3d frames

[alessandro.paparo]

hi all!

i started an analysis for a 3d frames, now i'm emprooving studing a simple elastic 3d portal ( 4 nodes as constrain, 4 nodes free and 1 node for the rigidDiaphragm). also the masses are concentrated ad the 4 free nodes.
now i have 2 questions:

1) for the rotational inertia i have to put something or when i put the mass (for inertia of traslation) the programm calcultes itself the rotational inertia.
set m 30
mass 5 $m $m 1.e-9 1.e-9 1.e-9 1.e-9

IT'S OK OR I HAVE TO PUT A ROTATIONAL INERZIA AT THE DOF NUMBER 6?

2) i have some problem with the transformation from the local cordinates to the global cordinates: i don't understand how i have to put the vector vecxz... now i do as below:

a) - defined the nodes as follow:
set h 3000
set b 5000
node 1 0 0 0
node 2 $b 0 0
node 3 $b $b 0
node 4 0 $b 0
node 5 0 0 $h
node 6 $b 0 $h
node 7 $b $b $h
node 8 0 $b $h
node 9 2500 2500 $h (node for the rigidDiaphragm)

b) - i separated the elements (elastic beamcolumn) using the the x-axis for each local sistem. so it becomes as follow:
column ----> 1 0 0
beam in x direction (elements 56 and 78 ) ---> 0 1 0
beam in y direction (elements 58 and 67) ---> 0 0 1.

BUT I DON'T KNOW IF IT'S CORRECT


for more detail i put the script below:

model BasicBuilder -ndm 3 -ndf 6
set h 3000
set b 5000

node 1 0 0 0
node 2 $b 0 0
node 3 $b $b 0
node 4 0 $b 0
node 5 0 0 $h
node 6 $b 0 $h
node 7 $b $b $h
node 8 0 $b $h
node 9 2500 2500 $h

set m 30
mass 5 $m $m 1.e-9 1.e-9 1.e-9 1.e-9
mass 6 $m $m 1.e-9 1.e-9 1.e-9 1.e-9
mass 7 $m $m 1.e-9 1.e-9 1.e-9 1.e-9
mass 8 $m $m 1.e-9 1.e-9 1.e-9 1.e-9

fix 1 1 1 1 1 1 1
fix 2 1 1 1 1 1 1
fix 3 1 1 1 1 1 1
fix 4 1 1 1 1 1 1
rigidDiaphragm 3 9 5 6 7 8
fix 9 0 0 1 1 1 0

set BCol 400
set HCol 400
set BBeam 400
set HBeam 400

set A 160000
set E 30000
set G 10000
set J 1.e10;
set IyCol [expr 1./12*$BCol*pow($HCol,3)]
set IzCol [expr 1./12*$HCol*pow($BCol,3)]
set IyBeam [expr 1./12*$BBeam*pow($HBeam,3)]
set IzBeam [expr 1./12*$HBeam*pow($BBeam,3)]

set transfTag Linear
set ColTransfTag 1;
geomTransf Linear $ColTransfTag 1 0 0;
set BeamTransfTagX 2
geomTransf Linear $BeamTransfTagX 0 1 0;
set BeamTransfTagY 3
geomTransf Linear $BeamTransfTagY 0 0 1;

element elasticBeamColumn 15 1 5 $A $E $G $J $IyCol $IzCol $ColTransfTag
element elasticBeamColumn 26 2 6 $A $E $G $J $IyCol $IzCol $ColTransfTag
element elasticBeamColumn 37 3 7 $A $E $G $J $IyCol $IzCol $ColTransfTag
element elasticBeamColumn 48 4 8 $A $E $G $J $IyCol $IzCol $ColTransfTag
element elasticBeamColumn 56 5 6 $A $E $G $J $IyBeam $IzBeam $BeamTransfTagX
element elasticBeamColumn 87 8 7 $A $E $G $J $IyBeam $IzBeam $BeamTransfTagX
element elasticBeamColumn 58 5 8 $A $E $G $J $IyBeam $IzBeam $BeamTransfTagY
element elasticBeamColumn 67 6 7 $A $E $G $J $IyBeam $IzBeam $BeamTransfTagY




THANK YOU!

[silvia]

you have to assign the torsional inertia. i think if you assign masses at the element nodes you might get a better approximation, otherwise.

for the transformation, look at the images in the manual, and work it out with someone in person. it takes a bit of time to figure it out the first time.

[alessandro.paparo]

ok

thx!