What type of cast-in-place anchor bolts are considered untorqued bolts? 2

[ofthesea]

In reference to ACI 318-11, section D8.1, spacing for cast-in-place un-torqued bolts, is 4d. If they are torqued cast-in-place bolts, or post installed, they are 6d.
My question is whether all cast in place snug-fit bolts, that have a nut/washer top connection, should be defined as torqued? Or are torqued bolts only those that have a required pre-stress load.
We’ve seen many metal building manufacturers sending out designs with 4d bolt spacing, but we've argued that only nelson stud type cast in place anchors are considered un-torqued?
Anybody have any insight to this?

 

[EngineeringEric]

May be wrong, But is it epoxy vs wedge anchors.

 

[ofthesea]

No, this question has to do with cast-in-place, torqued vrs untorqued, only.

 

[TehMightyEngineer]

I've never seen anything concrete* either way. Both seem reasonable assumptions.


*Hah, I deserve punishment for that one.

Maine EIT, Civil/Structural.

 

[ChipB]

Torqued: You are placing the bolts in tension such that they will never go above that tensile stress, and the baseplate always has pressure on the concrete. We do it a lot for vertical vessels and stacks. No stress reversal, therefore, no fatigue.

MightyEngineer: That was bad....
So.....
I worked at an orange juice plant for a little while.
I got canned.
Reason?
I couldn't concentrate

Punish away...

 

[TehMightyEngineer]

Chip: Off topic but I recall reading somewhere (RCSC bolt spec I believe) that pretension in anchor bolts tends not to work as the bolts will "relax" in the concrete and loose a lot of the pretension.


Hah, couldn't concentrate. That's punny.

Maine EIT, Civil/Structural.

 

[ofthesea]

Chip,
Are you saying then that a snug tight, cast in place anchor bolt is considered un-torqued similar to a nelson stud?
ACI appendix D refers to un-torqued cast in place anchors and I wondered if they could be both nelson studs as well as snug fit threaded L bolts.

 

[TehMightyEngineer]

Well, snug-tight to me means that there is some minimal pretension though the pretensioning torque is probably relatively low.

Maine EIT, Civil/Structural.

 

[paddingtongreen]

If they are only snugged, they are untorqued. Snugging is the necessary, you cannot leave the nuts clear of the baseplate. Snugging is something performed before torquing, not as part of it.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

 

[ofthesea]

Paddingtongreen,

I'm a believer of that too but do you have any reference to back that up?

 

[Ron]

Anchor bolts, whatever designation, are not "torqued". Snug tight is sufficient.