What tensile load to design column splice for?

[kk88818]

What tension load to design column splice for? I am designing column splices for my power station structure. Now, there is significant axial compressive loads on my columns, but not very large tensile loads (say, less that 35 kips). Is there a minimum tensile load that I should design my column splice for? 1/4 of the tensile capacity of the column? Half of the tensile capacity of my column? Please advise.

Also, OSHA 1926.756(d) states that, for column splices,"Each column shall be designed to resist a minimum eccentric gravity load of 300 pounds (132.6 kg) located 18 inches (.46m) from the extreme outer face of the column in each direction at the top of the column shaft." Does anyone know anything about this, and have you used it before?

 

[csd72]

the 300 pound load is for iron workers hanging off the columns.

 

[kk88818]

Thanks for the quick response, csd72. Hmm, never thought that the 300 pounds located 18 inches from the extreme outer face of the column in each direction at the top of the column shaft is for iron workers hanging off the columns, but it does make sense. Now, this 300 pound load at 1.5 foot away from the column would generate a moment of at least 300# * 1.5 Ft = 450 Ft-#, or more as the 1.5 Ft. is only to the face of the column.

Now, there would be a couple generated on the bolts horizontally, equal to 450 Ft-Pound divided by the spacing between the couple, is that right? Hope you can elaborate on this. Besides this, what is the minimum tensile load that the column splice should be designed for?

 

[jike]

I know of no requirement to design for tensile load other than what the structure would see under a loading condition that produces maximum uplift in the column. A normal column splice would be able to resist some tensile force.

 

[csd72]

k88818,

It would be more than that as your moment is around the center of the column and the 18" is from the face of the column. I would check in both axes.

 

[valleyboy]

Is there a requirement where you are working to design your structures for the requirement to avoid disproportionate collapse ?

If so, the splice should be designed to resist the ultimate vertical reactions from the floors beneath it (in tension).

I believe that this is to replicate a situation where the bottom length of column is removed during an accident - in this event the splice will need to resist the column axial load in tension.

Obviously, there would be significant distortion to the structure in this event, but it wouldn't immediately collapse.

VB