# Define model builder
# --------------------
model basic -ndm 2 -ndf 3
# Define materials for nonlinear columns
# ------------------------------------------
# CONCRETE tag f'c ec0 f'cu ecu
# Core concrete (confined)
uniaxialMaterial Concrete01 1 -6.0 -0.004 -5.0 -0.014
# Cover concrete (unconfined)
uniaxialMaterial Concrete01 2 -5.0 -0.002 0.0 -0.006
# STEEL
# Reinforcing steel
set fy 60.0; # Yield stress
set E 30000.0; # Young's modulus
# tag fy E0 b
uniaxialMaterial Steel01 3 $fy $E 0.01
# Define cross-section for nonlinear columns
# ------------------------------------------
# set some paramaters
set colWidth 15
set colDepth 24
set cover 1.5
set As 0.60; # area of no. 7 bars
# some variables derived from the parameters
set y1 [expr $colDepth/2.0]
set z1 [expr $colWidth/2.0]
section Fiber 1 {
# Create the concrete core fibers
patch rect 1 10 1 [expr $cover-$y1] [expr $cover-$z1] [expr $y1-$cover] [expr $z1-$cover]
# Create the concrete cover fibers (top, bottom, left, right)
patch rect 2 10 1 [expr -$y1] [expr $z1-$cover] $y1 $z1
patch rect 2 10 1 [expr -$y1] [expr -$z1] $y1 [expr $cover-$z1]
patch rect 2 2 1 [expr -$y1] [expr $cover-$z1] [expr $cover-$y1] [expr $z1-$cover]
patch rect 2 2 1 [expr $y1-$cover] [expr $cover-$z1] $y1 [expr $z1-$cover]
# Create the reinforcing fibers (left, middle, right)
layer straight 3 3 $As [expr $y1-$cover] [expr $z1-$cover] [expr $y1-$cover] [expr $cover-$z1]
layer straight 3 2 $As 0.0 [expr $z1-$cover] 0.0 [expr $cover-$z1]
layer straight 3 3 $As [expr $cover-$y1] [expr $z1-$cover] [expr $cover-$y1] [expr $cover-$z1]
}
# Estimate yield curvature
# (Assuming no axial load and only top and bottom steel)
set d [expr $colDepth-$cover] ;# d -- from cover to rebar
set epsy [expr $fy/$E] ;# steel yield strain
set Ky [expr $epsy/(0.7*$d)]
# Print estimate to standard output
puts "Estimated yield curvature: $Ky"
# Set axial load
set P -180
set mu 15; # Target ductility for analysis
set numIncr 100; # Number of analysis increments
# Call the section analysis procedure
source MomentCurvature.tcl
MomentCurvature 1 $P [expr $Ky*$mu] $numIncr
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