• Registered: 2010-03-09
  • Posts: 26

Topic: Boundary conditions

Hello,

As stated in ATENA THEORY, there are simple support and complex support boundary conditions i.e. Dirichlet type , boundary conditions that prescribed displacement.  There is also simple load boundary conditions i,e Von Neumann type for prescribe force.

May I know the boundary conditions for the example in ATENA Program Documentation Part 3 Example Manual 2.4 Leonhardt's Shear Beam (LSB). Which boundary conditions  adopted for LSB for the theory mentioned above? the Dirichlet type (simple support or complex boundary support conditions?)

For my problem, I am modelling in ATENA 2D for a simply supported beam using a fixed support  (restricted in x & y direction) and 2nd support is restricted in y-direction only. As for the theory of boundary conditions, which should I adopt?

Please advise.

TQ

Quote Post 1

  • dpryl
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  • Registered: 2007-07-13
  • Posts: 1,107

Re: Boundary conditions

Dear Irene, I would recommend to look at the shear beam example included in ATENA installation:

Engineering 2D %ProgramFiles%\CervenkaConsulting\AtenaV4\Examples\ATENA Engineering\Tutorial\Beam Iso.cc2
Engineering 3D %Program Files%\CervenkaConsulting\AtenaV4\Examples\ATENA Engineering\Tutorial\Shear beam 3D.cc3
Science-GiD %ProgramFiles%\CervenkaConsulting\AtenaV4\Examples\ATENA Science\ATENA-GiD\Tutorial.Static3D\ShearBeam3D.gid

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Quote Post 2

  • Registered: 2010-03-09
  • Posts: 26

Re: Boundary conditions

I understand how the boundary conditions are defined from  the tutorial examples. But, may i know in which category of these type of boundary conditions? Is it simple or complex supports or master slave boundary conditions (mentioned in ATENA THEORY)?

TQ

Quote Post 3

  • dpryl
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Re: Boundary conditions

Dear Irene,
the terminology is general for partial differential equations. In static analysis, Dirichlet condition means prescribed displacement (zero or nonzero), Neumann corresponds to prescribed force (again, regardless if zero or nonzero).

The "complex support" term in ATENA means a condition connecting several degrees of freedom (DoFs), while "simple" means a condition which binds a single Dof. The complex supports are used for master-slave connections (= contacts between macroelements with incompatible meshes = connecting/mixing the same DoF of multiple nodes together), sliding supports in other directions than the global axes (i.e., mixing for example the X and Y DoFs of a single node for a 45-degree sliding support), and other special situations.

If you are interested in the detailed implementation of each BC, look into the Input File (.inp). While doing so, you may like to use the ATENA Input File Format Manual for reference.

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Quote Post 4