About meshing techniques 3

[zstone]

which is best way?
In some training manuals of CSI,and video tutorials, shear walls are not meshed.
Complet shear wall in one story is included as one finite element, this reason is for design of shear wall procedure or fore anyother reason, i dont know
i thing that to meshing shear waall is best way, because results will bee more logic and more realistic than in other case(unmeshed shear wall),
sorry for my english
best regards

 

[jugurtha12]

I THINK THAT WE CAN NOT MESH A SHEAR WALL BECAUSE IT IS A STRUCTURAL ELEMENT BUT WE CAN MESH IT ONLY WHEN THERE IS AN OPENING IN THE WALL
SORY FOR MY INGLISH

 

[slickdeals]

Any unmeshed shell element has an artificially high stiffness. It is recommended that you mesh your walls especially if you are designing tall buildings because there will be more flexibility.

You can internally mesh a wall element.

 

[sreichwein]

Meshing a shear wall is much more accurate to the actual behavior. However, complex shear walls in ETABS are extremely tricky to mesh. I usually assign automesh to each wall pier and assign a maximum mesh size equal to 24". The tricky part is getting the mesh to work. You must make sure that all meshed shell element boundaries are attached to an adjacent shell element. If not, you will get errors in the analysis or the model will not run at all. Practice makes perfect, so I recommend playing around with it until you get it down. If you need more information, let me know.

 

[JoeyRachel]

sreichwein: Could you give me some suggestions about how to use automesh? I can not see the option when I try to mesh the slabs.

Thank you.

 

[stressed]

Meshing a shear wall is also needed for creating openings, for changes to section properties and to assist with design since you can assign different piers and spandrels to separate meshed areas. Automeshing is not the way to go in most cases for walls in my experience. CSI needs to rethink the advice that they give users in their videos and user manuals and be clear as to when "object modeling" is a good thing and when it's not. With walls, automatic meshing for object modeling is seldom useful.

Select walls and use Edit>Mesh areas. If you want to mesh only for accuracy and have no openings or changes in section properties, then select the "Mesh quads/triangles into" 4X4 or whatever mesh refinement you want. sreichwein recommends every 24". I think that's a reasonable recommendation, but in my experience, in most cases you don't need to refine the mesh even that fine. Experiment yourself to see if mesh refinement changes results significantly, but in my experience, if there are no openings, meshing by every 4ft or 6ft has been plenty good for most design purposes. But again, experiment for yourself

One other important point - Edit>Mesh areas>Mesh quads/triangles with visible gridlines is a very, very important mesh option for shear walls. Go to elevation view, activate the fill view from set bldg view options, then use Edit>Edit reference planes and Edit>Edit reference lines to add gridlines between stories in order to mesh with precision for openings, etc. The 'Draw windows' and 'Draw doors' options seem like gimmicks to me.. I don't find the draw windows and draw door options useful at all. For that reason, I create gridlines like I want using reference planes and reference lines, then mesh by gridlines in order to create openings and for pier labeling. It's very straightforward and fast once you learn it.

If you have the same opening for multiple stories, you can mesh one wall, then use Edit>Replicate to copy to other stories