Ground Movement & Foundation Bolts

[CuriousElectron]

Greetings,
I have a question regarding sole plate and foundation bolts. In a scenario where a metal sole plate is anchored to concrete with anchor bolts, and over time, if a ground movement occurs, would the torque value on the anchor bolt change relative to the original torque value? The anchor bolt is installed vertically.
Would this horizonal ground shift, even if it is less than a millimeter, would if cause the loosening of the bolt?
Thanks,
EE

 

[r13]

No. From my experience, bolt loose is usually caused by vibratory loadings from repeat shaking and stress reversal. The movement described by you (in plane torque/twist) will push the bolts and sole plate into bearing. After that, the bolts could be deformed, or sheared off under significant movement that pushed them beyond the design strength.

 

[desertfox]

Hi CuriousElectron
If there was horizontal thrust which leads to movement between the sole plate and the concrete then eventually the nut could be loosened by that action, the torque value doesn’t really matter but was does matter is the bolt tension and torque is only one of several means of generating bolt tension. The bolt tension over time can change due to many different things like, temperature, creep, bolt relaxation. If you can explain in more depth your problem we may be of further help.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein