Shear Studs Per AASHTO?

[blueace]

Can anyone tell me if AASHTO has any provisions for welding shear studs through a metal pan for a composite beam? We understand that welding shear stud through the metal pan is common practice but can not find any provisions in AASHTO that address the practice. AISC allows the practice.

Thanks

 

[HgTX]

Since you're asking about AASHTO, I assume you are talking about bridges. Welding provisions for bridges are in AWS D1.5. Welding studs through decking is NOT common practice for bridges. This is considered a nonprequalified application and requires special testing.

Hg

Eng-Tips policies: faq731-376

 

[blueace]

HgTx thanks for the reply. Yes we are talking about bridges for we engineered a simple span composite beam girder bridge. You bring up a good point regarding the welding requirement per AWS. We are concerned that if the metal pan is continuous over the girder than the placement of the shear stud is offset from the centerline of the metal pan rib in order to avoid the dimpple in the metal pan. This places the shear stud closer to the web of the pan. AISC has specification to account for rib geometry base on rib height but we have not been able to find anything related to this with AASHTO.

 

[bridgebuster]

I didn't see anything in either the design or construction specs. AWS is vague. It doesn't mention pans however it says the base of the stud should not be galvanized.

I've worked on projects for several DOT's; none of them permit pans to be placed over girder flanges. There are angles that get attached to the edge of the flanges in order to create the haunch.

Also, some DOT's require preheating of the base metal, which can't be done if the pans are there.

 

[HgTX]

Have you looked at design guides put out by the pan manufacturers?

Also, every application of deck pan that I've seen of for bridges, it's just a stay-in-place form and has no structural application. Why does it matter where the stud falls with relation to the pan?

But why do you need the pan to be continuous across the beam? As bridgebuster points out, the DOT probably wouldn't let you do it. I wouldn't have, when I was with a DOT. Your DOT probably has standards for the use of permanent metal deck forms. Use those. (If your DOT doesn't, other DOTs do; TX is an example.) Simple-span composite beam bridges aren't rocket science and there's no need to get up to non-standard practices.

Hg

Eng-Tips policies: faq731-376

 

[blueace]

Thanks HgTX ...

No we have not yet looked at design guides.

The metal pan is perpendicular to the steel beam. One the shear stud is placed in each rib of the pan. The ribs have a ridge at the center of the rib which prevents the shear stud from being placed in the center of the rib. AISC notes a reduction of shear strength in the shear stud for rib heights greater than 1.5". Composite shear flow is perpendicular to the ribs.

We had detailed the pan as not being continuous across the beam but the contractor said that did not meet OSHA requirements and therefore wants to use continuous pans. I don't know if thats ture or not maybe the contractor justs wants to make it easier for him. The bridge is for a private party and not the CA DOT.