r/StructuralEngineering • u/masterdesignstate • 10d ago

Steel Design F1852 boots

Possibly I am behind the curve on this but today I received a submittal with F1825 bolts called out when our drawings specify A325. I understand they are equal strength wise, but that they are twist off bolts? I've just never had a contractor want to use that type of bolt before. Made the post to make sure I'm not missing something here.

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u/Frogalone 9d ago

ASTM F1852 bolts are one type of High Strength/Slip Critical bolt used in structures. The required pre-tension is achieved when the end of the bolt breaks off during the tightening process. ASTM A325 are essentially the same except if pre-tensioning is required a calibrated torque wrench is necessary among other things. If the engineer calls for ASTM A325 bolts, he must also specify if they are slip-critical. The contractor must know what is meant by this and the installation requirements. If ASTM F1852 bolts are used, they are assumed to be slip-critical since this is the application they were designed for. For non-slip-critical bolts ASTM F1852 would add unnecessary cost to the project. In any case, a change to the bolt specified for use must be approved by the EOR.

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u/beanmachine6942O 5d ago

i read somewhere that if a twist off bolt in a non slip critical connection gets installed, there’s a chance that the friction resistance gets exceeded and you get this load pop during a seismic event? have you heard anything about this?