Dynamic relaxation with non-linear springs

SOFiSTiK Teddy
1

Hi all,

I am running a dynamic relaxation scheme following the example files and I want to include the compression only-springs that I have in my model in the analysis. When I do so however, I get an error message saying:

+++++ error no. 634 in program RADB
Nonlinear springs in group 21 should not have a stiffness proportional Raleigh damping GRP RADB,
because the damping already comes from the nonlinear effect.
RADB would use a may be high linear cp for the damping what would catch forces unexpectively.
If aou want a damping in addition to the nonlinear spring, please input a linear spring
with SOFIMSHA SPRI CP=1 and DP parallel to the nonlinear spring.

When I turn off the group in the RADB line it works fine.

 GRP 21 off  RADB 0.001

But is there a way of including the group with the springs in the analysis without giving them a specific damping factor? Something like:

SYST PLC #plf PROB TH3 FMAX 0.5 TOL -0.01
  GRP 21 off  RADB 0.001 
  GRP 21 YES
  LC #lf FACD 0.0001 TITL 'Relaxation with dynamic damping'

Thanks for your help.

Best,
David

2

Hello David

You can turn the error message into a warning with the command:

CTRL WARN 634

But please check your results for abnormalities.
Normally you should not use a stiffness proportional Raleigh damping in combination with nonlinear effects of a spring.

Best regards
Frederik Höller
Your SOFiSTiK Support Team

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