Analysis failed

[Strep]

Dear all

i'm trying to analyze a 2D truss with 240 nodes and 711 elements. the material i use are concrete07 and steel02 for the truss elements.

when i'm trying to do a simple static analysis an error occurs:

WARNING BandSPDLinLapackSolver::solve() - the LAPACK routines returned 416
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
-3

above is the analysis part of my script:

# Gravity-analysis parameters -- load-controlled static analysis
set Tol 1.0e-8; # convergence tolerance for test
constraints Plain; # how it handles boundary conditions
numberer RCM; # renumber dof's to minimize band-width (optimization), if you want to
system BandSPD; # how to store and solve the system of equations in the analysis

test NormDispIncr $Tol 6 ; # determine if convergence has been achieved at the end of an iteration step
algorithm Newton; # use Newton's solution algorithm: updates tangent stiffness at every iteration
set NstepGravity 10; # apply gravity in 10 steps
set DGravity [expr 1./$NstepGravity]; # first load increment;
integrator LoadControl $DGravity; # determine the next time step for an analysis
analysis Static; # define type of analysis static or transient
set ok [analyze $NstepGravity]; # apply gravity


but when i run the analysis in only one step using the scipt from the examples:

system BandSPD
numberer RCM
constraints Plain
integrator LoadControl 1
algorithm Linear
analysis Static
analyze 1

i get no error....

what does this error mean and what i can do to solve it???


Thank you very much for your help

[fmk]

your matrix is singular, i.e. not enough constraints.