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Dear Frank McKenna

How do I use the shell element for modeling Retaining walls.
in openseeswiki I read this sentence,
Shell Element is a 3D element with 6 dofs and CAN NOT be used in 2D domain.

can any body tell me what does this error means: ProfileSPDLinDirectSolver::solve() - aii < 0 (i, aii): (0, 0) WARNING NewtonRaphson::solveCurrentStep() -the LinearSysOfEqn failed in solve() DirectIntegrationanalysis: : analyze<>- the algorithm failed at time 500 http://s6.picofile.com/file/82305698...

i need shell elements for 2d model

please guide me
Where can I find information on the interface elements (in opensees)?

robertwillis wrote: > To simulate the interaction between a structure and soil you can apply > interface elements. Without an interface the structure and the soil are > tied together: > no relative displacement (slipping/gapping) is possible between structure > and soil. By using an interface, node ...

Please, put an example.

wipe #---SOIL GEOMETRY set nssh 3; ##### number of same section in height set h4 4; set numst 9; ## number of story set bay 3.0; set underf 3.0; set underh 3.5 ; set len 200.0 ; set h1 10.0; set h2 10.0; set h3 15.0; set bs 18.0 ; set fw 2.0; set df [expr ($underf*$underh)] ; set dim1 2.0 ; set dim2...

I try to model soil and structure. I don't know how joint soil nodes to structure nodes. I use ContactMaterial2D but opensees shown below error:

:operator/<double fact> - divide-by-zero errorr coming.

I would be grateful if you could help me to solve it.

i want to model frame (2D)that underground openings have Retaining walls.
how can I model two of the following:
1-Retaining walls
2-Forces perpendicular to the wall

i have problem with Soil-structure model.
i want to model soil and structure in 2d but i do not know how soil node and structure node contact together.

any body can help in this case????!!!!
Interface elements Contact Elements in OpenSees

do you find any thing?