Modeling Semi-Ridgid Connections

[TimmyH76]

What is the best way to model a semi-rigid connection with an FE program. Most of the ones I've used don't have this as an option. We are looking at the sway in a frame that has been lateraly loaded. Any suggestions? Thanks.

 

[csd72]

Not all packages can do this, even if your is capable then you may need to enter it as a spring constant in yours.

 

[TimmyH76]

Is it possible to set the connections as rigid and modify the modulus of the end portion of the member. Say for a member that is 14' long, take 2' at the end of the beam and modify the E value so that this allows for a small rotation. This is like the way Visual Analysis does it.

 

[DaveAtkins]

The program I use allows for a rotational spring.

DaveAtkins

 

[Lion06]

I am not sure if our program allows for a rotational spring or not, but even if yours does you will need to test the connection to get the moment-rotation curve.
We do a lot of type II with wind connection buildings (now called FMC connections). I model it as rigid connections and multiply the drift by 1.5 to 2. I got this number from a paper I read on the subject. If you would like the reference, let me know and I will dig it up.