Continuous W-Beam Over HSS Column_Moment Connection

[hemal1214]

Hi,

This is in reference to steel design guide 24, HSS connections. The moment connection chapter is 4. The guide demonstrates an example (example4.1) for continuous W-Beam supported over HSS Column. My questions are

1) The example 4.1 does not include lateral load for design. Can I use the same connection for Main Wind Force Resisting System (MWFRS) or is it strictly limited to gravity forces? I am designing single story moment frame building.

2) If I can use the connection shown on example 4.1 for my MWFRS, My tensile load in bolt is significantly large due to large moment and comparatively smaller axial load. Can I use 4 bolts or more on each side of column to reduce tensile load in bolt?

3) I am also having hard time to satisfy the beam prying action criteria as my tension in bolts is significant and my beam flange width is larger which increases the tmin. reqd. to eliminate prying action larger than tf. Can I use a 1/4" plate welded to beam bottom flange to increase the tf such that tf>tmin.?

I would appreciate any kind of suggestion. Please find the attached document for reference.

 

[ash060]

You could always weld the connection if prying becomes to much of an issue

 

[csd72]

That is definately a pinned connection that they show in the first details.

Personally I would design it similar to a typical haunch connection and have two full height stiffeners on line with the edges of the column (similar to the photo shown).

design of the bolts for prying should be not more difficult than a normal connection.

 

[rscassar]

The calculations would be the same whether you are trying to transfer moment from the W-beam to the HSS column from gravity load cases or lateral load cases such as wind.

For moment connections involving W-beams spanning continuously over a HSS column I have always provided full height stiffener plates to ensure the continuity of the HSS flanges, a nice and chunky baseplate (typically 3/4") and tensioned bolts.

 

[hemal1214]

Thank you for your reply.

@ash060: Thanks for your reply.

@csd7: The HSS connection guide identifies the connection as moment connection. Before I was also thinking it is a shear connection. However, the guide doesn't.

@kikflip: I perfectly understand your reply. Is there any procedure to design the stiffener? or just use the thickness of HSS column? Also, Can we use 4 bolts on each side to reduce the tension in each bolt?

Thanks

 

[a2mfk]

Unless you absolutely must have a continuous beam, it may simplify things to stop the beam at each side of the HSS and then you have a more traditional moment and shear connection... With the right size beams (flanges) and HSS column you can use bypass plates at the bottom flange to avoid the local stresses in the HSS faces and sides...

 

[sshields]

I was studying this example not too long ago, and can someone please clarify the sizing the weld to the cap plate section. Where does the Ta/g and Ta/db+2b criteria come from?

Does this some how account for the bending stress that would be in the weld from the tension force in the bolts times the length of cantilever of cap plate?



Scott