Which ASTM's designation must be used for a through-bolt for joining two HSS tubes?

[X4vier]

Specifically to join an HSS baluster to an HSS stringer in a metal stair?

 

[phamENG]

If you're talking about ASTM designation for the bolt, well that depends on the required capacity.

Keep something in mind though - through bolts in HSS aren't really "bolted connections" per AISC. They are pin connections and have to be designed differently.

That said...baluster to stringer probably isn't a high demand connection.

 

[BAretired]

I suspect the tensile capacity of the bolt is going to be determined by the wall thickness of the two HSS members.

BA

 

[dik]

From my notes:
-HSS THROUGH BOLT FASTENERS TO CONFORM TO ASTM A307, GRADE B. THROUGH BOLTS FOR HSS TO BE FINGER TIGHT. TORQUE TO 2.3N-M (20IN-LBS) (DO NOT CRUSH HSS WALL) AND THREADS SECURED BY PEENING, ‘JAM NUTS’, OR LOCTITE 263 (RED) THREAD LOCKER.

best to weld or to use plate expanding bolts.


Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[X4vier]

So, that bolt can be designed A307 Gr B?. Thanks

 

[dauwerda]

To expand on what phamENG stated in regard to pin connections, the Steel Tube Institute has a good article discussing through bolting of HSS that can be found here:

Connecting Hollow Structural Section Members with Through-Bolts | Steel Tube Institute

In this article, Jason McCormick, Associate Professor, Civil & Environmental Engineering, University of Michigan, discusses how to connect HSS section members with through-bolts.

steeltubeinstitute.org

When structural bolts are needed that fall outside of F3125 (A325) due to length, the AISC SCM (page 7-13 of the 15th ed.) states that "ASTM A449 bolts may be required for longer lengths".

My past experience with some bolt suppliers has been that A449 can be pretty difficult to source, the alternative that they usually suggest (and I have used) is ASTM A354 (grade BC would be close to A325 and grade BD would be close to A490).

Portland Bolt has the following information on their site regarding structural bolts:

Heavy hex structural bolts are designed for steel-to-steel structural connections. Consequently, they are typically very short. The A325 and A490 specifications are not intended for general applications, including anchor bolts. In these applications, substitutions of A449 for A325 and A354 grade BD for A490 should be considered.

 

[phamENG]

X4vier - we don't know. We don't know what the loads are on your connection or what size bolts you're using. A307 is probably appropriate, but you have design the connection and find out if it works.

 

[JLNJ]

Maybe Hollo Bolts are the way to go. It all depends on the geometry.

Regardless, the tube sidewall is probably your limiting constraint, not so much the bolt spec.

 

[jittles]

Typically go with basically what Dik stated - A307 mild bolts, finger tightened to avoid crushing tube walls. Using A307 lets you get longer lengths and they won't pre-tension the bolts like A325/A490 may be.

 

[dik]

that's why, for longer bolts, I use A307 because they are generally more common. Crushing thin tube walls is easy with almost any fastener. I guess they could act like a lock washer...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[BAretired]

A through bolt is the wrong type of fastener to use to connect a HSS baluster to a HSS stringer, regardless of its specification.

BA

 

[X4vier]

What can be a better connection for a baluster?

 

[BAretired]

What can be a better connection for a baluster?

Fillet weld all around, top and bottom.

BA