Why my dynamic analysis does not continue until degradation?

[ismailqeshta]

Hi,

I am trying to perform a dynamic analysis for a single nonlinear column using the code below. The problem is that when I plot the load-deformation, it shows only two cycles and the column does not show a degradation in the capacity.

# Load pattern
set H 148000.0

# Define lareral load pattern
# timeSeries Constant 2

set tag 2
set tStart 0.0
set tEnd 12.0
set period 6.0

timeSeries Trig $tag $tStart $tEnd $period
pattern Plain 2 2 {
# Node MX MY MZ
foreach node {225} {
load $node $H 0.0 0.0
}
}

#
# Add mass proportional damping
set zdamp 0.05; #damping ratio
set Bdamp [expr 2.0*$zdamp*$omega]; # Rayleigh damping factor
rayleigh $Bdamp 0 0 0;

# ------------------------------
# Start of analysis generation
# ------------------------------
# create the system of equations
system BandGeneral
# create the DOF numberer
numberer RCM
# create the constraint handler
constraints Transformation
# create the convergence test
test EnergyIncr 1.0e-6 400
# create the integration scheme
integrator Newmark 0.5 0.25
#integrator NewmarkExplicit 0.5
#integrator AlphaOS 1.0
# create the solution algorithm
#algorithm Linear
algorithm Newton
# create the analysis object
analysis Transient
# ------------------------------
# End of analysis generation
# ------------------------------

set dt_analysis 0.01;
set Mtime 200.0; # timestep of analysis
set NumSteps [expr round($Mtime/$dt_analysis)]; # number of steps in analysis

puts "\nPushing.."

for {set i 1} {$i < $NumSteps} {incr i} {

set ok [analyze 1 $dt_analysis]

puts "step $i out of $NumSteps"
}

wipe
exit



It would be great if someone can guide me in resolving this.

Thank you very much.

[Jhno]

I don't know for your main problem, but there is a little error in your for loop
for {set i 1} {$i < $NumSteps} {incr i} {

set ok [analyze 1 $dt_analysis]

puts "step $i out of $NumSteps"
}
Should write
for {set i 1} {$i < $NumSteps} {incr i 1} {

set ok [analyze 1 $dt_analysis]

puts "step $i out of $NumSteps"
}

[ismailqeshta]

Thanks for your reply. But I cannot see any error. Both code lines are the same!

[Jhno]

"Both code lines are the same!"
Take a closer look, there is 1 difference.

[rafal]

Jhno,
According to the documentation of tcl
http://wiki.tcl.tk/1476
by default the optional parameter ?increment? is equal to 1, so
"incr i 1" is eqivalent to "incr i"

[Jhno]

Oh, then I was wrong. Did not know of this!