zerolength

[engnomran]

Hello every body
I model one concrete frame with two isolators.
Two columns and one beam and two isolators being under the beam and top of columns.
Top of each columns being one isolator.
I model two isolators with zerolenght commend.
Beam is elastic and columns model with fiber commend and they are nonlinear elements.
My commends are :

#============isolators===========================================================================
# VERTICAL
uniaxialMaterial Elastic 10 3044482758.62

# HORIZENTAL
#uniaxialMaterial Steel02 11 400e6 2e11 0.01 15 .925 .15
set moo 0.3
set mass 15828.75
set fy [expr $moo*$mass*$g]
# fy kinit b
uniaxialMaterial Steel01 11 $fy 2207250 0.

#ROTATION
uniaxialMaterial Elastic 12 0.

element zeroLength 3 3 4 -mat 10 10 11 12 12 12 -dir 1 2 3 4 5 6
element zeroLength 8 8 9 -mat 10 10 11 12 12 12 -dir 1 2 3 4 5 6

###############################################################################
# STATIC ANALYSIS #
###############################################################################


# ------------------------------
# Start of analysis generation
# ------------------------------
# Create the system of equation
system UmfPack
# Create the DOF numberer
numberer Plain
# Create the constraint handler
constraints Plain
# Create the convergence test
test NormDispIncr 1.0e-12 30
# Create the integration scheme
integrator LoadControl 0.01
# Create the solution algorithm
algorithm Newton
# Create the analysis object
analysis Static
# ------------------------------
# End of analysis generation
# ------------------------------
# ------------------------------
# Perform the gravity analysis
# ------------------------------
analyze 100
puts "\nGravity load analysis completed";


And but my questions :
1) Program after static analysis take a mistake due to I send link of picture error for you.
LINK OF ERROR:
http://upload7.ir/imgs/2014-10/50584152931418919822.png

2)Should stiffness of ROTATION being too much or zero?Why?


thanks a lot.

S.Amirhossein.M

[kavir]

Hi
How can I record plastic rotation of rotational spring (zero length element)?

[2015James]

your materaial uniaxialMaterial Elastic 12 0. which means there is no restrains at the direction. so the matrix is singular. you can try a proper value for the rotation matrerial or you can set a very big value. Have a try and good lucn.