Why is preload not considered in the verification of anchor bolts?
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As the title suggests, if the pre-tension is high, during operation the axial pull force on the bolts caused by the seismic load moments combines with the bolt pre-tension; does this mean the bolts are overloaded? So why isn’t this taken into account during verification? I’ve never been able to figure it out; something similar applies to the bolts of flanges as well……
The forces acting on anchor bolts are different from those on flange bolts; there is no such concept as preload. There are also specific requirements regarding the way in which anchor bolts should be tightened during installation, and a safety factor is taken into account as well. Therefore, it’s not a problem even if the anchor bolts are tightened a bit too much.
The function of flange fasteners is primarily to prevent leaks, while anchor bolts serve solely for structural connection.
There is no sealing issue with the anchor bolt connection, so pre-tensioning does not need to be considered.
Thank you all for your replies. Could you please explain the superposition of the axial force generated by the sealing preload and the operating pressure?
The bolt stretches under tension and can continue to elongate, so I feel that the tensile force on the bolt is still increasing