Column to Base Plate Welding 1

[JLNJ]

When CJP welding a column with a 2" thick flange to a 2" thick base plate (to achieve base fixity of the column) what are the pitfalls with regard to making the weld? Any concerns with delamination of the thick material or tearing of the weld in such an application? This is in an area of low seismicity.

 

[phamENG]

I don't typically deal with material that thick, but I have found a few articles about it on the rare occasions it's come up for me (though your particular question has not).

Welding Heavy Structural Steel (The Article)
Welding Heavy Structural Steel (The Paper)
Residual Stresses in Thick Steel Plates

 

[HTURKAK]

I am not sure if development of plastic hinge is required and will not remind AISC 341.
Lamellar tearing for this thickness is a major concern for the base plate.

I would suggest,

- If the base plate is compression controlled , 2" thick base plate is OK with PJP groove weld. Welding procedure should address also preheating , UT test requirements .
- If full development of plastic hinge is required at the bottom of the column, i would prefer base plate having less thickness with gusset plates or extend the column below the base and embed in concrete or encased in grade beam to get full fixity.

The following excerpt from ECCS Design of Steel Structures for Buildings in Seismic Areas..

My opinion only..






Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[JLNJ]

Thank you HTURKAK. This is in an area of low seismicity, so no interconnecting grade beams and no adherence to AISC 341. Your detail is quite robust; however, the expense of it would throw local contractors into anaphylactic shock.

I am interested in the lamellar tearing since all the stresses of base fixity are accumulated in the column base to base plate weld (in tension). My preference would be to have a bracket with welds in shear. This is obviously more expensive than a simple base plate attachment. I also have been ruminating on all the concrete Anchorage/Embedment/Development threads when it comes to anchoring a column to an isolated foundation with no pier. We embed the rods into the footing but the "around the corner" moment development doesn't happen like it can with rebar thru a corner joint.

 

[canwesteng]

You should require the base plate material to be inspected for lameral defects.