T section

[Ahm]

Hi all.........
I used 2 type of section Rect-section & T-section with the same depth .
when carrying out MomentCurvature such as example2.1 ,I get the same result for the 2 sections...............................
I think the problem is OS working with only one value of width........
please help me.................................................

[silvia]

please post/send the scripts.

[Ahm]

Hi Silvia............
first I will put the case of T-section

# Define model builder of T-section
# --------------------
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 26

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]
patch rect 1 1 5 [expr $y1-6] $z1 $y1 [expr $z1+16]
patch rect 1 1 5 [expr $y1-6] [expr -$z1] $y1 [expr -$z1-16]



# 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]
layer straight 3 4 $As [expr $y1-$cover] [expr $z1+14] [expr $y1-$cover] [expr -$z1-14]
}

# 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
##------------------------------------------------
##----------------------------------------------



Then the case of Rect-section

# 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 26

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 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]
layer straight 3 4 $As [expr $y1-$cover] [expr $z1+14] [expr $y1-$cover] [expr -$z1-14]
}

# 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
##-----------------------------------------------------------
##-------------------------------------------------------------

I know that there is may be error due to the position of steel inthe Rect-section , but what I want to say that there is no change when add the fibers which represent the top flang of the T-section
Is OS can go with section with 2 values of width?..................

Thanks alot.

[silvia]

you should not use the rect patch, as it is undocumented (where did you find documentation on it?)

try using the quad patch, and

please let me know if this works.

[Ahm]

Thanks Silvia for your friendly help..........................
I use rect path as in Example3.1
I will use quad patch & see the result
Thanks alot...........................

[silvia]

the quad patch is more versatile.
please let me know how it goes.
s-