Bolted Angle as Transverse Stiffener on a Built-up Girder

[waytsh]

I am looking for references that address the use of bolted transverse web stiffeners as opposed to welded. We have a situation where we need to increase the web shear strength of a built-up girder and due to the material around it welding needs to be avoided. I would like to use a full depth angle with one leg bolted to the web of the girder. There are no concentrated loads and web local yielding and web local crippling are not a concern. Appreciate if anyone could point me in the right direction. Thanks!

 

[KootK]

So what is the governing failure mode of the web at the moment? Web shear buckling?

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.

 

[Ron]

No. You need to include the flange. If you can bolt to the flanges with fabricated tabs on the angle and develop the loads, no problem.

 

[waytsh]

KootK, web shear buckling is controlling.

Ron - Both flanges? Some of the commentary in AISC 360-05 Section G2.2 makes it sound like it only needs to be the compression flange and then only if it is a single stiffener.

 

[KootK]

If you're only dealing with web shear buckling, and there are no substantial concentrated loads, then I would think that you could use bolted stiffeners to address that without connection to the flanges.

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.

 

[waytsh]

I agree, particularly if I am using NS/FS stiffeners. As far a required stiffener section properties I assume that is all the same. What about determining the bolt quantity and spacing to connect the angles to the web? Any idea where I might find some information on that?

 

[KootK]

What about determining the bolt quantity and spacing to connect the angles to the web? Any idea where I might find some information on that?

I've no idea where to find info on this and I would say that it depends on how you intend to analyze it. If it were me, and it was a column type analysis, I'd forget about trying to make the angles behave compositely and just make them beefy enough that they would work as two, non-composite pieces. Then surely three bolts would do the trick. There's nothing meaningful to be gained here by economizing piece weights.

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.

 

[bridgebuster]

AASHTO has guidance for spacing bolts; when I get to work I'll post them.

 

[BridgeSmith]

I would say that a bolted angle on only one side of the web may or may not preclude buckling of the web. A pair of angles with fully tensioned bolts, with the outstanding legs aligned, would fully stiffen the web at that point.