element zeroLength

[ehsanala]

hi
Please explain about part orient in element zeroLength command with an example.

thank you.

[shenxian]

hi，
http://opensees.berkeley.edu/wiki/index ... th_Element
element zeroLength 1 1 2 -mat 1 -dir 1 -orient 1 1 0 -1 1 0; # truss tag 1 between nodes 1 and 2 acting in local direction 1 defined with material 1. Local direction 1 attains 45 degrees with global X axis .

i want to know the :orient 1 1 0 -1 1 0, how to calculate in 3D model.

[ehsanala]

Thank you
How this numbers are obtained?(-orient 1 1 0 -1 1 0)


Please explain this line to me.
element zeroLength 133 101 128 -mat 3 3 3 4 -dir 1 2 3 6 -orient 9144 3962 0 -3962 9144 0

[fmk]

as for the 1 1 0 and -1 1 0 .. they are 2 vectors draw them in a 2d vector space to see the local 1 and 2 vectors. the 3 dirn for the element is the cross product. (along z axis)

you have 2 vectors {9144 3962 0} and {-3962 9144 0}. Taking the cross product results in a 3'rd vector. The 1'st vector and 3'rd vecor are 1 and 3 directions. The 2 vector is in the 1-2 plane given by the second vector.

[wuhaoshrek]

fmk wrote:
> as for the 1 1 0 and -1 1 0 .. they are 2 vectors draw them in a 2d vector
> space to see the local 1 and 2 vectors. the 3 dirn for the element is the
> cross product. (along z axis)
>
> you have 2 vectors {9144 3962 0} and {-3962 9144 0}. Taking the cross
> product results in a 3'rd vector. The 1'st vector and 3'rd vecor are 1 and
> 3 directions. The 2 vector is in the 1-2 plane given by the second vector.

Dear fmk,
I have two zerolength element connecting two nodes 1 and 101. zeroLengthSection element 100 (using fiber section) to model RC column bar-slip effect
and zeroLength element 200 modeling shear behavior. Both of them have its local x in Global Y and local y in Global -X. here is the script:

element zeroLengthSection 100 1 101 $IDColSec_zeroBSSec -orient 0 1 0 -1 0 0 -doRayleigh 0 ;
element zeroLength 200 1 101 -mat $IDShearMat -dir 2 -doRayleigh 0 -orient 0 1 0 -1 0 0 ;

So why in this case it's not working in opensees it has the warning:

WARNING BandGenLinLapackSolver::solve() -LAPACK routine returned 4
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

Thankyouooo!

Hi fmk
I found the problem is I used tansformation constraint, when I use penalty it is running fine? I have equalDOF in my model,
so do you think that would be the reason? thx

[fmk]

no that should not be the solution .. if solver could solved system exactly, i.e. without numerical roundoff, the Penalty would probably fail to or else maybe the Transformation would work .. try a ProfileSPD solver or something else (one that does not use pivoting)

[idkopensees]

sir i think i have a problem in understanding this element.what will happen if i put this into script,does this(-orient -0.640 0.000 0.768) mean the local
ocal z-axis?will this two elements rotate about local z aixs?
element twoNodeLink 2 2 4 -mat 8 -dir 6 -orient -0.640 0.000 0.768
element zeroLength 5 1 5 -mat 2 -dir 6 -orient 0.000 0.000 1.000

[mhscott]

The -orient option is for specifying the local x and y axes
https://opensees.berkeley.edu/wiki/inde ... th_Element

[idkopensees]

The -orient option is for specifying the local x and y axes
https://opensees.berkeley.edu/wiki/inde ... th_Element

Sir,I specify local x and y axes,and now i ran into a new problem.The opensees says :"WARNING no -dirn flag encountered - element ZeroLength eleTag? iNode? jNode? -mat matID1? ... -dir dirMat1? .. <-orient x1? x2? x3? y1? y2? y3?>",my script is like this "element zeroLength 7 6 2 -mat 2 -dir 6 -orient -1 0 0 0 0 1
element zeroLength 8 3 7 -mat 2 -dir 6 -orient 0 0 1 1 0 0".I searched this and i dont know where is wrong.Sir could you help me ?