convergence problem in pushover analysis

foadEng · Post by **foadEng** » Tue Apr 13, 2010 3:23 am

Hi
I am modeling a six story building and I want to perform some pushover analyses. But while doing the pushover analysis, I faced these errors :
WARNING - ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element: 60100(dW: (( 4.76821e-012, dW0: 6.06719e+028)
WARNING - ForceBeamColumn3d::update - failed to get compatible element forces & deformations for element: 60101(dW: (( 4.26129e-010, dW0: 6.06719e+028)
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.
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I faced these errors for most of my elements. I also should say that I tried the same algorithm for a 2 story 3d building and it worked properly but for this model (6 story and 3D) it didn't work out.
I think my modeling is correct and probably there is something wrong in analysis part of the algorithm but I couldn't find the problem until now. I really appreciate if anybody could help me to solve this.
Thank you very much!

Post by **fmk** » Tue Apr 13, 2010 3:02 pm

the step size is probably way too large .. dw0 is the energy unbalance in element at first step (it is huge e0+28, the element iterates down to an unbalance of 1e-12) which is good but does not meet the min tolerance built in.

if it works in 2d and not 3d check your section definitions.

foadEng · Post by **foadEng** » Tue Apr 13, 2010 9:28 pm

Thank you for your reply. I made my step size smaller but the problem still exists!! (First my step size was 0.001 and I made it 0.0001 but ...). As I told you before, this algorithm worked for a 3D smaller structure (2 story building) but for 6 story this problem exists.
I think my section definition is right but could you do me a favor and take a look at this part of my algorithm. Here is the script :

# Define SECTIONS -----------------------------------------------------------------------------------------------------------------------------
#SectionType: FiberSection

set in 1.0;

# define section tags:
set Col12SecTag 1
set Col34SecTag 2
set Col56SecTag 3
set Beam1SecTag 4
set Beam2SecTag 5
set Beam3SecTag 6
set Beam5SecTag 7
set Gird1SecTag 8
set Gird2SecTag 9
set Gird3SecTag 10
set Gird5SecTag 11
set ColSecTagFiber12 12
set ColSecTagFiber34 13
set ColSecTagFiber56 14
set BeamSecTagFiber1 15
set BeamSecTagFiber2 16
set BeamSecTagFiber3 17
set BeamSecTagFiber5 18
set GirdSecTagFiber1 19
set GirdSecTagFiber2 20
set GirdSecTagFiber3 21
set GirdSecTagFiber5 22
set SecTagTorsion 70

# define MATERIAL properties
set Fy [expr 44.0*$ksi]
set Es [expr 29000*$ksi]; # Steel Young's Modulus
set nu 0.3;
set Gs [expr $Es/2./[expr 1+$nu]]; # Torsional stiffness Modulus
set Hiso 0
set Hkin 1000
set matIDhard 1
uniaxialMaterial Hardening $matIDhard $Es $Fy $Hiso $Hkin

