Strain-rate dependent material (Abaqus - Concrete Damage Plasticity)?

08 August 2018 5 7K Report

Hello everybody.

Can anyone please help me to resolve the following problem?

I am trying to obtain the structural response of a reinforced concrete column subjected to a blast load by performing a dynamic analysis in Abaqus/Explicit. Since the blast is a dynamic event that occurs in a very short time, the materials characteristics (stress values) should be modified with respect to the strain rate effect.

Can anyone give me some suggestions regarding the input for the Concrete material when using the Concrete Damage Plasticity option?

I have tried to change the stress values as the strain rate increases as shown in attached picture, but then I receive the following error: “DURING THE CONVERSION FROM CRACKING TO PLASTIC STRAIN Abaqus FOUND NEGATIVE AND/OR DECREASING VALUES OF PLASTIC STRAIN. VERIFY THAT THE DEGRADATION DATA UNDER *CONCRETE TENSION DAMAGE IS CORRECT”

Since the plastic strain seems to be evaluated in a wrong manner when using this approach, can anyone suggest me the right way to account for the strain rate effect when using CDP option for concrete?

Thank you.

Mircea D. Botez

Dear Mr. Akram,

thanks for the suggested papers.

I've already searched scientific articles regarding this subject and I'm aware that the concrete behavior can be considered through several mathematical models ( with or without considering the strain rate effect).

I've asked my question here in the hope that someone who actually used this option (Strain Rate dependent data) in Abaqus for the Concrete Damage Plasticity model (I guess that this option in problematic in my case) can give me some recommendations.

Best regards.

Mircea D. Botez

Thank you for the suggestion Mr. Fabian Dwenger .

Unfortunately, this approach seems to generate another error.

If I sort my values as suggested, the program exit with another error: "THE INDEPENDENT VARIABLES MUST BE ARRANGED IN ASCENDING ORDER".

I suppose that this "independent variable" is the rate.

Mircea D. Botez

Yes, those negative plastic strains are the problem.

I've already evaluated the plastic strains values according to the CDP relations available in Abaqus Documentation and the values are below 0 (Hence the first error).

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