error: sectionAggregator::getsectionFlexibility--singular...

[zareian1]

hi all.
I've modeled a 3-bay 4-story RC moment frame and subjected it to an earthquake record. I've used element type forceBeamColumn and fiber section, my model is without any error or warning, but When i add shear to fiber section with section Aggregator, I've found some error message.
The error is: "sectionAggregator::getsectionFlexibility--singular section stiffness".
can anyone tell why the error is ?????????..............

[vesna]

You may be having an error in definition of your section aggregator. If you post the relevant part of your code where you define your section I can check it out.

[zareian1]

Dear Vesna Thank you so much for your attention,
it is the relevant part of my code where i define my section

# units : kN , m , s

#proc BuildRCSection {id HSec BSec coverH coverB coreID coverID steelID numBarsTop barAreaTop numBarsBot barAreaBot numBarsIntTot barAreaInt Sstirrup nfCoreY #nfCoreZ nfCoverY nfCoverZ} {

# Formal arguments
# id - tag for the section that is generated by this procedure
# HSec - depth of section, along local-y axis
# BSec - width of section, along local-z axis
# coverH - distance from section boundary to neutral axis of reinforcement
# coverB - distance from section boundary to side of reinforcement
# coreID - material tag for the core patch
# coverID - material tag for the cover patches
# steelID - material tag for the reinforcing steel
# numBarsTop - number of reinforcing bars in the top layer
# numBarsBot - number of reinforcing bars in the bottom layer
# numBarsIntTot - TOTAL number of reinforcing bars on the intermediate layers, symmetric about z axis and 2 bars per layer-- needs to be an even integer
# barAreaTop - cross-sectional area of each reinforcing bar in top layer
# barAreaBot - cross-sectional area of each reinforcing bar in bottom layer
# barAreaInt - cross-sectional area of each reinforcing bar in intermediate layer
# Sstirrup - spacing of transverse reinforcement
# nfCoreY - number of fibers in the core patch in the y direction
# nfCoreZ - number of fibers in the core patch in the z direction
# nfCoverY - number of fibers in the cover patches with long sides in the y direction
# nfCoverZ - number of fibers in the cover patches with long sides in the z direction

BuildRCSection 21 0.45 0.40 0.05 0.05 1 2 3 6 3.8013e-4 4 3.1416e-4 0 0 0.20 20 20 20 20;
section Aggregator 41 221 Vy -section 21

[vesna]

Your section definition looks good to me. However EPP material that you use to define shear may cause problems. I am assuming that as a solver you use BandGeneral.

Try defining your shear with Steel01 and assign to b very small number (e.g., 1.0e-15).