# ELEMENT properties
# Structural-Steel W-section properties
# column sections: W14x176 (first & second story columns)
set d [expr 15.22*$in]; # depth
set bf [expr 15.65*$in]; # flange width
set tf [expr 1.31*$in]; # flange thickness
set tw [expr 0.83*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $ColSecTagFiber12 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# column sections: W14x132 (third & forth story columns)
set d [expr 14.66*$in]; # depth
set bf [expr 14.725*$in]; # flange width
set tf [expr 1.030*$in]; # flange thickness
set tw [expr 0.645*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $ColSecTagFiber34 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# column sections: W14x90 (fifth and sixth story columns)
set d [expr 14.02*$in]; # depth
set bf [expr 14.52*$in]; # flange width
set tf [expr 0.71*$in]; # flange thickness
set tw [expr 0.44*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $ColSecTagFiber56 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# beam sections: W30x116 (first story)
set d [expr 30.01*$in]; # depth
set bf [expr 10.495*$in]; # flange width
set tf [expr 0.850*$in]; # flange thickness
set tw [expr 0.565*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $BeamSecTagFiber1 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# beam sections: W27x102 (second story)
set d [expr 27.09*$in]; # depth
set bf [expr 10.015*$in]; # flange width
set tf [expr 0.830*$in]; # flange thickness
set tw [expr 0.515*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $BeamSecTagFiber2 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# beam sections: W24x68 (third, forth & sixth story)
set d [expr 23.73*$in]; # depth
set bf [expr 8.965*$in]; # flange width
set tf [expr 0.585*$in]; # flange thickness
set tw [expr 0.415*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $BeamSecTagFiber3 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# beam sections: W24x84 (fifth story)
set d [expr 24.10*$in]; # depth
set bf [expr 9.020*$in]; # flange width
set tf [expr 0.770*$in]; # flange thickness
set tw [expr 0.470*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $BeamSecTagFiber5 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# girder sections: W30x116 (first story)
set d [expr 30.01*$in]; # depth
set bf [expr 10.495*$in]; # flange width
set tf [expr 0.850*$in]; # flange thickness
set tw [expr 0.565*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $GirdSecTagFiber1 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# girder sections: W27x102 (second story)
set d [expr 27.09*$in]; # depth
set bf [expr 10.015*$in]; # flange width
set tf [expr 0.830*$in]; # flange thickness
set tw [expr 0.515*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $GirdSecTagFiber2 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# girder sections: W24x68 (third, forth & sixth story)
set d [expr 23.73*$in]; # depth
set bf [expr 8.965*$in]; # flange width
set tf [expr 0.585*$in]; # flange thickness
set tw [expr 0.415*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $GirdSecTagFiber3 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf
# girder sections: W24x84 (fifth story)
set d [expr 24.10*$in]; # depth
set bf [expr 9.020*$in]; # flange width
set tf [expr 0.770*$in]; # flange thickness
set tw [expr 0.470*$in]; # web thickness
set nfdw 16; # number of fibers along dw
set nftw 2; # number of fibers along tw
set nfbf 16; # number of fibers along bf
set nftf 4; # number of fibers along tf
Wsection $GirdSecTagFiber5 $matIDhard $d $bf $tf $tw $nfdw $nftw $nfbf $nftf

# assign torsional Stiffness for 3D Model
uniaxialMaterial Elastic $SecTagTorsion $Ubig
section Aggregator $Col12SecTag $SecTagTorsion T -section $ColSecTagFiber12
section Aggregator $Col34SecTag $SecTagTorsion T -section $ColSecTagFiber34
section Aggregator $Col56SecTag $SecTagTorsion T -section $ColSecTagFiber56
section Aggregator $Beam1SecTag $SecTagTorsion T -section $BeamSecTagFiber1
section Aggregator $Beam2SecTag $SecTagTorsion T -section $BeamSecTagFiber2
section Aggregator $Beam3SecTag $SecTagTorsion T -section $BeamSecTagFiber3
section Aggregator $Beam5SecTag $SecTagTorsion T -section $BeamSecTagFiber5
section Aggregator $Gird1SecTag $SecTagTorsion T -section $GirdSecTagFiber1
section Aggregator $Gird2SecTag $SecTagTorsion T -section $GirdSecTagFiber2
section Aggregator $Gird3SecTag $SecTagTorsion T -section $GirdSecTagFiber3
section Aggregator $Gird5SecTag $SecTagTorsion T -section $GirdSecTagFiber5

*************************************************************
Y is vertical direction and beam and girder elements are in X and Z directions, respectively.

Thank you very much

foadEng · Post by **foadEng** » Fri Apr 16, 2010 9:41 pm

Hi all,
I still have the same problem and I couldn't solve it. I'll really appreciate if anyone could help me to solve this problem. I've posted the modeling part of my script. Can anybody find any problem in this script?

Thank you very much