proc MomentCurvature {secTag axialLoad maxK {numIncr 100} } {
# Define two nodes at (0,0)
node 1 0.0 0.0
node 2 0.0 0.0
# Fix all degrees of freedom except axial and bending
fix 1 1 1 1
fix 2 0 1 0
# Define element
# tag ndI ndJ secTag
element zeroLengthSection 1 1 2 $secTag
# Create recorder
recorder Node -file section$secTag.out -time -node 2 -dof 3 disp
recorder Element -file Element1.out -time -ele 1 2 section 1 fiber 5.68 4.8 stressStrain
# Define constant axial load
pattern Plain 1 "Constant" {
load 2 $axialLoad 0.0 0.0
}
# Define analysis parameters
integrator LoadControl 0.0
system SparseGeneral -piv; # Overkill, but may need the pivoting!
test NormUnbalance 1.0e-2 10
numberer Plain
constraints Plain
algorithm Newton
analysis Static
# Do one analysis for constant axial load
analyze 1
# Define reference moment
pattern Plain 2 "Linear" {
load 2 0.0 0.0 1.0
}
# Compute curvature increment
set dK [expr $maxK/$numIncr]
# Use displacement control at node 2 for section analysis
integrator DisplacementControl 2 3 $dK 1 $dK $dK
# Do the section analysis
analyze $numIncr
}
# Define model builder
# --------------------
model basic -ndm 2 -ndf 3
# Define materials for nonlinear columns
# ------------------------------------------
uniaxialMaterial Concrete02 1 -37597.5 -0.0055 -7519.5 -0.0161 0.1 3759.7 1319350
uniaxialMaterial Concrete02 2 -37597.5 -0.0055 -7519.5 -0.0137 0.1 3759.7 1319350
uniaxialMaterial Steel02 3 335000 200000000 0.01 18 0.925 0.15
puts "section"
section Fiber 1 {
patch rect 1 15 1 -6.5 4.8 6.5 6
patch rect 1 15 1 -6.5 -6 6.5 -4.8
patch rect 1 1 8 -6.5 -4.8 -5.6 4.8
patch rect 1 1 8 -0.3 -4.8 0.3 4.8
patch rect 1 1 8 5.6 -4.8 6.5 4.8
layer straight 3 132 0.000615 -6.45 5.95 6.45 5.95
layer straight 3 132 0.000615 -6.45 4.85 6.45 4.85
layer straight 3 132 0.000615 -6.45 -4.85 6.45 -4.85
layer straight 3 132 0.000615 -6.45 -5.95 6.45 -5.95
layer straight 3 120 0.000615 -6.45 5.95 -6.45 -5.95
layer straight 3 120 0.000615 -5.65 5.95 -5.65 -5.95
layer straight 3 120 0.000615 -0.25 5.95 -0.25 -5.95
layer straight 3 120 0.000615 0.25 5.95 0.25 -5.95
layer straight 3 120 0.000615 5.65 5.95 5.65 -5.95
layer straight 3 120 0.000615 6.45 5.95 6.45 -5.95
}
# Estimate yield curvature
# (Assuming no axial load and only top and bottom steel)
set d 12.975
set epsy 0.001675
set Ky 1.8442058904486650151390035783099e-4
# Print estimate to standard output
puts "Estimated yield curvature: $Ky"
# Set axial load
set P -450000
set mu 8; # Target ductility for analysis
set numIncr 100; # Number of analysis increments
# Call the section analysis procedure
MomentCurvature 1 $P [expr $Ky*$mu] $numIncr
This output command：
recorder Element -file Element1.out -time -ele 1 2 section 1 fiber 5.68 4.8 stressStrain
Unable to output the specified fiber stress and strain
Ask everybody to help see be what reason
