ICC 500 Hydrostatic Load

[AB25]

Hello All,

I would appreciate any guidance with the ICC 500 (Hydrostatic Load) requirements. Section 303.4 of the ICC 500 states that "Underground portions of storm shelters shall be designed for buoyancy forces and hydrostatic loads assuming that the ground water level is at the surface of the ground at the entrance to the storm shelter" It also gives an exception to design for a lower ground water level if adequate drainage is available.

I'm designing an underground community tornado storm shelter that is 10' below grade. How can I, the Structural Engineer, justify the lower water table? Would assuming the basement wall backed with granular material and a perforated pipe that collects and drains the water (which is typically done in basement walls) is sufficient to justify the lower ground water level? If not, what needs to be done to justify it?

I would appreciate your suggestion.

 

[KootK]

Granular material and perforated material sounds like a good start. However, I would think that you'd also need a mechanism for getting rid of that collected water somehow. With the basement walls of a conventional building, that mechanism is often a sump pit with a pump designed to handle the requisite flow. You may need something like that in your storm shelter which might be a pretty tall order considering that:

a) The flow that might be involved is likely significant.

b) Most sumps rely on electricity which may be in questionable supply during a serious storm. I suppose that the sump could be run from a generator if one could rely on a competent generator operator to be on hand.

 

[JLNJ]

It sounds like the code is strongly encouraging you to NOT put such a shelter below grade. Maybe the Owner needs to reconsider.

 

[XR250]

Can the pipe drain to daylight (an area that cannot flood )? If not, I would design for the full 10 ft.