General Mechanical

General Mechanical

Transient analysis of a rc bridge – large deformationare active

    • lino89


      I'm performing a transient analysys of a simply supported reinforced concrete bridge. At the end of solution, the following warning appears:

      "large deformation effects are active which may have invalidated some of you applied supports". When i look at the total deformation, the rebars are non subjected to deformation.

      I tried these operations:

      - rebars are modeled as LINK 

      - create two mesh size, one for concrete body and one for rebars (reabars are one element size);

      - create multiple bonded contact between concrete body and rebar.

      Could someone help me to undestrand the problem?

      I attached a screenshot of deformation and .wbpz (R19) file

    • peteroznewman


      1) In the archive, the Bonded Contact was suppressed. I unsuppressed it.

      2) The rebar is not centered in the concrete. This is not a problem, just wanted to let you know. You should have at least two elements through the thickness of the top sheet.

      3) I don't recommend bonding Edges to Bodies as you have done.

      4) If I change the Formulation to MPC I can plot the Connection Elements being used. The red lines in the plot below show how the Edges are being connected to the Bodies, only at the vertex points on the line bodies.

      That is why there is no real benefit of the rebar, the concrete is not connected along the length and you get this:

      5) One way to get rebar to bond to concrete is to slice the concrete up into pieces that share an edge with the rebar. In the image below, I have added two planes and sliced all the bodies so that the concrete shares an edge with one rebar. If shared topology is working properly, there is no need for Contact.

      6) Add Mesh Controls to force the line body and the solids to have the same node spacing along the length. Use Node Merge to have the line body connected to the solids without using Contact.

      An alternative to slicing through all the solids to merge nodes is to use the Reinforcing feature. I have never used that but it allows link elements to be connected to solid elements without sharing nodes. Look up Reinforcing in the Mechanical APDL section of the ANSYS Help system.

      Here are the instructions for opening the above link for the Student license.

      An ANSYS 2019 R3 archive is attached.

    • lino89

      Thank you Peter,

      i read about "Reinforcing" feature but it's not simply to use. By the way, i took your advice and the model is now running.

      Best regards

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