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RE: Bolt retightening[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Bolt retightening
- From: "dave lowen" <jatech(--nospam--at)kwic.com>
- Date: Tue, 27 Sep 2005 07:52:40 -0400
The RCSC spec. on A325 bolts should provide all the information you need. You may download it from the AISC website.
V 519 587 5797
F 519 587 5138
V 519 749 9468
From: Kevin Below
I am in need of some guidance on the right technique for retightening bolts on a 40-year-old steel structure.
One of my clients, suspecting that the bolts in one of their many buildings were loose, asked me to check. Surprisingly, we found that his suspicions were founded.
The roof structure of this warehouse type building is the Gerber type (cantilevered beams alternating with suspended spans), and the beams that pass over the columns
have 4 bolts in the connection. These bolts are almost all loose. You can unscrew them by hand.
The original drawings call out hi-tensile bolts in non-slip connections, which is obviously not what they got.
There is no bracing in the building, and no concentric masonry walls, so I presume the lateral resistance comes from the non-slip joints of the beams over the columns, forming rigid connections. In this case, the beam-column connections should rightly be non-slip, and not bearing type.
So now I have to prepare plans and specs for tenders for the job of tightening the bolts.
My search of the steel manuals and text books and web sites
leads me to conclude that it is not simply a case of applying a torque wrench
to these bolts. In the old Canadian steel code (oh yeah, this job is
My first question is whether I should require new bolts, since I have no control or knowledge of the existing bolts. It seems like a good idea, especially if I need to calibrate the torque wrench.
Also, the idea of a machine to calibrate the torque wrench each day seems overkill to me, when this building doesn't seem to have suffered in its loose state for so long, surviving mild earthquakes and strong winds with no sign of distress, despite its lack of tightened bracing. Would the turn of the nut be sufficient, or is this really only for bearing type connections ?
What do the steel gurus think ?
Kevin Below, ing., Ph.D.
- Bolt retightening
- From: Kevin Below
- Bolt retightening
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