Fabricator substituting standard holes with short-slotted 1

[Wburger14]

Fabricator is asking for short-slotted holes where we spec'd standard holes. Steel member is a "typical" simple-span W-shaped beam with only gravity loads. Fabricator shows slots perpendicular to load (horizontal) as we'd like to see them. Connection is pretty standard stuff (from my vantage point) - designed as bearing with high strength bolts, threads included, finger-tight.

From a design/calc standpoint, are there any checks necessary to approve the short-slotted holes? My quick once-over of the code makes me think the fabricator's recommendation is OK. I'd like to approve the change as I know the short-slotted holes will help the erectors with fit-up.


Apologies as the Q may seem trite or simple but I'm an EIT with 2+ years of concrete design practice experience doing shops on my first steel design - just trying to save myself a bit of code-hunting.

2nd Q: Any other general shop drawing/CA/field inspection tips for a steel newbie?

 

[Ron]

Just make sure he uses plate washers instead of the standard washers. OK from there.

 

[apsix]

What's the reason for finger tight?
To me that implies you are expecting some horizontal movement within the joint, and therefore slotted holes would be expected.

 

[Wburger14]

Forgive me, snug-tightened bolts are what we truly spec'd and is reflected as such on the shops. Freudian slip above (I've been trying to self-educate on the AISC bolt spec and other steel lit quite a bit recently).

The short-slotted holes are necessary from the erector's perspective because we have a few bays of supported slab being expanded into a confined, existing space. Apparently all the long-slotted holes we included didn't keep them happy enough.

 

[connectegr]

Plate washers are not required for short slots.

What is the connection material? Single plate (shear tab) connections?

AISC 13th Ed allows for single plates with up to 3 1/2" eccentricity, with no consideration of eccentricity on the bolts (straight shear). SEE 13th ED p10-101

This applies to a single column of bolts only. For multiple columns eccentricity must be considered. And slip-critical bolts must be used with short slots.

This also assumes that the connection is not to a concrete embed. Single plates are "rigid" connection, therefore the embed must consider the moment, rather than shear only.

 

[Ron]

connectegr...agree plate washers not req'd. for short slots...many fabricators long slot the holes anyway when short slots intended.