rigid Link beam

[ryanp]

hi to all

in my model (steel 2d frame), I want beams behave as a rigid element, in other word i expect that beams don't have any deflections. in using 'rigidLink beam' command, I have a question and I am hopping that someone could help me.
please suppose one bay- one story frame (h is height of frame and L length of bay), which I want beam behaves as rigid element,
node 1 0. 0.
node 2 0. $h
node 3 $L 0.
node 4 $L $h
1. should I define any beam-column element for beam at first and then use 'rigidLink beam' command for node 3 and 4 or I should define rigidLInk command for these nodes, only? if I should define beam-column element, such as element elastic beam column, what values should I assign for A,Iz and E for defining it?

2. is it true?
fix 2 0. 1. 1.
rigidLink beam 2 4

sorry I have one another question
3.If I want to assign pin-connection at nodes 2 and 4, how can I define this?


Thanks in advance.
Thanks so much.

[MohsenShani]

1. rigidlink just need define base bay beam or truss action. its mean this element just "equal tow node" in 2D model. this element not have stiffnes or Real member.

2. if you assige pin connection, you need define this element for "slove" node.

[ryanp]

thanks for your replying.
for assigning pin-connection at node 2, is it true?

at first I add one node which has the same coordinate of node 2 ( this node as I mentioned above as constraint of 'fix 2 0. 1. 1.')
node 5 0 $h

then
equalDOF 5 2 1 2

I have a base question, is any internal force transmitted by rigid-beam to columns? because these internal forces are a function of section properties and as you mentioned, we don't define any element properties. thus can result making end pin-connection for a rigid element has no effect on behavior of structure. is it?
on the other hand as vsna has written in
http://opensees.berkeley.edu/community/ ... =2&t=29229
'' Rigid links are only MP_constraint objects. They are not elements.''

thanks so much again.

[MohsenShani]

correct, if your master node is "2", command : equalDOF 2 5 1 2 ,, if master node is "5" , command : equalDOF 5 2 1 2

no, internal force in rigid link is dosent exist. this element just made the "rigidDiaphragm" in 2D model.

Example:

(node 1)*-----------*(node 2) , *****command 1 : equalDOF 1 2 1 ;# made rigidDiafragm in 2D model***** OR *****command 2 : rigidLink beam 1 2*****
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Fix Fix

the 2 command like same action in your model., my suggestion you use command 2