Stiffener & Doubler weld 1

[kaffy]

Good Morning Fellow Engineers,

I'm working on a project with multiple full-length transverse stiffeners & doublers welded along the beam. Original Plan was to weld continuously on all sides—across both flanges and the web. However, I'm concerned about potential warping due to the extensive welding required. To mitigate this, I am considering using intermittent welding for all doubler & transverse stiffeners (both bearing and intermediate stiffeners). I reviewed the AISC requirements but didn’t find much detail on intermittent welding for those. Are there any guidelines or references available for intermittent welding in these applications?

Thank You
Komaldeep Singh

 

[BridgeSmith]

For bridge girders, transverse stiffeners are only welded to the web, with fillet welds on both side that are stopped 1/4" short of the end of the stiffener. So a 24" tall stiffener would have a fillet weld 23 1/2" long on each side. Stiffeners for rolled shapes are held 2" clear of both flanges. Stiffeners for welded plate girders are clipped on the inside corners and fit to the flanges, but not welded to the flanges.

Connection plates for cross-frames or diaphragms are sometimes welded to the flanges, again with fillet welds that held 1/4" short of the edges.

 

[DrZoidberWoop]

I've rarely had to apply multi-pass welds for doubler plates (except in columns due to panel zone shear & similar). Unless you're dealing with very thin beams, the welds for the reinforcement likely won't cause warping. If a LOT of reinforcement (and welding) is required, the best path would be to upsize the beam. This is because it reduces the need for stiffening and therefore labor and welding time, which are the most expensive part of the fabrication process.

 

[kaffy]

Actually, I shouldn’t say "a lot of welding." I have a 45-foot-long W40x324 beam with four doublers (two at each corner, 1 on each side of web) and 26 stiffeners (13 on each side of the web).

 

[kaffy]

For bridge girders, transverse stiffeners are only welded to the web, with fillet welds on both side that are stopped 1/4" short of the end of the stiffener. So a 24" tall stiffener would have a fillet weld 23 1/2" long on each side. Stiffeners for rolled shapes are held 2" clear of both flanges. Stiffeners for welded plate girders are clipped on the inside corners and fit to the flanges, but not welded to the flanges.

Connection plates for cross-frames or diaphragms are sometimes welded to the flanges, again with fillet welds that held 1/4" short of the edges.

Thank you very much. Just the information I was looking for. Are those requirements in AISC?

 

[DrZoidberWoop]

kaffY: ".......in these applications"

What is the application? The correct answers are going to depend on that.

 

[BridgeSmith]

Are those requirements in AISC?

They're in AASHTO; don't know about AISC.

 

[BridgeSmith]

Actually, I shouldn’t say "a lot of welding." I have a 45-foot-long W40x324 beam with four doublers (two at each corner, 1 on each side of web) and 26 stiffeners (13 on each side of the web).

That seems like alot of welding to me. Have you considered using a plate girder? You could reduce the welding to the flange to web welds (which is typically an almost fully automated process), and just the connection plates for bracing, assuming you need them. It would also allow you to compensate for the permanent load deflection, if you want to.

 

[icebloom]

AISC has requirements like the spacing of the intermittent welds both longitudinally, transversely, etc in built up members.

 

[BridgeSmith]

If the beam is subjected to significant cyclic loading, be aware the fatigue stress limit for intermittent welds is considerably lower than for continuous welds.