Steel to Concrete Stair Connection

[infinitehg]

I'm working on a project which I have guidelines for, but I'm stuck as far as specs go.

The client needs new staircases. Existing staircase will be demolitioned but the existing concrete landing will remain.

The only guidelines that I have is that bolts must be ASTM A325 or A490 bolts, but must be a lag bolt. I need help in finding out what specs I need for the size of the bolt that is graded for outdoor use, and falls under the ASTM.

Any help please.

 

[dhengr]

Infinitehg:
ASTM A325 or A490 bolts, and lag bolts just don’t make sense. A325 or A490 are stds. for structural bolts and nuts, not a spec./std. for lag bolts. And, lag bolts into concrete doesn’t make much sense either, unless the lag bolts go into expansion shields. It sounds like the guidelines or specs. for this job, or your interpretation of them, are all mixed up. I think you should design the new stairways and their connections to meet the local bldg. code, and the use std. and readily available hardware to do this. You might consider expansion bolts or epoxied bolts once you know where you can put them in the landing slab, without cutting existing rebars.

 

[Ron]

You won't find any! As dhengr notes, you have an incompatible and improper specification reference.

Lag bolts are not used to attach to concrete...they are used to attach to wood/timber. They will need to be sized based on your loading requirements for the stairs.

If your bottom landing is concrete, expansion anchors or chemical anchors are typically used as dhengr notes. For the top connection of the stringers to supports, you will either need expansion/chemical anchors if into concrete or lag bolts/through-bolts if wood.

 

[Duwe6]

There are fasteners for concrete that consist of a lag screw into a lead sleeve. They get used for non-calculated joints only. As per the above advice, use expansion 'Hilti' bolts or chemical 'epoxy' anchors. If you actually need something with high shear strength, similar to A325 & A490, use
custom-length A192 B7 threaded rods, epoxied using a name-brand, load rated 'chemical'. Epcon & Hilti come to mind.

The better fastener suppliers cut their own B7 studs, starting from a 20-ft length stock, so getting 1, 1.5, & 2-ft lengths is easy.

 

[zcp]

Welcome to 'the specs may not be right' 101. Design the way it needs to be done and have them mark it up, or send an RFI to clear up. Your schedule may determine which you have time for.....

ZCP

http://www.phoenix-engineer.com