FIXED BASE CALCATION

[sedesigner06]

I know there are a ton of threads about fixed vs pinned base. I am using a pretty standard fixed base detail (see attached) but am struggling to follow the load path within the connection.

I assume its a sort of belt and suspenders type connection between the shear and bending action of the weld between the plate and beam & and tension/compression of the vertical plates. My moments are relatively low (1500 k-in) so I am not to concerned.

Would anyone no a good resource for an example calculation on this type of connection? I have looked at the AISC design guide but found no example with this type of connection.

Thanks in advance for any help.

 

[mike20793]

The 'standard' fixed base detail would not have the stiffened base plate. Those are typically used in highly loaded (axial or moment) columns to resist bending in the baseplate. There's also no welds called out anywhere. Typically, the moment gets resisted by the flanges so there is usually a full penetration weld on each flange. The shear is transferred to the baseplate by the weld of the web to the baseplate.

 

[KootK]

I assume its a sort of belt and suspenders type connection between the shear and bending action of the weld between the plate and beam & and tension/compression of the vertical plates.

No, when this detail is required, most everything is needed in earnest and there is relatively little redundancy of load path.

Would anyone no a good resource for an example calculation on this type of connection?

Design of Welded Structures by Omer Blodgett is a great place to start (clip below).

Some more current information here: Link

I agree with Mike that this is not the usual approach for small moments.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[sedesigner06]

Thanks for the input, I agree I looked at a "non built up" base plate connection and got a plate thickness of 1 1/2'' which is not bad and I believe is easier than the proposed solution.

The EOR gave me this detail and told me to use it if we were going with the fixed base approach. I believe it will do the job just want to me sure I am designing it correctly as I am relatively unfamiliar with the connection and trying to figure out the load path.

Mike, I plan on adding the welds once I finish the calculation and figure out what the welds should be.