Coordinate systems

[mariantonietta2]

Hello Frank and Silvia,

I'm quite confused about the coordinate system. I modeled a simple 2D cantilever beam with a rotational spring to simulate a fracture damage. My model with the global coordinate system
is

|_______@___________
|

^
|
| Y
|----------->X


In manual at page 284 the local coordinate system respect to global one is

Zlocal^ ^ Ylocal
^ l /
l l /
l Yglobal l/---------------> Xlocal
l
l--------------->Xglobal


I used a simple “geomTrans Linear 1”

I want to define the rotation of the spring in direction of Zglobal, so
if a used the indication in page 224 I would use as direction of material of "zeroLenght" element the direction 5 and for “equal SDOF” the dof numbers 1 and 3.
In that case I obtain an error

“WARNING BandGenLinLapackSolver::solve() -LAPACK routine returned 15
WARNING NewtonRaphson::solveCurrentStep() -the LinearSysOfEqn failed in solve()
StaticAnalysis::analyze() - the Algorithm failed at iteration: 0 with domain at load factor 1
OpenSees > analyze failed, returned: -3 error flag
-3”
that I didn´t understand.

In the other hand in example "ZeroLength3.tcl" on website the rotation is indicated using the global reference system (so in different way as indicated in the "OpenSees manual" on page 224) and for this reason the direction of rotation used to define the “rotational spring” is -6, as should be in the the global reference system.

I would only say that when I continued the beam analysis with a dynamic one using the local reference system to define the zeroLenght element I obtained other errors.

Could you explain me what reference system I should use to define the rotational spring and the meaning of static analysis error too.

Thanks
M

[fmk]

you want dir 6 .. here is an example.

[code]
model basic -ndm 2 -ndf 3

set width 100

node 1 0.0 0.0
node 2 0.0 0.0
node 3 $width 0.0

fix 1 1 1 1
fix 2 1 1 0

geomTransf Linear 1
element elasticBeamColumn 1 2 3 360 4030 8640 1

uniaxialMaterial Elastic 1 1000
element zeroLength 2 1 2 -mat 1 -dir 6

pattern Plain 1 "Linear" {
load 3 0.0 [expr -2] 0.0
}

system BandGeneral
constraints Plain
numberer RCM
test RelativeNormUnbalance 1.0e-8 3 1
algorithm Newton
integrator LoadControl 1.0
analysis Static
analyze 1

reactions
print node 1 2 3
[/code]