SEISMIC LOAD ON POST IN TANK

[CUTiger1989]

I need some code advise.

We have been asked to perform anchor bolt certification for seismic loading on a tripod supporting a hanging floater in an in-ground wastewater treatment tank. Each leg of the tripod is anchored to the concrete base with (4) - 1/2" diameter bolts. The hanging floater weight is minimal.

My question ... we know that, in the event of seismic activity, the wastewater will slosh within the tank. It may be full; it may be half-full. However, due to limited time, I have not been able to research the code-prescribed loads on the tripod posts. I liken it to an oil rig. That may be a bad comparison, but there will be a pressure on the tripod legs due to sloshing of the wastewater similar to the wave action on the oil rig supports. Does anyone have any advise when to locate this type of loading in the code (IBC 2009 and/or ASCE 7) or in a technical reference?

Thanks!

 

[JStephen]

Bob Wozniak wrote a paper giving the basis of seismic design in API-650, I think in 1978 or so. The appendix to that paper includes a derivation of the force on tank columns (ie, vertical cylindrical shapes in the sloshing fluid) that might be helpful.

It might be simpler to derive the maximum strength of your structure, and base anchorage requirements on that.

 

[CUTiger1989]

Thanks for your reply. I have found that API standard and looking through it.