Steel erector bolt preference. TC or Hex?
Steel erector bolt preference. TC or Hex?
(OP)
Hello all,
Has anybody seen a trend towards the preference of tension controlled bolts for steel erection recently? I'm involved in a pretty large steel project relative to the town that we are located in and recently got an RFI from the steel guys wanting to switch from snug-tight hex bolts to tension controlled bolts. Most of the jobs we design are pretty small (1-2 stories), so this is the first time I have come across this request. For those of you who work on larger steel projects, is this the new normal? Should we be considering specifying TC bolts going forward on larger buildings or is it really a contractor preference and we should continue to spec snug-tight and let the contractor ask the question?
Thanks,
Brandon
Has anybody seen a trend towards the preference of tension controlled bolts for steel erection recently? I'm involved in a pretty large steel project relative to the town that we are located in and recently got an RFI from the steel guys wanting to switch from snug-tight hex bolts to tension controlled bolts. Most of the jobs we design are pretty small (1-2 stories), so this is the first time I have come across this request. For those of you who work on larger steel projects, is this the new normal? Should we be considering specifying TC bolts going forward on larger buildings or is it really a contractor preference and we should continue to spec snug-tight and let the contractor ask the question?
Thanks,
Brandon






RE: Steel erector bolt preference. TC or Hex?
RE: Steel erector bolt preference. TC or Hex?
RE: Steel erector bolt preference. TC or Hex?
RE: Steel erector bolt preference. TC or Hex?
RE: Steel erector bolt preference. TC or Hex?
I've had a contractor ask for these TC bolts (with the snap off portion) for all the bolts on the job - yes, even for beam shear tabs. They didn't want any confusion as to which bolt, where, what procedure at which location, etc. Is it overkill? Yes. But, it saves them installation headaches.
buck1017, as far as cost, I don't think that is necessarily your concern. As long as the contractor doesn't charge the owner a extra cost for it, you should be able to approve it as acceptable.
RE: Steel erector bolt preference. TC or Hex?
Agreed that contractors will want to use them for all bolts on a job to save on confusion - but OP should have a better idea of what TC bolts are meant for. Worth noting AISC recommends against using pretension bolts all over the place to avoid "banging bolts" - up to the engineer to decide if this is a concern.
RE: Steel erector bolt preference. TC or Hex?
RE: Steel erector bolt preference. TC or Hex?
There is a serviceability issue of bolt banging. For this reason some Engineers of Record do not allow pretensioned bolts in snug-tight joints. I do not think AISC recommends against this, though. Rather they leave it to the EOR to determine if it is an issue on a particular project.
RE: Steel erector bolt preference. TC or Hex?
Dave
Thaidavid
RE: Steel erector bolt preference. TC or Hex?
In contrast, I can't tell you how many times I've gone into a building, such as mech rooms or above ceilings, and found hex bolts loose. I've even found a few bolts missing nuts.
Although I give the contractor the option to use TC's or DTI's, they always use TC's. The "squirty" washers are a pain to use.
RE: Steel erector bolt preference. TC or Hex?
Where does AISC recommend against pretensioned bolts to avoid bolt banging? One Modern Steel article from 1999 states:
“ . . . the snug-tight condition typically results in bolt tensions close enough to the prescribed pre-tension for slip-critical connections. As a result, slip under thermal conditions and service loads will be a random occurrence independent of the installation technique.”
https://www.aisc.org/globalassets/modern-steel/arc...
RE: Steel erector bolt preference. TC or Hex?