#### Topic: Anchor plate inside concrete volume

Hi,
I'm trying to model a part of an arch bridge, namely the anchorage of the top hangers in the mid of the arch, in ATENA/GiD.

A ~2m segment of the arch is modelled with volume elements (cross-section w:0.6m & h:0.9m).
The steel anchorage plates have dimensions 150x150x50 mm.

So, I'm looking for advice on how to:
- Model the steel plates inside the concrete (I guess I need to subtract/intersect, but did not get this to work in GiD)
- Release the contact in the top/side of the plate, to only carry forces on the bottom side (mainly compression).

Thankful for any input!

Best Regards,
Mattias

#### Re: Anchor plate inside concrete volume

Hi Mattias,

Hope it is not too late

I would recommend to create the model in any 3D CAD software and then importing it into GiD. I find it much more convenient rather than creating complex geometry in GiD.

I couldn't get the second question. Would you sketch it?

Br, Pavel.

#### Re: Anchor plate inside concrete volume

It managed to create the geometry as I wished, but will consider using another software to create more complicated geometries in the future as you recommend.

The second question is related to releasing the contact (interface elements with low stiffness?) between steel and concrete above the an anchor plate, also the shear on the sides.

I made a try to explain better in a sketch: https://ibb.co/1bHfssd (Not sure if this is an accepted way to link a figure?)

Best Regards,
Mattias

#### Re: Anchor plate inside concrete volume

Mattias,

If the force is one-directional, I would just define contacts (Master-Slave or shared surface) only where compression is anticipated. Sad but true, you would better avoid using interfaces if there is such possibility. However, if you don't know exactly where tension occurs then you have to use interfaces. And yes, you are right, you need to define an interface with a low tensile resistance.

As to side surfaces, I would keep them not attached to concrete at all since they shouldn't contribute to the anchor resistance.

I wonder whether you have a 2D or 3D model? If your structure is similar along its width, I would recommend using 2D at least for model tuning. Later you can make a 3D and it would be way easier to define all boundary conditions when you have your 2D model working.

I made a sketch how I would model it myself: https://ibb.co/4RZjjHy
I would divide concrete into smaller pieces to have concrete as brick volumes (to mesh them with "Structured" type). Then each contact side can be defined separately: side surfaces may be not connected, pure compression can be master-slave or even interface (just for easier representation of contact stresses), top surface can be either not connected or interface in case you anticipate some compression at corners of anchor plate.

Interface definition is a separate topic which is not that simple (this is why I recommend avoiding them ). This video can be helpful: https://www.youtube.com/watch?v=8HUcL_McfJo

#### Re: Anchor plate inside concrete volume

Hi again,
The force is assumed to be one-directional.

I'll try to do as you suggest with the conditions around the plate, thanks!