ETABS manual meshing

[vinnunsam]

Hi Jaks,

Slightly deviating from the topic, i just wondered if you have a model of a high rise structure in .rtd extension. I mean to ask you that if you have a model file for Robot Structural Analysis and if you do can please upload it.

Hi, Guys

I had done meshing by using two softwares...

Import the dxf file into ROBOT, you have a meshing option there which will mesh the areas into rectangle/quadrilateral, from there saveas dxf again and import into ETABS. But after importing check for overalping areas if any. It gave good results and finer meshing for me.

You can try the above.

Regards,

Jaks

[jamessharp]

thanks guys
but even when i do automesh for the slab of type (deck) it is giving me unrealistic displacements
and when using the shell instead of membrane or deck it gives good displacements but it does not distribute loads realisticly ( suppose i have one way load distribution slab , if i choose shell it will distribute the loads to the joints over the beams and i will get almost the same M33 in the four beams around the slab but when using deck or membrane i will have the loads distibuted the right way but with huge displacements)

[iceman84]

If you want bending moment in beams use membrane elements. If you want slab bending moments use shell elements. You can't get all the results from only one model. You have to do 2 separate models for slabs.

[jaks]

Hi, Vinu...

I dont think you can import the whole model from *.rtd to etabs... but if you want to import floor wise then you can through *.dxf format.
Specialists please comment if I am wrong.

regards,
Jaks.

Hi Jaks,

Slightly deviating from the topic, i just wondered if you have a model of a high rise structure in .rtd extension. I mean to ask you that if you have a model file for Robot Structural Analysis and if you do can please upload it.

[usmancvle]

Hi,
Can anyone explain me what is the basic difference between Membrane, Shell and Plate in Etab? when one should use Membrane, shell or Plate? how we can decide what to use? what is the difference in the results in the three cases?

[jcoronellr]

Regards

The membrane element has three degrees of freedom (X and Y movements more twist in Z) while the shell element has 6 degrees of freedom (3 rotations + 3 shifts). Now which to use depends on the situation.

For example if you want to model a building multistory reinforced concrete it is best to model the slab as a membrane with the rigid diaphragm condition, thus the function of the slab is only to distribute both vertical and horizontal loads. Slabs then modeled independently, using shell elements but considering only the degrees of freedom of movement in Z plus spins X and Y. The reasons for considering the building model as a membrane for unwanted tiles are basically two: 1) The model has many fewer degrees of freedom, thereby reducing analysis time and 2) If you do not make a suitable mesh to model the slabs with elements shell loads applied to these not be transferred correctly to the resistance elements (walls and frames).
As for the common wall is modeled with shell elements, but watch the results as it recalls that these have practically no stiffness out of his plane.

Eye in the case of the balconies, you can not use membrane have vertical displacements.

For walls clearly must take the shell element. Now generally applies the same element (shell), both for walls and slabs.

Jaime

P.D. Please excuse if my English is a bit entangled