2D frame in 3D space

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mgs
Posts: 20
Joined: Sun Aug 11, 2013 11:11 pm
Location: Griffith University

2D frame in 3D space

Post by mgs »

Hi Frank,
I have a simple 2D frame (1 story 3 bays frame in inplane dir and cantilevered in outplane dir) and want to perform a bi-direction transient analysis in 3D space (i.e. model BasicBuilder -ndm 3 -ndf 6). But there seems to be a problem with the mass definition.

I tried with both nodal (lump) and distributed mass but it seems the mass matrix is not generated at all. when i perform eigenvalue analysis, i get the modal periods but nut the eigenvalues and then opensees stops working.

with the bi-directional transient dynamic, very little responses are recorded i.e. like the frame is rigid.

with static pushover. it works very well.

can you give me an idea what could be wrong?
mgs
Posts: 20
Joined: Sun Aug 11, 2013 11:11 pm
Location: Griffith University

Re: 2D frame in 3D space

Post by mgs »

Here is the model code:

#
model BasicBuilder -ndm 3 -ndf 6
####################################################
# NODES FOR PIER
####################################################
# Pier 1
# ID X Y Z
node 435 752 -28 -413
node 436 752 -28 -383.5
node 437 752 -28 -354
node 438 752 -28 -324.5
node 439 752 -28 -295
node 440 752 -28 -265.5
node 441 752 -28 -236
node 442 752 -28 -206.5
node 443 752 -28 -177
node 444 752 -28 -147.5
node 445 752 -28 -118
node 446 752 -28 -88.5
node 447 752 -28 -59
node 448 752 -28 -29.5
node 449 752 -28 0
node 450 752 -28 29.5
node 451 752 -28 59
node 452 752 -28 88.5
node 453 752 -28 118
node 454 752 -28 147.5
node 455 752 -28 177
node 456 752 -28 206.5
node 457 752 -28 236
node 458 752 -28 265.5
node 459 752 -28 295
node 460 752 -28 324.5
node 461 752 -28 354
node 462 752 -28 383.5
node 463 752 -28 413

