General Mechanical

General Mechanical

RC Beam: Absolute Beginner

    • santosh91

      Hi everyone,

      I have just started to model the RC Beam using ANSYS APDL. For the RC beam, I am using SOLID 65, LINK 180, and SOLID 185. SOLID65 for concrete, LINK 180 for reinforcements and SOLID 185 for support and loading plates. I entered the material properties. I created the beam by volume: first beam and then support and then loading plate. After that I Glued the all three volumes. Then I copied the end areas to the appropriate distances to get the line for reinforcement. Then I divided the volume by area and got the lines. By using component manager, I selected the top, bottom, and shear reinforcement and made new component.

      For the meshing, first I mesh the lines of edge 25mm for the whole model. Then I put the attribute for each volume and reinforcement and using sweeping mesh to get rectangular mesh. (I don't know if there is any other way to get rectangular mesh of different height, length and breadth of mesh element). After the meshing, I merged everything from nodes to volumes.

      Then I applied symmetry boundary condition at the right half of the beam (on nodes Ux=0) and applied UY=0 and Uz=0 at the middle nodes of the supporting plate. In the case of applying load, I am applying constant load FY in negative direction but applied in middle line of nodes of loading plates (not sure whether this is right way to applied the load). From the experimental result, the maximum load is 45kN. So, I applied the same amount of load.

      I put the solution control values as guided by You tube videos with convergence tolerance of 0.05 for U. And then tried to solve the model but got convergence error.

      Am I heading toward right way to model the RC beam?

      How can I resolve this convergence error?

      How can I get load deflection curve?

      My ultimate goal is to apply CFRP to the beam.

    • Bill Bulat
      Ansys Employee
      Hi Santosh,It should be possible to post process the displacement of the unconverged results, and, if you used OUTRES,ALL,ALL before solving, stresses and strains of any converged results that were obtained before the unconverged sub step was attempted. Sometimes looking at the results leading up to the unconverged result can help you diagnose the problem (identify it's location and the way in which the model was behaving under load until the convergence failure occurred).nnLegacy SOLID65 has a built-in smeared representation of rebar that you might consider to simplify the modeling process:nnThe newer, recommended way to model reinforced materials is to use REINF263 (smeared representation) or REINF264 (discrete) reinforcing elements:nnnIf you prefer SOLID65 the attached (very old) document may be of some use to you.nnArraynAnother trick is to issue NCNV,0 prior to solving (so that the solution doesn't stop simply because convergence criteria haven't been met). You may end up with an unconverged result but at least you can post process it to see how the modeled structure behaved under load.nTry imposing a displacement instead of a force - that's usually more numerically stable. You can post process the forces at the nodes you applied the displacement to as a way of getting the force-deflection relationship.nBest,nBillnn
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