The OpenSees Community

Problem solved. Download the 32-bit version of Tcl/Tk executable.

Problem solved, my model had massless DOF.

When working with Central Difference, all DOF must have mass for the scheme to work.

I wonder if you could overcome this by condensing out the massless DOF? Any thoughts?

Maikol

Hi fmk,

I followed the input file you posted with explicit integrators. I followed it to construct my model with Central Difference but I still cannot get opensees to run it. The problem is the linear solver. Below is my input file, could please take a look at it?
Any help would be appreciated, Thanks
#####################################

# 3 m 4
# [+]-------------------------[+] -> dof1 (disp)
# o rigid beam o
# ¦ ¦ o : pin
# ¦ ¦ [+] : node
# ¦ ¦ @ : rotational spring
# 2 ¦ 5 ¦
# [+] dof2 (rot) [+] dof3 (rot)
# 1 @ 6 @
# ---[+]--- ---[+]---
# /////// ///////

wipe all;

# variable definition
set dt 0.01; # time step for analysis
set g 386.4; # acceleration of gravity
set m [expr 20/$g]; # mass, 20 kips /g

# model Command
model BasicBuilder -ndm 2 -ndf 3; # define the model builder, ndm = #dimension, ndf = #dofs
file mkdir Results; # create output folder

node 1 0 0;
node 2 0 0;
node 3 0 42 -mass [expr $m/2] 0 0;
node 4 42 42 -mass [expr $m/2] 0 0;
node 5 42 0;
node 6 42 0;

fix 1 1 1 1;
fix 6 1 1 1;

equalDOF 3 4 1; # diaphragm (roof)
equalDOF 1 2 1 2; # constrain displacement of rotational spring (left)
equalDOF 6 5 1 2; # constrain displacement of rotational spring (right)

geomTransf Linear 1; # Linear transformation

uniaxialMaterial Steel01 1 6000 26087 0.01; # bilinear model
uniaxialMaterial Steel01 2 60 26087 0.01; # bilinear model

element elasticBeamColumn 1 2 3 1000 29000 11.3 1; # left column
element elasticBeamColumn 2 5 4 1000 29000 11.3 1; # right column
element zeroLength 3 1 2 -mat 1 -dir 6; # rotational spring (left)
element zeroLength 4 6 5 -mat 2 -dir 6; # rotational spring (right)

recorder Node -file Results/Displacement.out -node 3 -dof 1 disp; # displacement

set duration 31.18; # duration of ground motion in seconds
set groundmotion "Path -filePath EL_Centro.txt -dt 0.02 -factor $g"

pattern UniformExcitation 1 1 -accel $groundmotion
numberer RCM # renumber dof's to minimize band-width (optimization)
constraints Transformation
system Diagonal
integrator CentralDifferenceNoDamping
algorithm Linear
analysis Transient

# perform the transient analysis
set no_steps [expr round($duration/$dt)+1];
analyze $no_steps $dt

wipe all;

Hi,

You can download the Tcl/Tk executable from http://www.activestate.com/activetcl/downloads.

But still, I cannot get Opensees to run. I get the following message: The application was unable to start correctly (0xc000007b). Could anyone help me with this?

Maikol

Hi,

I've got Windows 7 in my desktop and cannot download the Tcl/Tk executable from http://downloads.activestate.com/Active ... readed.exe
I got the following message: "Unable to download ...93667-win32-ix86-threaded.exe from downloads.activestate.com. Unable to open this internet site. The requested site is either unavailable or cannot be found. Please try again later."
Could Windows 7 be the problem? I used to be able to download it using Windows XP.

Maikol