#### Topic: 3-D Modelling of Pull Out Test with Reinforcing Bar Ribs

Dear Dpryl,

We are modelling pull out test according to AS3600. The reinforcing bar is embedded inside a concrete cylinder of 150 mm diameter. The bar is then pulled out axially. We are looking in to the performance of different rib patterns.

I have read your suggestions recently given to Fcil under the topic "Pull-out - Principal stress's jump". Since our study is focusing on the performance of rib pattern, we need to design the rib pattern in 3D. We tried to do in ANSYS where the rib patterns are drawn in Solid 3D and then imported to ANSYS. But we did not get result.

I am confident using ATENA 3D, but I did not find how to draw the bar rib pattern in ATENA and then do the pull out test.

Regards
Ahsan

#### Re: 3-D Modelling of Pull Out Test with Reinforcing Bar Ribs

Dear Ahsan,
1. please note that rib dimensions are typically smaller than the aggregate size of the surrounding concrete, which makes the assumptions for concrete as a homogeneous continuum problematic, as small elements in the concrete are needed to fill the gaps between the ribs.

2. If you try to explicitly model the bar using 3D elements, including the exact rib geometry, you are likely to end with some extreme number of mesh elements. And probably end without a usable result (as you have ended with ANSYS).

3. As the usual approach = representing the bond with a bond law applied to a 1D bar element representing the bar seems not interesting for your purpose, we can try to help you prepare some model based on more detailed approximation.

4. If you send us sketches illustrating 2-3 rib geometries, we can try to help you finding a reasonable modelling approximation.

4.1. My first idea is what we have already used with success a few times, mostly for shear keys: model the bar with smooth surface, but divided by lines representing the ribs. Then, apply Interface Material to connect the steel surface to the surrounding concrete, and, additionally, connect the lines representing the ribs to the concrete using Master-Slave.

4.2. Even with this simplification, you are likely to need elements smaller than the aggregate size. To reduce the adverse effects implied by this broken assumption, we can recommend the (relatively new) option "Crack Spacing Min".

4.3. We recommend to prepare your model in GiD, and use ATENA Science - ATENA Studio for the analysis.