Applying partial fixity support

[Prafullamalla]

How it is possible to apply partial fixity support. I want to give 1/3 weightage to the simply supported beam and 2/3 weightage to the fixed beam. I want especially the result of plastic phase because of this I can not use superposition method.

[emjac]

Your question is a little unclear, but if I wanted to have a beam, with rotational springs at it's ends instead of pins, I might do something like this.

# Create ModelBuilder (with two-dimensions and 3 DOF/node)
model basic -ndm 2 -ndf 3

# Set parameters for overall model geometry
set length 360

# Create nodes
# tag X Y
node 1 0.0 0.0
node 2 0.0 0.0
node 3 [expr 0.1*$length] 0.0
node 4 [expr 0.2*$length] 0.0
node 5 [expr 0.3*$length] 0.0
node 6 [expr 0.4*$length] 0.0
node 7 [expr 0.5*$length] 0.0
node 8 [expr 0.6*$length] 0.0
node 9 [expr 0.7*$length] 0.0
node 10 [expr 0.8*$length] 0.0
node 11 [expr 0.9*$length] 0.0
node 12 $length 0.0
node 13 $length 0.0

fix 1 1 1 1
fix 2 1 1 0
fix 12 1 1 0
fix 13 1 1 1

set transfTag 1
geomTransf Linear $transfTag

set E 200000
set A 100
set Iz 10000

# this is the rotational spring stiffness
uniaxialMaterial Elastic 1 [expr $E*100]

# THis is the rotational spring
element twoNodeLink 1 1 2 -mat 1 -dir 3;

element elasticBeamColumn 2 2 3 $A $E $Iz $transfTag
element elasticBeamColumn 3 3 4 $A $E $Iz $transfTag
element elasticBeamColumn 4 4 5 $A $E $Iz $transfTag
element elasticBeamColumn 5 5 6 $A $E $Iz $transfTag
element elasticBeamColumn 6 6 7 $A $E $Iz $transfTag
element elasticBeamColumn 7 7 8 $A $E $Iz $transfTag
element elasticBeamColumn 8 8 9 $A $E $Iz $transfTag
element elasticBeamColumn 9 9 10 $A $E $Iz $transfTag
element elasticBeamColumn 10 10 11 $A $E $Iz $transfTag
element elasticBeamColumn 11 11 12 $A $E $Iz $transfTag

element twoNodeLink 12 12 13 -mat 1 -dir 3;

set P 100

pattern Plain 1 "Linear" {

# Create nodal load at node 4
# nd FX FY MZ
load 7 0.0 [expr -$P] 0.0

}

# Create the system of equation, a sparse solver with partial pivoting
system BandGeneral

# Create the constraint handler, the transformation method
constraints Transformation

# Create the DOF numberer, the reverse Cuthill-McKee algorithm
numberer RCM

# Create the convergence test, the norm of the residual with a tolerance of
# 1e-12 and a max number of iterations of 10
test NormDispIncr 1.0e-12 10 3

# Create the solution algorithm, a Newton-Raphson algorithm
algorithm Newton

# Create the integration scheme, the LoadControl scheme using steps of 0.1
integrator LoadControl 0.1

# Create the analysis object
analysis Static

recorder Node -file nodes.out -time -node 1 2 3 4 5 6 7 8 9 10 11 12 13 -dof 2 disp

analyze 10

remove recorders

[Prafullamalla]

My question was, the fixed beam with UDL load has end moment qL^2/12. Now I want to resist 70% of end moment,. Therefore, releasing 30% end moment.

[christopharjester]

How do I recover lost files with using partial fixity support of Opensees.exe

[emjac]

With the script I have posted you are about 90% of the way to solving your problem. You need to modify the script now to add uniformly distributed load instead of the one point load I inserted and play with the stiffness value of the rotational spring until you get the moment resistance you want.

[Prafullamalla]

Thanks