Hydrodynamic Load On Column

[PEStructural]

Does anyone have any references or a way to design a column for hydrodynamic loads?

 

[AlohaBob]

ASCE has standards for designing structures in floodplain areas. They have design examples showing how to apply the effects. Or suggest ways to minimize loads.

 

[PEStructural]

Do you happen to know the reference?

 

[PEStructural]

Would it be applicable to an interior column in a circular steel tank? I'm designing an AWWA D100 steel tank center column which supports the roof. I can compute the impulsive and convective accelerations from D100 but I don't know how to apply them to the column.

 

[AlohaBob]

ASCE Standard SEI/ASCE 24-98 Flood Resistant Design and Construction.

 

[damstructural]

This is a tough problem to get an accurate answer because the hydrodynamic pressure will be very similar all around the column at any given instant (for an enclosed tank). The hydrodynamic pressure on the column will tend to cancel itself out (but not completely), like the hydrostatic pressure does (as a net force on the column). The magnitude of the hydrodynamic force should be much less than the interial load of the column itself and/or the lateral load from the tank roof. One valid approach is to neglect the hydrodynamic load on the column but add some safety margin to your design. Frankly, this problem is problably too complex to be worth trying to get an accurate answer, but there are ways to go about it.

You could adapt methods that were designed for concrete dams, which may add a lot of conservatism for a lateral load on a column. One way is to add mass to the column (for a dynamic FEA) based on Westergaard's equation or similar (Zanger or Chopra).

Or you could apply the hydrodynamic pressure distribution (from Westergaard or similar) as a psuedostatic force in addition to inertial forces.

I suggest checking out the online (free) USACOE engineering manuals for intake towers and hydraulic structures. Remember, an intake tower is a cantilever structure in an open reservoir - not the same animal. If you're still working on this, or if someone else is interested, I'll provide references to other papers that may help.