SSI Problem - Error message

[mugekuleli]

Hi,

I recently started to use OpenSees soil materials. I'm trying to model a very simple SSI problem between a wall and soil. I followed the steps explained in "Excavation Supported by Cantilevered Sheet Pile Wall". As a result I was able to complete gravity analysis with "InitialStateWrapper" successfully. Then I tried to conduct gravity analysis. I keep getting the following error message:

"ProfileSPDLinDirectSolver::solve() - aii < 0 (i,aii):(0,0)
WARNING NewtonRaphson::solveCurrentStep() -theLinearSysOfEqn failed in solve ()
DirectIntegrationAnalysis::analyze() -the Algorithm failed at time 1
Opensees > anaylze failed, returned: -3 error flag"

I searched the forum. Apparently this means there is an error in the model, most probably due to material definition or boundary conditions. I checked everything several times, however I couldn't find the source of this error. I would appreciate if someone could help me on this issue. The following is the simplified input file:

wipe

#-----------------------------------------------------------------------------------------
# 1. CREATE SOIL NODES AND FIXITIES
#-----------------------------------------------------------------------------------------
model BasicBuilder -ndm 2 -ndf 2
source DisplayModel2D.tcl; # procedure for displaying a 2D perspective of model
source DisplayPlane.tcl; # procedure for displaying a plane in the model

# define soil nodes

node 72 -0.530769231 0
node 73 -0.530769231 0.426
node 79 -0.1 0
node 80 -0.1 0.426

puts "Finished creating all -ndf 3 soil nodes..."

# define fixities for soil nodes

fix 72 1 1
fix 73 1 0
fix 79 0 1

puts "Finished creating all -ndf 2 boundary conditions..."

#-----------------------------------------------------------------------------------------
# 2. DESIGNATE LIST OF SOIL NODES FOR RECORDERS
#-----------------------------------------------------------------------------------------

set sNodeInfo [open SoilNodesInfo.dat w]
puts $sNodeInfo " 72 -0.530769231 0"
puts $sNodeInfo " 73 -0.530769231 0.426"
puts $sNodeInfo " 79 -0.1 0"
puts $sNodeInfo " 80 -0.1 0.426"
close $sNodeInfo

#-----------------------------------------------------------------------------------------
# 3. CREATE LAGRANGE MULTIPLIER NODES FOR BEAM CONTACT ELEMENTS
#-----------------------------------------------------------------------------------------

for {set k 1} {$k <= 2} {incr k 1} {
node [expr 1000+$k] 0.00 0.00
}
puts "Finished creating all -ndf 2 nodes..."


#-----------------------------------------------------------------------------------------
# 4. CREATE SOIL MATERIALS
#-----------------------------------------------------------------------------------------

# define pressure depended material for soil (!!!!!)
#nDMaterial PressureDependMultiYield $tag $nd $rho $refShearModul $refBulkModul $frictionAng $peakShearStra $refPress $pressDependCoe $PTAng $contrac $dilat1 $dilat2
#$liquefac1 $liquefac2 $liquefac3 <$noYieldSurf=20 <$r1 $Gs1 …> $e=0.6 $cs1=0.9 $cs2=0.02 $cs3=0.7 $pa=101>
nDMaterial PressureDependMultiYield02 5 2 2.24 42735.4 128206.2 40 0.1 \
100.0 0.5 26 0.013 0.0 0.3 \
0.0 30 5.0 3.0 1.0 \
0.0 0.532 0.9 0.02 0.7 101.0

# element thickness
set thick1 2.74
# body force in x-direction
set xWgt1 0.00
# body force in y-direction
set yWgt1 [expr -9.81*2.1]

puts "Finished creating all soil materials..."

#-----------------------------------------------------------------------------------------
# 5. CREATE SOIL ELEMENTS
#-----------------------------------------------------------------------------------------

element quad 1 72 79 80 73 $thick1 PlaneStrain 5 0.0 0.0 $xWgt1 $yWgt1


puts "Finished creating all soil elements..."

# create list of permanent elements with connectivities for post-processing
set eleFile [open SolidElementInfo.dat w]
puts $eleFile "1 72 79 80 73"
close $eleFile

puts "Finished creating equalDOF for base..."


#-----------------------------------------------------------------------------------------
# 6. CREATE BEAM NODES AND FIXITIES
#-----------------------------------------------------------------------------------------
model BasicBuilder -ndm 2 -ndf 3

# define beam nodes
node 82 0.0 -0.213
node 83 0.0 0.213
node 85 0.0 0.639

puts "Finished creating all -ndf 3 beam nodes..."

# create list of beam nodes and locations for post-processing
set bNodeInfo [open NodesInfo3.dat w]

puts $bNodeInfo "82 0.0 -0.213"
puts $bNodeInfo "83 0.0 0.213"
puts $bNodeInfo "85 0.0 0.639"
close $bNodeInfo

# fix the top node of the wall in the vertial direction
fix 85 0 1 0

puts "Finished creating all -ndf 3 boundary conditions..."

#-----------------------------------------------------------------------------------------
# 7. CREATE BEAM MATERIALS
#-----------------------------------------------------------------------------------------

# beam properties
set thick 0.2
set area 0.2
set I 9.75e-4
set beamE 30000
set numIntPts 3
set transTag 1
set secTag 1

# geometric transformation
geomTransf Linear $transTag

# beam section
section Elastic $secTag $beamE $area $I

puts "Finished creating all beam materials..."

#-----------------------------------------------------------------------------------------
# 8. CREATE BEAM ELEMENTS
#-----------------------------------------------------------------------------------------

element dispBeamColumn 66 83 82 $numIntPts $secTag $transTag
element dispBeamColumn 67 85 83 $numIntPts $secTag $transTag
puts "Finished creating all beam elements..."

# create list of beam elements with connectivities for post-processing
set beamInfo [open beamElementInfo.dat w]
puts $beamInfo " 66 83 82"
puts $beamInfo " 67 85 83"
close $beamInfo

#-----------------------------------------------------------------------------------------
# 9. CREATE CONTACT MATERIAL FOR BEAM CONTACT ELEMENTS
#-----------------------------------------------------------------------------------------

# two-dimensional contact material
nDMaterial ContactMaterial2D 3 0.2 1000.0 0.0 0.0

puts "Finished creating all contact materials..."

#-----------------------------------------------------------------------------------------
# 10. CREATE BEAM CONTACT ELEMENTS
#-----------------------------------------------------------------------------------------

# set gap and force tolerances for beam contact elements
set gapTol 1.0e-4
set forceTol 1.0e-4

# define beam contact elements
element BeamContact2D 1001 83 82 79 1001 3 $thick $gapTol $forceTol
element BeamContact2D 1002 85 83 80 1002 3 $thick $gapTol $forceTol

# display the model with the node numbers
DisplayModel2D NodeNumbers

#-----------------------------------------------------------------------------------------
# 10. GRAVITY ANALYSIS
#-----------------------------------------------------------------------------------------

# Newmark parameters
set gamma 0.5
set beta 0.25
updateMaterialStage -material 5 -stage 0
constraints Transformation
test NormDispIncr 1e-5 30 1
algorithm Newton
numberer RCM
system ProfileSPD
integrator Newmark $gamma $beta
analysis Transient

analyze 10 500

puts "Finished with elastic gravity analysis..."