Assumption of steel connection being rigid or pin
Assumption of steel connection being rigid or pin
(OP)
When assuming the fixity of a steel connection, how should I assume whether it is fixed or pinned? For example, a rectangular hollow section welded all round to another hollow section. Is there a way to classify/justify whether a connection can be considered as rigid or fixed??
Thanks for reply.
Thanks for reply.






RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
With all that said, I don't think there is a cut and dry one size fits all answer. I'd consider looking at it both ways and get a comfort level with what's going on. For example, let's say you model it fixed and your analysis shows it transfers 10 k-ft of moment but the connection has a capacity of 100 k-ft. I'd think that could be considered fixed because you have so much reserve capacity that clearly it's going to be stiff.
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
ynnuseel0106:
1. If your beam is designed to be simply supported and the end connections are welded all-around, then those connections will need to appreciably deform/fail in order to re-distribute moments to the midspan.
2. Transversely loaded welds are extremely stiff and brittle, so in order for number 1 to occur it would take a great amount of end rotation. Until that fuse forms, moment will be transferred into the column.
So, yes it will be a problem if your column (and base plate, etc.) isn't designed to resist the moments that develop from the rigid beam end rotation.
You should review the Fully and Partially Restrained Moment Connection configurations in the AISC Steel Construction Manual. There you can get a better feel for those connections configurations that are rigid, partially restrained(traditionally called "wind moment connections"), and by process of elimination non-rigid or simple.
"It is imperative Cunth doesn't get his hands on those codes."
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin
"It is imperative Cunth doesn't get his hands on those codes."
RE: Assumption of steel connection being rigid or pin
RE: Assumption of steel connection being rigid or pin