Anchor Bolt Detail Question

[StructuralEd]

Having always used hooked anchor bolts, I am wondering if it is appropriate to use straight shank bolts for larger diameter bolts, 2" for example, considering that it may be difficult to bend the rods?

I haven't designed the embedded lengths considering the hook in the past but added them as an added safety consideration.

 

[parrot77]

what are they anchored into? Concrete? You might consider straight bolts with oversize washers, plates or angles fixed to the end cast into the concrete. This forms a large surface area resisting bolt pull- out

 

[StructuralEd]

The bolts are always in concrete.
Is the supplementary hardware necessary?

 

[parrot77]

I have always used them. Typically where 4 holding down bolts are used to connect a column to a base I join the bolts wit two strips of 70mm x 70mm steel angle. Each of the bolts is also wrapped in an oversized plastic sleeve to allow the bolts to be adjusted to exactly fit the baseplate holes. There may be other methods but that is my preferred one

 

[VTPE]

if you are in a seismic design category C or worse, the ACI makes it very difficult to use hooked anchors. The preferred method these days is to use straight anchors with heads or nuts. See the ACI 318 code for requirements for anchors in concrete.

 

[cap4000]

I also over the past 30 years have used long straight shank bolts with 4 inch long hooks. Due to potential concrete crushing at the curved-hooked portion of the bolt the preferred method now is as parrot77 indicates. Depending on my loads I still use the old fashion way. What are your loads??

 

[Lion06]

AISC also recommends NOT using a hooked anchor bolt to resist ANY tension.

 

[StructuralEd]

Uplift might run 4 to 5 kips.
Most of the loads are generally shear.

I'm not convinced that having a mass of embedded horizontal steel (Ls) is not detrimental to the continuity of the pier,
so I guess a headed or nutted rod might be preferred to me.

I balk a little on the threaded base though because I am thinking of cutting oil not cleaned from the rod interfering with the bond.

 

[Teguci]

Add the nut at the bottom and you get your shear cone pullout resistance from the concrete. There is a calc to check bearing on the top face of the nut. If all is well, don't worry about oil on the bolt.

 

[jike]

StructuralEd: I know what you mean.... one of my pet peeves is going to a jobsite and seeing a barrel full of anchor bolts with cutting oil on the shanks. I have a note that specifically requires them to completely clean the shanks of all cutting oil. If the fabricator doesn't do it then the GC has to do it. Additionally, I stamp the shop drawings with the same note.

 

[msquared48]

I have used a detail with the straight threaded rod with a steel plate welded to the end and a bolt on the end of the rod. I have sized the thickhess and size of the plate to develop the uplift in the rod. Works for me.

Mike McCann
MMC Engineering

 

[StructuralEd]

All good ideas. Thanks,

 

[JStephen]

On one or two occasions in the past, I've used hooked bolts over 2" in size, and I'm not aware that they had any problems fabricating them. (I assume they are bent hot.) But as indicated above, the motivation to not use them is due to design strength rather than fabrication.