For TOTN? It's not about torque, it's about rotation. Witness the placement of the markings before rotation. If you didn't do that, you can't actually verify TOTN.
On bridges, regardless of what method is used to tighten bolts, atorque wrench is used to check bolt tension. There are many varibles that can effect tension vs. torque. Therefore although tables exist corralting torque to tnsion, the torque vs. tension is generally calibrated by means of a skidmore device. Although not crucial for bearing connections, the right bolt tension is crucial for friction connections.
I have been able, all beit for building contruction, to use TDI washers(google squirt washers). The washer squirt a goo ,for lack of better description, once a pre determined tension has been reached. They are a little procey but allow for visual inspection.
I am also a little confused because I have also always been told it has nothing to do with torque it has to do with rotation.
So let me see if I have this correct you bring all plies to a snug tight condition (all plies in contact). Next you determine the method of tightening TOTN or some type of pretensioning. TOTN is based on the amount you turn the nut to get a specified amount of pretension. I assume this amount is somewhat less than the amount of tension that is achieved in a slip critical connection (Table 4 9th edition). There is not a lot of information on the amount needed for tensioning in the TONT.
I was fine with all of this but when you review the thirteenth edition of the AISC it is now called the Turn of the nut pretensioning. Was the name changed just to sound more like the other methods of tightening or are they really trying to put more of an emphasis on the amount of tensioning going into the bolt?
