petko666 if you are going to be getting into tensile structures, you might as well get the whole way.. the prestress governs your shape, your form, also your analysis, as the amount of prestress you put on the structure dictates your deflections, and in a way the stability of the entire structure. Predicting the load incident on these kind of structures is also critical since it will eventually change your prestress. This is a ridiculous back-and-forth effort for most engineers, as there is no right-or-wrong nor some code or thumb-rules to follow in their designs.

But on the other hand, with tent structures such as these, you have a very high curvature for the structure, also its going to be designed as temporary, so you can make do with a lot of loading for permanent structures - or not... as the client / design dictates.

Then there is detailing, which will be very different as compared to conventional structures, and much different considering that its a structure that is going to be taken down and put up a lot many times. This changes the detailing of the structure.

Another thing. Forten 2000 is a pretty old software to use in today's date. ixForten 4000 is out and it analyses steel and membrane together, and that should be the approach for such a tent, as the stability of the structure is going to be dictated and dependent on the cables and the membrane. Also, excessive deflections may be permissible in the steel, but will not work for the membrane, and if you are doing that across softwares it will be hell to put deflections of the steel structure back to your membrane program and run an analysis again!!

get someone with a bit of experience. Just getting the mesh will not solve the problem.

[LiviuM]

Thank you for your replies I'm aware of all you said.

At this moment I don't have access to a newer version of Forten. Also I have access to Oasys GSA, the one available on this forum.
If you're aware of a better software trial version or fixed, please post it in software section.
I can buy software only after I do preliminary design (material list). Until then only trial or fixed.

In the past people were solving this with soap bubbles. If I can't do it with software, I'll have to use my camera and some shampoo .

Please post model and/or calculation notes, not your concerns. We can discuss those in engineering problems. You can add your comments to a posted model what it has and what lacks.

If you can't share a work model share a university project, whatever you have and it's well done according to your experience.

Thank you.

[chottabhai]

Livium,
you are correct that they used to do it with soap bubbles, but the amount of time they used to take and the inaccuracies in the design was monumental as compared to what we achieve with today's software.

i run ixForten4000 and have an official version. Unfortunately it cannot give an output to 2k. So even if i generate your model in this version, it may not be of use to you.

what i suggest is that you create a dwg / dxf model of the steel structure / boundary as you want, i can create the mesh for you and give you pre-stress forces. Then you can use the mesh in any FEM program, apply the forces and get your output. is that fine??
I am also attaching a calculation example of a small project. Hope its of benefit to you.

also kindly treat these files as confidential, they are for an existing project.

T&R,
chottabhai

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