Can truss elements be used in 3D modeling?

[jgeis]

I created a 3D model with truss elements and am getting the following error:

WARNING BandGenLinLapackSolver::solve<> -LAPACK routine returned 8
WARNING NewtonRaphson::solveCurrentStep<> -the LinearSysOfEqn failed in solve <>
StaticAnalysis::analyze<> - the Algorithm failed at iteration: 0 with domain at load factor 0.1
OpenSees > analyze failed, returned: -3 error flag
done with analysis

I simplified the model into a smaller 2D system (with truss elements) and had no problem running the analysis. However when I change the system into 3D coordinates, the analysis fails.

Does anyone know if truss elements can be used in a 3-dimensional Opensees framework? Thanks.

[vesna]

Yes, you can use truss in 3D models.

The error you are getting indicates that you do not have enough constraints in your model.

[jgeis]

Thank you for the assurance that truss elements can be used in 3D models. I will apply more constraints to my model.

[abolfazlabedi]

Hi.
I saw your answer to " jgeis " regarding to use truss elements in 3D models.
You mentioned there that the number of constraints are low and maybe this cause the solver errors.
I have a similar problem but my model is not unstable.
My goal is doing an IDA analysis on Domes (spatial/space one), but in modelling I faced errors in doing a simple linear static analysis.
I made a simple 3D truss for solving this error more easily.
Can you check this model in OpenSees and solve its problem?
I know this is a big requeat from me but it's very important.
Thank you so much.
# Units: kg, m, sec
model BasicBuilder -ndm 3 -ndf 6
node 1 0 0 1
node 2 0 1 0
node 3 1 0 0
node 4 1 1 0
node 5 0 0 0
fix 2 1 1 1 0 0 0
fix 3 1 1 1 0 0 0
fix 4 1 1 1 0 0 0
fix 5 1 1 1 0 0 0
pattern Plain 1 "Linear" {
load 1 0.0 0.0 -1 0.0 0.0 0.0
}
puts "ok1"
mass 1 0.5 0.5 0.5 0.000000001 0.000000001 0.000000001
uniaxialMaterial Steel02 1 24e6 2.1e10 0.01 10 0.925 0.15 0.005 0.01 0.005 0.01
element truss 1 1 2 0.001 1
element truss 2 1 3 0.001 1
element truss 3 1 4 0.001 1
element truss 4 1 5 0.001 1
constraints Transformation
numberer RCM
system BandGeneral
test NormDispIncr 1.0e-6 30
algorithm Newton
integrator LoadControl 0.02
analysis Static
recorder Node -file nodeDisp.out -load -node 1 -dof 1 2 disp
analyze 1
print node 1

[vesna]

Try adding a full fixity to fixed nodes:

fix 2 1 1 1 1 1 1
fix 3 1 1 1 1 1 1
fix 4 1 1 1 1 1 1
fix 5 1 1 1 1 1 1

or change constraints to Penalty.