3D Interface element

[rajib.iitbbsr]

Interested in 3D modelling of Pile-Soil problem, From related topics I could able to find different interace elements which can be used to connect soil with pile element, such as Equaldof; Zerolengthcontact 3D; Beamsolidcontact 3D.

My first queastion is that: Beamsolidcontact 3D element is not incorporated under Opensees manual-2007. The syntax is also not available in net, but 2D syntax is available.
Whether 2D syntax can be followed for 3D after necessary modification? and Will this command will be compatible in Opensees Interpretor ?

Secondly....What is basic difference between these three different interface elements command?

Plz request for valuable help abt these two questions.

[mcganncr]

I'm not very familiar with the zeroLength contact elements, but from a quick glance at the source code, it looks like there are some additional input terms that you need to specify for the zeroLength3D element vs. what is documented for the 2D version. You could probably figure out what these terms are by looking at the source code. A link is available on the OpenSees page. The zeroLengthContact elements were written by Gang Wang and Nick Sitar at UC Berkeley. You may want to contact them for more information if you are interested in working with their elements.

Some elements that we have written at UW have been added to OpenSees for use in beam-to-solid contact in 2D (which really is wall to solid contact) and in 3D (for circular beam cross-sections). Documentation for the BeamContact2D and BeamContact3D elements are posted on the OpenSees wiki. The 3D documentation is at http://opensees.berkeley.edu/wiki/index ... mContact3D

As for the differences between the interface approaches:

When using equalDOF, the nodes you link with this command share the specified degrees of freedom. Essentially, they are stuck together. This approach cannot account for frictional behavior, or any gapping between the pile and the soil.

The BeamContact3D element creates a frictional interface between the beam and solid elements. It was written to consider beams with circular cross-sections only. This element allows for gapping and frictional slip to occur at the interface. This element considers the full kinematics of the beam.

The zeroLengthContact3D element also allows for gapping and frictional slip to occur at the interface.

I think one main difference between BeamContact3D and the zeroLengthContact3D, is that in the zeroLength, the solid elements are in contact with the beam elements, which represent the centerline of a beam cross section. In the BeamContact3D elements, the solid elements are in contact with the outer surface of the beam. The size of the beam is controlled by the radius input parameter. Also, the BeamContact3D element considers the full kinematics of the beam. I'm not sure if the zeroLengthContact3D element does this or not, you would have to look at the formulation.

Hope this helps,

Chris McGann
University of Washington

[rajib.iitbbsr]

Thanks ....for a brief idea....Can anyone provide any .tcl example on 3D pile soil modelling using 3D contact element where pile is modeled circular 3D element and soil is represented by brick element....

Welcome for help...