node 464 752 -56 -354
node 474 752 -356 -354

node 475 752 -56 -118
node 485 752 -356 -118

node 486 752 -56 118
node 496 752 -356 118

node 497 752 -56 354
node 507 752 -356 354
############################################
# Boundary Condition
############################################
fixY -356 1 1 1 1 1 1
########################################################################
# mass
########################################################################
set ms 0.149674023
for {set i 435} {$i<=463} {incr i 1} {
mass $i $ms $ms $ms 0 0 0
}
#==========================================================================
# COLUMN & BENT CAP MATERIAL
#==========================================================================
set fc -4.64; # Unconfined concrete strength
set fys 58; # Reinforcing steel yield strength
set Es 29000.0; # Reinforcing steel Modulus of Elasticity
set Ec [expr 57.0*pow(-$fc*1000,0.5)]; # Concrete Modulus of elasticity
set Gc [expr $Ec/2.4]
# Estimate yield curvature
# (Assuming no axial load and only top and bottom steel)
set d 34.5 ;# d -- from cover to rebar
set epsy [expr $fys/$Es] ;# steel yield strain
set Ky [expr $epsy/(0.7*$d)]; # Yield Curvature
#
# Print estimate to standard output
puts "Estimated yield curvature: $Ky"
#
# CONCRETE tag f'c ec0 f'cu ecu
# Cover concrete (cover)
# core concrete (core)
uniaxialMaterial Concrete01 1 $fc -0.002 [expr 0.2*$fc] -0.004
#
#
uniaxialMaterial Concrete01 2 $fc -0.002 0 -0.004
#
# REINFORCING STEEL tag
uniaxialMaterial Steel01 3 $fys $Es 0.018
#
# Torsion Material
uniaxialMaterial Elastic 4 7e10
uniaxialMaterial Elastic 5 [expr $Gc*26*114]
########################################################################
# Headstock elements
########################################################################
set bWidth 40
set bDepth 60
#
set cover 2; # inches
set As1 0.311; # area of an arbitrary bar
set As2 1.246
# some variables derived from the parameters
set y1 [expr $bDepth/2.0]
set z1 [expr $bWidth/2.0]
#
#
section Fiber 3 {
#
# Create the concrete core fibers
patch quad 1 10 20 [expr $cover-$y1] [expr $cover-$z1] [expr $y1-$cover] [expr $cover-$z1] [expr $y1-$cover] [expr $z1-$cover] [expr $cover-$y1] [expr $z1-$cover]
#
# Create the concrete cover fibers (top, bottom, left, right)
patch quad 2 10 2 [expr -$y1] [expr $z1-$cover] $y1 [expr $z1-$cover] $y1 $z1 [expr -$y1] $z1
patch quad 2 10 2 [expr -$y1] [expr -$z1] $y1 [expr -$z1] $y1 [expr $cover-$z1] [expr -$y1] [expr $cover-$z1]
patch quad 2 2 20 [expr -$y1] [expr $cover-$z1] [expr $cover-$y1] [expr $cover-$z1] [expr $cover-$y1] [expr $z1-$cover] [expr -$y1] [expr $z1-$cover]
patch quad 2 2 20 [expr $y1-$cover] [expr $cover-$z1] $y1 [expr $cover-$z1] $y1 [expr $z1-$cover] [expr $y1-$cover] [expr $z1-$cover]
#
# Create the reinforcing fibers (right, middle, left)
layer straight 3 8 $As2 [expr $y1-$cover] [expr $z1-$cover] [expr $y1-$cover] [expr $cover-$z1]
layer straight 3 2 $As2 [expr $y1-$cover-18] [expr $z1-$cover] [expr $y1-$cover-18] [expr $cover-$z1]
layer straight 3 2 $As1 [expr $y1-$cover-9] [expr $z1-$cover] [expr $y1-$cover-9] [expr $cover-$z1]
layer straight 3 2 $As1 0 [expr $z1-$cover] 0 [expr $cover-$z1]
layer straight 3 2 $As1 [expr $cover-$y1+9] [expr $z1-$cover] [expr $cover-$y1+9] [expr $cover-$z1]
layer straight 3 2 $As1 [expr $cover-$y1+18] [expr $z1-$cover] [expr $cover-$y1+18] [expr $cover-$z1]
layer straight 3 8 $As2 [expr $cover-$y1] [expr $z1-$cover] [expr $cover-$y1] [expr $cover-$z1]
}
#
section Aggregator 4 4 T -section 3
#################################################
geomTransf PDelta 4 0 1 0
#
#
set int3 4 ; #integration point
############################################################
element dispBeamColumn 200 435 436 $int3 4 4
element dispBeamColumn 201 436 437 $int3 4 4
element dispBeamColumn 202 437 438 $int3 4 4
element dispBeamColumn 203 438 439 $int3 4 4
element dispBeamColumn 204 439 440 $int3 4 4
element dispBeamColumn 205 440 441 $int3 4 4
element dispBeamColumn 206 441 442 $int3 4 4
element dispBeamColumn 207 442 443 $int3 4 4
element dispBeamColumn 208 443 444 $int3 4 4
element dispBeamColumn 209 444 445 $int3 4 4
element dispBeamColumn 210 445 446 $int3 4 4
element dispBeamColumn 211 446 447 $int3 4 4
element dispBeamColumn 212 447 448 $int3 4 4
element dispBeamColumn 213 448 449 $int3 4 4
element dispBeamColumn 214 449 450 $int3 4 4
element dispBeamColumn 215 450 451 $int3 4 4
element dispBeamColumn 216 451 452 $int3 4 4
element dispBeamColumn 217 452 453 $int3 4 4
element dispBeamColumn 218 453 454 $int3 4 4
element dispBeamColumn 219 454 455 $int3 4 4
element dispBeamColumn 220 455 456 $int3 4 4
element dispBeamColumn 221 456 457 $int3 4 4
element dispBeamColumn 222 457 458 $int3 4 4
element dispBeamColumn 223 458 459 $int3 4 4
