Another bolt connection question?
Another bolt connection question?
(OP)
Hi, Guys, I have One more question on bolted connections, please see drawings in attached document. My question is:
1. In practice, there is always certain length of bolt that extrude out beyond the nut, is there any code requirement that specifies the minimum bolt extrude length?
2. If in a bolt connection, the bolt does not extrude out of the nut, but just flush with the nut (see lower drawing in attached document), will it reduce the bolt shear/tension capacity? If it does reduce the bolt shear/tension capacity, then how much it will reduce?
Thank you very much for your help.
1. In practice, there is always certain length of bolt that extrude out beyond the nut, is there any code requirement that specifies the minimum bolt extrude length?
2. If in a bolt connection, the bolt does not extrude out of the nut, but just flush with the nut (see lower drawing in attached document), will it reduce the bolt shear/tension capacity? If it does reduce the bolt shear/tension capacity, then how much it will reduce?
Thank you very much for your help.






RE: Another bolt connection question?
I think it is a question of good practice but not aware of any, if there are, technical explanations.
Maybe other forum members can help?
RE: Another bolt connection question?
I still recall the 1 or 2 threads sticking out. I worked in Europe for a while, so it is probably a requirement in some European code.
RE: Another bolt connection question?
Some contact documents and/or local codes may require you to have "stick-through" but this is not recommended.
I remember seeing in a Modern Steel Construction Q&A that there is a reduction for having the bolt not fully engaged in the nut but I couldn't find it. However, there is no reduction in the capacity of the bolt as long as the end of the bolt is flush with the nut.
EIT with BS in Civil/Structural engineering.
RE: Another bolt connection question?
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neffers
RE: Another bolt connection question?
Reason is the development of the strength of the male threads in the bolt (or stud), particularly when many bolts are threaded to the end, but the last part of the bolt is ground smooth so the thread is slightly tapered at the end. You need a little bit extending past the face of the nut to get the first engagement of the bolt threads into the (female) nut threads - which are often also recessed (or ground in the nut head) slightly.
I just checked several 1/2" and 5/8" coarse threaded bolts I've got available: It takes about 5/8 to 3/4 of one revolution just to get a male thread deep enough to begin pretending that it can develope full strength. A 1/2 square nut only needed 4-1/2 revolutions to get the bolt "flush" with the end of the nut, therefore the nut threads and bolt threads were actually only engaging for three revolutions. Same thing with the larger diameter 5/8" dia bolts: 4-1/2 to 5 revolutions are all are engaged, and since it takes 1 revolution to get a thread to full strength, by allowing "flush" bolts, you have cut your strength by 23%.
I know why the contractor/builder wants to allow "flush" nut engagements rather than "1-1/2 threads showing": - he doesn't want to check and replace lots of "too short" and "almost long enough" bolts.
I've been taught 1-1/2 threads minimum for that reason. But have not seen it in the Codes.
RE: Another bolt connection question?
BA
RE: Another bolt connection question?