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# femamomentrotation.tcl
#
# Procedure which creates a uniaxial material to be used in defining 
# moment-rotation curves in FEMA-273 for pushover analysis.
#
# Written: BT
# Date: Dec 2002
#
# Formal arguments
#    eleID - unique uniaxial material ID for this material
#    E     - rotational stiffness (My/EI)
#    My    - yield moment
#    h     - % hardening
#    c,d,e - FEMA values (see figure below)
#    index - defines the dummy material tags
#
#          Q/Qce
#            ^
#            |<-------------- e ------->
#            |<------ d ------>
#            |       __________
#            |      /          |
#            |     /           |
#            |    /            |
#            |   /             |
#            |  /              |_______    ^
#            | /                        |  c            
#            |/                         |  v
#            L-------------------------------> rot/roty
#
#            Q    - generalized component load
#            Qce  - generalized component expected strength
#            rot  - plastic rotation of beam or column
#            roty - rotation at yield
#
# Returns
#    Nothing
#
# Notes
#    - Won't work in OpenSees versions > 1.3

proc FEMAMomentRotation {eleID E My h c d e} {

    # calculate internal values
    set M1   [expr (1-$c)*$My];
    set M2   [expr $c*$My];
    set roty [expr $My/$E];
    set k1   [expr $M1/$roty];
    set k2   [expr $M2/$roty];
    
    # define uniaxial materials
    #                           tag                 E     fy  h_iso               h_kin
    uniaxialMaterial Hardening  [expr $eleID*100+1] $k1   $M1 [expr $h*($k1+$k2)] 0.0
    uniaxialMaterial Hardening  [expr $eleID*100+2] $k2   $M2 0.001               0.0
    uniaxialMaterial Elastic    [expr $eleID*100+3] 1e-5

    # combine in parallel
    #                           tag                 tag1                tag2                max			    min
    uniaxialMaterial Parallel   [expr $eleID*100+4] [expr $eleID*100+1] [expr $eleID*100+3] -max [expr $roty * $d] -min [expr -1* $roty * $d];
    uniaxialMaterial Parallel   [expr $eleID*100+5] [expr $eleID*100+2] [expr $eleID*100+4] -max [expr $roty * $e] -min [expr -1* $roty * $e];
    uniaxialMaterial Parallel   $eleID              [expr $eleID*100+5] [expr $eleID*100+3]
}

Code: Select all

# set time step
set timeStep 0.02

# total groundmotion time
set tGm 60.0; # seconds

# get the pseudo time
set tCurrent [getTime]

# set parameter to check if analysis is converged or not
set analysisConverged 0;
	
# Perform the transient analysis till the end of the ground motion
# or convergence failure
while {$analysisConverged == 0 && $tCurrent < $tGm} {
		
     # analyze one step,
     set analysisConverged [analyze 1 $timeStep]

     # if the analysis fails try reducing the time step
     if {$analysisCompleted != 0} {
						
          # set the reduced time step			
          set reducedTimeStep 0.0002				
                        
          # analyze 100 steps with the reduced time step
          set analysisConverged [analyze 100 $reducedTimeStep]
     }
		
     # get current the pseudo time
     set tCurrent [getTime]
}