Column Splice

[BAGW]

Hi,

I have a question regarding column splice design. I have a W14x311 column which needs to be spliced. The gap between the upper column and lower column is zero. The upper column is bearing on lower column. Compression forces are 3000kips and 2000kips. At the splice location as upper column is bearing on lower column, I tending not the design the splice for 3000kips compression force. I am designing the column splice only for 2000k tension force. Does this make sense? Is this addressed anywhere in AISC code? Thanks

 

[MotorCity]

Design for the tension splice forces. Are those ASD or LRFD forces? Don't forget about designing for any column shear forces also.

 

[Nor Cal SE]

Like MotorCity has said, design the splice for the load(s) seen at the exact location of the splice. If this is 2000 kips, then you have no need to design for a greater axial load even if the lower column sees 3000 kips total due to tributary load and framing members that add load to the lower column below the splice location.

Also as MotorCity has noted, be sure to design the splice for loads other than axial, such as shear and moment. But if your columns are entirely gravity resistance and not part of lateral-force resisting system, then I would imagine you have no shear or moment.

 

[JLNJ]

AISC has a whole section on splices. Design the joint for the forces in it.

Or just ask random people on the internet, it's only 2 or 3 million pounds.

 

[KootK]

You're asking whether or not you have to design for the compression load, right? If so:

1) No, not for columns. You do, at least in part, though for other things like truss compression chords etc.

2) For columns, the requirements are:

- the connection parts have to keep the splice together (vague).
- if shims are not used, the gap has to be 1/16" or less.
- if shims are are used, the gap has to be 1/4" or less and the shims may not be tapered.

You probably want to get your hands on an AISC Code of Standard Practice. A lot of this kind of thing lives there.

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.