Hi,

if you are going to simulate a wall. then any plane-stress element would be fine (see http://www.oofem.org/resources/doc/elem … e11.html). The reinforcement could be simulated using 2D truss elements. Moreover, the mesh for "concrete" can be independent of reinforcement, which can be added into the model using hanging nodes.

Borek

Hi,

1) unfortunately, the plane stress elements can be used directly only in xy plane. The extension into the arbitrary plane is not difficult, bu requires some coding.
2) perhaps you can use the shell element (rershell) that could be placed anywhere in 3d and you can fix  DOFs related to bending, so that only membrane part will be considered. Rershell element is just superposition of constant strain plane stress triangle and constant curvature triangular plate element. But this is less elegant, but probably the only solution, if you want to avoid some coding.

I can provide some example of plane stress problem with reinforcement, if you want. The modification for rershell element should be simple. Let me know.

Borek

Hi,

attached you will  find enclosed a simple example of 3D model of a simply supported beam with two reinforcing bars, illustrating the use of hanging nodes to introduce reinforcement.

Borek

I know its too late to ask considering the date on the post.

But where can I have that example, if it is available by any chance.

I am new to oofem and want to learn modelling RCC structures with non-linear behaviour.(Static and dynamic loading)

Thank you very much for your reply and your time for preparing this example.

My aim at present is to model RCC building and shear wall using oofem. However at present I am more interested in understanding the basics and would invest my time in learning it more than directly going to the final problem.

As obvious, for modelling a RCC building, the feature you suggested would be great to have otherwise it will be very difficult to find out master element for every hanging node. So if you find enough time for this then please do take up this matter.

Ohh ... let me just clear my understanding here...

Does it mean that adding hanging nodes (and connecting elements with different material model) will have no effect in the calculation?
Or in other words, whats the purpose of hanging nodes then? I think I am seriously missing something here.

I just commited code that automatically detects the containing element if you just supply the global coordintes for the hanging node.
See hangingnode03.in for an example. Its about as simple as it could get now

hangingnode03.out
Test of hanging node in with automatic element detection.
LinearStatic nsteps 1 nmodules 1
vtkxml tstep_all domain_all primvars 1 1 vars 2 1 4 stype 1
domain 2dPlaneStress
OutputManager tstep_all dofman_all element_all
ndofman 5 nelem 1 ncrosssect  1 nmat 1 nbc 2 nic 0 nltf 1
node 1 coords 3  0.0   0.0   0.0  bc 2 1 1
node 2 coords 3  0.0   4.0   0.0  bc 2 1 0
node 3 coords 3  8.0   4.0   0.0  bc 2 0 0
node 4 coords 3  8.0   0.0   0.0  bc 2 0 0
hangingnode 5 coords 3  6.0 1.8 0.0 dofType 2  2 2 load 1  2
PlaneStress2d 1 nodes 4 1 4 3 2  crossSect 1 mat 1
SimpleCS 1 thick 0.15
IsoLE 1 d 0. E 15.0 n 0.25 tAlpha 0.000012
BoundaryCondition  1 loadTimeFunction 1 prescribedvalue 0.0 
NodalLoad 2 loadTimeFunction 1 Components 2 2.5 0.0
ConstantFunction 1 f(t) 1.0

Although, at the time of writing this, i now realize it might not always be such a good idea for this application.
There will be two elements defined at that point there the hangingnode is attached. Both master and slave element, and OOFEM won't treat them any different, so it might attach to its own enrichment element.
Anyway, the code can still be usefull if you where to simple att a load at a certain point, or track the motion inside some element.  It would also be possible trivial to extend this to only check elements in a certain region, which might be what you want to do with the concrete+reinforcements anyway.

To have automatic element detection, simply don't supply a master element.

Hello,
I am not sure if this is the correct place to post my question. I want as well to analyse a concrete shear wall and I will apply the hanging node concept that you propose in the current post. I am working on a 2d domain. 
I am using t3d for the mesh generation and  as far as I understood I am going to mesh a patch or a region to create the 3d elements of the concrete wall and a curve to include the 2d trusses for the reinforcement. The latter group of elements will be the hanging nodes and as I understood OOFEM will trace their "master" elements.
However I would like to include in my model a bond-slip law  for the reinforcement.  A way to do it would be with interface elements. In order to combine the hanging node concept should I mesh 3 curves on t3d so that I have 2 curves for the surrounding concrete faces and 1 curve for the bar? Do you know if it is possible in t3d2oofem to produce interface elements?
Apart from this way to introduce the influence of the bond in the model is there another easier and maybe implicit method already implemented in OOFEM?

I would like to thank you in advance