Dear all,

I modeled a cantilever column with a concentrated mass at its top as 2dof structure. Picture below shows schematic of structure:

The code to model the system is as follow:

#to model a cantilever steel column

#units [length: cm], [force: kgf]

wipe

source box.txt; #procedure to model steel box sections

model BasicBuilder -ndm 3 -ndf 6

node 1 0 0 0

node 2 0 300 0

fix 1 1 1 1 1 1 1

fix 2 0 0 0 0 0 0

mass 2 20 1e-9 20 0 0 0; #assign seismic mass to dof’s 1 & 2

set matID 1

uniaxialMaterial Steel01 $matID 2400 2.1E6 0.02

set coltag 1

box $coltag $matID 20 1; #steel box section of width 20cm and thickness 1cm

geomTransf PDelta 1 0 0 1

element nonlinearBeamColumn 1 1 2 5 1 1

eigen 2; #calculate eigenvalues

I am trying to calculate 2 eigenvalues but I faced to this error:

ArpackSolver::Error with _saupd info = -9999

Could not build an Arnoldi factorization.IPARAM(5) the size of the current Arnoldi factorization: is 3factorization. The user is advised to check thatenough workspace and array storage has been allocated.

WARNING DirectIntegrationAnalysis::eigen() – EigenSOE failed in solve()

Do you know where the problem is?

I would appreciate it if you give consideration to this request.