element dispBeamColumn 224 459 460 $int3 4 4
element dispBeamColumn 225 460 461 $int3 4 4
element dispBeamColumn 226 461 462 $int3 4 4
element dispBeamColumn 227 462 463 $int3 4 4
######################################################################
# pier material
######################################################################
set b 30; #Width
set d 118; #Depth
#
set cover 2; # in
#
set As3 .6; # ~ area of bar no. 28
#
# some variables derived from the parameters
set y1 [expr $b/2.0]
set z1 [expr $d/2.0]
#
#
section Fiber 1 {
#
# Create the concrete core fibers
patch quad 1 10 20 [expr $cover-$y1] [expr $cover-$z1] [expr $y1-$cover] [expr $cover-$z1] [expr $y1-$cover] [expr $z1-$cover] [expr $cover-$y1] [expr $z1-$cover]
#
# Create the concrete cover fibers (top, bottom, left, right)
patch quad 2 10 2 [expr -$y1] [expr $z1-$cover] $y1 [expr $z1-$cover] $y1 $z1 [expr -$y1] $z1
patch quad 2 10 2 [expr -$y1] [expr -$z1] $y1 [expr -$z1] $y1 [expr $cover-$z1] [expr -$y1] [expr $cover-$z1]
patch quad 2 2 20 [expr -$y1] [expr $cover-$z1] [expr $cover-$y1] [expr $cover-$z1] [expr $cover-$y1] [expr $z1-$cover] [expr -$y1] [expr $z1-$cover]
patch quad 2 2 20 [expr $y1-$cover] [expr $cover-$z1] $y1 [expr $cover-$z1] $y1 [expr $z1-$cover] [expr $y1-$cover] [expr $z1-$cover]
#
# Create the reinforcing fibers (right, middle, left)
layer straight 3 14 $As3 [expr $y1-$cover] [expr $z1-$cover] [expr $y1-$cover] [expr $cover-$z1]
layer straight 3 6 $As3 -13 [expr $z1-$cover] 13 [expr $z1-$cover]
layer straight 3 6 $As3 -13 [expr $cover-$z1] 13 [expr $cover-$z1]
layer straight 3 14 $As3 [expr $cover-$y1] [expr $z1-$cover] [expr $cover-$y1] [expr $cover-$z1]
}
# TAG Mat Dir section
section Aggregator 2 5 Vy 5 Vz 4 T -section 1
######################################################################
# pier elements
######################################################################
geomTransf PDelta 3 0 0 -1
#
#
set int 4; # integration poin
################################
element forceBeamColumn 300 464 474 3 "HingeRadau 2 17.22 2 34.02 2"
element forceBeamColumn 400 475 485 3 "HingeRadau 2 17.22 2 34.02 2"
element forceBeamColumn 500 486 496 3 "HingeRadau 2 17.22 2 34.02 2"
element forceBeamColumn 600 497 507 3 "HingeRadau 2 17.22 2 34.02 2"
##======================================================================================
# RIGID ELEMENTS
#======================================================================================
#
set Atd 1e8 ; # Cross-sectional Area in^2
set Itd 1e9 ; # Moment of Inertia in^4
set Etd 1e8 ; # Elastic Modulus ksi
set Gtd 1e8 ; # Modulus of Rigidity ksi
set Jtd 1e9 ; # Polar MOI in^4
#
#
#==========================================================================
# RIGID LINKS
#==========================================================================
#
# TAG Xv Yv Zv
geomTransf Linear 6 1 0 0
#
# Tag iN jN A E G J Iz Iy Transf
element elasticBeamColumn 9059 464 437 $Atd $Etd $Gtd $Jtd $Itd $Itd 6
element elasticBeamColumn 9060 475 445 $Atd $Etd $Gtd $Jtd $Itd $Itd 6
element elasticBeamColumn 9061 486 453 $Atd $Etd $Gtd $Jtd $Itd $Itd 6
element elasticBeamColumn 9062 497 461 $Atd $Etd $Gtd $Jtd $Itd $Itd 6
###############################################################################################################################################
# END OF MODEL GENERATION
##############################################################################################################################################
#
logFile pier.log
fmk
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Posts: 5884
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
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Re: 2D frame in 3D space

Post by fmk »

when i put the following at end of file i get stuff, both eigenvalues and eigenvector .. so not quite sure what your problem is:


puts [eigen 10]
puts [nodeEigenvector 463 1]
mgs
Posts: 20
Joined: Sun Aug 11, 2013 11:11 pm
Location: Griffith University

Re: 2D frame in 3D space

Post by mgs »

Hi Frank,
I appreciate your feedback. Could you please advise a relevant example, i.e. 2d structure in 3d space, so that I could compare my model. I did n't find any in OpenSees Wiki.

Regards,
mgs
Posts: 20
Joined: Sun Aug 11, 2013 11:11 pm
Location: Griffith University

Re: 2D frame in 3D space

Post by mgs »

Hi,
I added more nodes along the columns i.e. columns now consisted of 10 elements rather than 1 element which was before. This has solved the issue with the modal and transient analyses in which the mass matrices seem now generated with no problem. BUT, the static pushover is not working as before as the analysis diverge rapidly. Very weird situation.
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