topic Re: Model warnings in Robot Structural Analysis Forum

Model warnings

Anonymous — Wed, 23 Jul 2014 10:04:48 GMT

I have 3 warning after calculated a 3 storey RC frame:

-incoherent mesh on edges

-cohesion of the calculation model has been provided by definition of kinematic constraints in incoherent points of finite element mesh

-linear load as not been applied to a pannel

I have tryed to follow other post and change the mesh settings but it is even worse.

I have attached the model file:

http://www.filemail.com/t/36154234cbb54dc9834ae45ca2b1d2d6

thank you

Re: Model warnings

Rafal.Gaweda — Wed, 23 Jul 2014 11:04:53 GMT

-cohesion of the calculation model has been provided by definition of kinematic constraints in incoherent points of finite element mesh

http://forums.autodesk.com/t5/Robot-Structural-Analysis/Structure-verification/m-p/3334787#M2792

-linear load as not been applied to a pannel

Check coordianates of your lines create for loads application or apply loads this way:

Re: Model warnings

Rafal.Gaweda — Wed, 23 Jul 2014 11:18:41 GMT

-incoherent mesh on edges

Model is inaccurate

See video how to correct mesh and geometry:

Meshed model attached

Re: Model warnings

Anonymous — Wed, 23 Jul 2014 11:30:29 GMT

Thank you.

I don't understand what you have done with the walls using the spreadsheet. Is it something I will need in future for other models to avoid errors?

Re: Model warnings

Rafal.Gaweda — Wed, 23 Jul 2014 12:40:10 GMT

I have corrected coordinates. Wall were not made in one plane

Re: Model warnings

Anonymous — Thu, 24 Jul 2014 09:55:17 GMT

Thanks again.

I have removed few columns and run the calculation without re-mesh the slab. The max moment is 75.

Then I have meshed the slab following your instruction. The moment is decreased at 60 and I don't understand why. (the columns removed are at the opposite of the building, far from the max moment point).

Shall I trust in the new mesh with the lower value?

thank you

Re: Model warnings

t.sautierr — Thu, 24 Jul 2014 10:00:46 GMT

have you same density of mesh?

is coarse, maybe the new one misses the peak ...

Re: Model warnings

Rafal.Gaweda — Thu, 24 Jul 2014 10:04:59 GMT

FEM results strongly depend on meshing

Re: Model warnings

Anonymous — Thu, 24 Jul 2014 10:16:28 GMT

Yes the mesh size is the same... 1 m

Re: Model warnings

Rafal.Gaweda — Thu, 24 Jul 2014 10:17:49 GMT

???????????
I do not understand. File please.

Re: Model warnings

Anonymous — Thu, 24 Jul 2014 10:38:57 GMT

http://www.filemail.com/d/lmrjcywrzmtyycu

I have attached both model. P3 is meshed by you.

Thank you

Re: Model warnings

Rafal.Gaweda — Thu, 24 Jul 2014 14:49:54 GMT

This is what I see :

Re: Model warnings

Anonymous — Thu, 24 Jul 2014 15:03:30 GMT

This is the map for Y moment at 1st floor.

Re: Model warnings

Rafal.Gaweda — Fri, 25 Jul 2014 08:46:00 GMT

I wrote before: "FEM results strongly depend on meshing"

Re: Model warnings

Anonymous — Fri, 25 Jul 2014 16:05:22 GMT

Thank you Rafal.

How can I connect a steel frame on top of the concrete slab?

Re: Model warnings

Rafal.Gaweda — Mon, 28 Jul 2014 07:59:02 GMT

How can I connect a steel frame on top of the concrete slab?

?????????????

Re: Model warnings

Anonymous — Tue, 29 Jul 2014 14:55:59 GMT

Hi Rafal,

Thanks for your advise so far. This building is proposed as a 3-storey RC, (+0m to +9m), with a 2-storey steel frame on top (+9m - +15.25m).

Looking at level 9.0, the steel frame columns over do not line up with the RC columns below. Therefore , my question is, is it possible to define pinned supports to the steel columns, on the RC floor at level +9.0m? Other posts suggest the use of rigid links, but I cannot understand this.

The other option is to create a separate steel model, and apply the reaction forces to RC model, but i would prefer just to have one model if this is feasible.

Many thanks, Franco

Re: Model warnings

Rafacascudo — Tue, 29 Jul 2014 15:07:18 GMT

Use "rigid links" to link the concrete columm top node to the steel columm botton node. Then just use "bar releases" to pin the botton part of your steel columm

Re: Model warnings

Rafal.Gaweda — Tue, 29 Jul 2014 15:20:05 GMT

Thanks for your advise so far. This building is proposed as a 3-storey RC, (+0m to +9m), with a 2-storey steel frame on top (+9m - +15.25m).

Looking at level 9.0, the steel frame columns over do not line up with the RC columns below. Therefore , my question is, is it possible to define pinned supports to the steel columns, on the RC floor at level +9.0m? Other posts suggest the use of rigid links, but I cannot understand this.

Possible solutions:

The other option is to create a separate steel model, and apply the reaction forces to RC model, but i would prefer just to have one model if this is feasible.

http://forums.autodesk.com/t5/Robot-Structural-Analysis/Only-reaction-for-new-model-API/m-p/3659280#M8321

Re: Model warnings

Anonymous — Wed, 30 Jul 2014 08:17:19 GMT

Rafal,

Thanks for your reply. However, the steel columns do not line up with the concrete columns below. The slab at +9.0 is required to transfer the loads.

Can rigid links be applied to the actual floor slab?