Tank Ringwall Coring

[ConcreetnStele]

Looking for a source on the effects of twist moment on ringwalls.
I am analyzing/ checking tank ringwalls (100'+ dia.) for approval of coring for soil samples (2" holes). I am checking what would happen if the contractor cored through a bar. This area has considerable seismic activity, and the tank fluid level will be going up and down (assumed full for my calc). My loadings are coming from API 650 Appendix B and E, and the example I am following is the PIP-STE03020 Example 1. This is resulting in hoop tension using 90% of the capacity. The other 10% is being used by hoop twist.
The coring will happen in the top foot of the ringwall, total height is 3 ft. Since the twist moment adds tension mainly in the bottom bars and compression in the top bars, is there some way I can ignore or reduce the loading? All sources do not mention it, or use full hoop tension and twist, so I would be looking for something that may back up this idea.
Note that the load factors cannot be reduced, as far as I can tell.
Another question: why do we not use vertical seismic action for tension on the ringwall bars? Would this not add loading into the soil, hence into the bars?
Thanks

 

[StructEngBrah]

Why doesn’t the contractor use Ground Penetrating Radar (GPR) to avoid the reinforcing bars? That way you don’t have to worry about if they hit a bar.

A good coring sub will also be able to feel if they hit a bar and see metal shavings in the water. If they are paying attention they should not core through a full reinforcing bar, but they could knick it potentially.