Ansys-connecting a beam to a base slab

[idly123]

Hello,
Iam modelling a overhead water tank. The tank has a bottom ring beam all along the circumfrence . This has to be connected to the base slab. for bottom ring beam i have used beam elements and for base slab i have used shell element.also how do i join the base slab with the cylindrical side wall of the tank. could any one tell me the step by step procedure. since iam not much familia with ansys
thanks and regards
raj Raj

 

[dharni]

Dr.Raj,

I am also not familiar with Ansys but Defining local elements on surface, curves, edges are common in all the FE softwares.

The first thing I believe is to use solid brick elements instead of shell, as the normal thickness of water tank slab is 100-150mm and so it would be nice if you use brick elements so that you can check the stress distribution along the thickness as you have to provide Reinforcement on both outer as well as inner.

For brick elements you need to create a section with thickness of slab and side wall. define 2D(shell) elements on that section and revolve all the shell elemtns to 360 to get solid brick elements, you can defined no. of copies(no of ele)along the perifery while defining it.

still if you want to model it with shell then the first thing you need to do is to define no. of elements on the curve/edge where slab and side wall meets this will model exactly same no. of elements and node location on junction. after that you can merge the duplicate nodes.

Hope this will help you.

 

[corus]

I would model the base ring with shell elements as you have already modelled the tank with shells. This solves a lot of problems that occur with mixing beams and shells with offsets and links and so forth. The tank and base ring will then be one structure. If you wish to include the base slab in the model rather than simply restrain the base ring then you can add the slab to the existing shell structure to make one complete shell structure. As the slab is relatively thick, however, offset the shells by the mid-point of their thicknesses and use CERIG to join the nodes of the base ring to the nodes of the slab, ie. equate their displacements allowing for distance apart. It is better if the slab has a line image of the base ring so that the nodes can be better matched.