Modeling of high-rise building with "transfer plate" 1

[ranakuet]

Hi
I am going to analyse a high-rise building with transfer plate system in context of earthquake by Etabs. Here I face a problem that is connection of Transfer plate and column which is omitted below(to get a higher spacing of column below transfer plate). If I use beam with the plate/slab it works but this model does not give proper analysis of transfer Plate behavior. In this case how can I model the building..

A B c
-------
| | |
-------transferplate
| D |
-------

Here BD Column is concern. How can i connect Column edge D with the Transfer Plate... Please Help me.

 

[slickdeals]

If I were you, I would use shell elements to model the transfer floor and manually mesh it. This way you can ensure that the column above is connected to the transfer floor and ensures proper load transfer. Manual meshing will also help you to refine the mesh as you need it in case you have to look at stresses.

HTH.

 

[ranakuet]

Thanks slickdeals
I don't know how shell elements can solve this. Slab isn't one kind of shell element ?

Actually I would like to explain my problem in details.I use Etabs 8.5.0 nonlinear version. Here in GUI options are available to me and from grid and different view, Beam, column,slab, shear wall can be arranged easily.Again by defining deck slab can be easily modeled. In manual it is said the software meshed the elements as it need to proper solution.If beam column arrangements are proper then Etabs shows slab stress etc.

Now In my particular problem (Transfer plate analysis) I connected column "BD"(above line diagram) with beam at B point but there is no beam below the column so D points remains free(which should be connected with Transfer plate). After analysis it was seen that the column BD settled down freely and the transfer plate does not show any stress variation.

But if I connect the Columns with Beams at transfer plate level then it works that mean the software shows transfer plate stress properly.

How can I get ride of this problems.........

 

[slickdeals]

You have to manually define your meshing lines. I will post a detailed reply later. Is it possible for you to share your model so I can fix it?

 

[ranakuet]

Thanks again

http://dsa10.fileflyer.com/d/9d1d4c...c78579ba5/38a5/t85a2B7/TransferPlate-test.EDB

This is a test model of a transfer plate at the 1st floor of the 2 storied building.Here middle column of 1st floor were omitted in ground floor(to get a free space).

Problem is that the column at the middle is free at the bottom(there is no joint with Transfer plate and the bottom of the middle column).

 

[slickdeals]

Ok, I fixed your model.

The problem is that you were using a membrane element to define your slab. A membrane element has only in-plane stiffness, no out-of-plane stiffness.

You should define your transfer plate as a shell element using the actual thickness for "membrane" and "bending" properties. In your example model, redefine you slab element to "SLAB1".

Draw meshing lines using "NULL" lines. Make sure you connect the column that is being transferred. Once this is done, go to Assign --> Shell/Area -->Area Object Mesh Options. Under Floor Meshing Options, choose Auto Mesh into structural elements and check mesh at beams and mesh at wall and ramp edges. Leave the other two unchecked.

This should take care of your problem.

I am uploading a .e2k file. Try to import and see if it works. Otherwise, follow my steps above.

 

[ranakuet]

Hurray it works