• Registered: 2012-03-01
  • Posts: 4

Topic: Questions regarding stress strain diagram for concrete and others..

Hello..

1- How can I establish a specific stress-strain diagram for concrete? I have tried with cementitious 2 user but I can't figure out where exactly I can enter the values of the stress-strain diagram.

2- Is there a way to determine a failure criteria for the model...(i.e reaching the yield stress in the reinforcement steel or so..)

3- When I use imperial units, I enter all the values with KIPS,...however; when i monitor loads i get it in lbf...and even with uncorrect values ..while for the same model, I get the expected value when I use metric units with the same mesh

4- Finally, according to a previous post regarding monitoring surface reaction..you referred to make the support place rigid enough...I have tried to increase the modulus of elasticity of the plate, but yet, the model isn't stable if i used only one point 

Thanks in advance..I really appreciate your support

Quote Post 1

  • dpryl
  • CC software developer
  • Offline
  • Registered: 2007-07-13
  • Posts: 1,107

Re: Questions regarding stress strain diagram for concrete and others..

Hello, to your questions:

1. you have to define all the functions in the NLCem2User material dialog. Please read the corresponding part of the ATENA Theory Manual and do not forget that the localization strain value is very important - simply said, it controls when the switch from strain-based model to absolute crack opening (or plastic displacement) occurs.

2. I am not sure if I understand your question. If you wish to define an analysis stop criteria, I am afraid currently only convergence errors are supported.
If you ask how to recognize the failure mode, basically do the same as you would with a real structural member or test specimen, i.e., look at the plastic strains in reinforcement near peak load, crack pattern and openings, etc. Just it is much easier in the Postprocessor to look inside the member/specimen...

3. please send us the model along with a description which units or values are incorrect, such that we can reproduce the problem.

4. the "rigid" material should have E modulus about 2-10x that of steel (as you have already understood, a too high elastic modulus can lead to numerical problems). Make the plate thicker and mesh it with large elements if you need to distribute the load more evenly. In some situations, it can make sense to apply the load in 2 points (and sum) instead of a single point.

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Quote Post 2