FEA on frame connection

[Larryhd2]

I have been tasked with providing a finite element analysis of a bolted connection in a moment frame for a building.

The connection is comprised of a steel beam welded to the face of an 8"sq x 24" long steel tube. A 6"sq steel column is then fed through the 8" tube and there are (2) bolts attaching the tubes together. Since this isn't a "prequalified" joint by AISC, a detailed analysis of the connection is being asked for.

I have done a fair amount of FEA modeling on plate structures such as medical gloveboxes, but I'm scratching my head over how to approach the modeling of this connection. I have used RISA3D for my modeling needs in the past, but I'm not sure as to how to go about modeling in the bolts, nuts and washers with this software. Since the loading passes through these bolts and is distributed over the wall of the tubes, this is a farily imporatnt part of the modeling. This model needs to be fairly exact given the stress spikes that can occur in these joints.

In any case, if anyone has any suggestions to help me with my modeling approach I would appreciate it. If there is a software package out there that maybe has some of these elements built in I would also appreciate hearing about them. As it is now I have to build the beam and tubes out of small plate elements within RISA.

Thank you,
Larry

 

[rb1957]

i guess you could model all the relevent pieces ... bolts, nuts, washers(?), and include the fastener preload etc ... IMHO i think the most you'd model would be the fastner positions and use spring elements to join the two part together. i wouldn't model the holes and bolts in the holes, and the clamp-up from the head and the nut, etc ...

or model the connection as a node, get the forces and moments being transmitted from one part to the other, and do a hand calc for the loads on the bolts.



Quando Omni Flunkus Moritati

 

[trainguy]

Have you considered the cost of a physical test instead of FEA?

This seems like a tricky analysis given contact, friction, etc. Does this need to resist any cyclic loads?

tg