seismic design of water tank foundations

[blihpandgeorge]

i'm looking at a foundation for a round fire water tank (10m dia x 5m high) that sits on the high side of a 2m retaining wall (long story). typically, these tanks sit on a very nominal strip footing, however i dont think this is appropriate here and we are thus piling. my question is about the lateral shear / seismic loads to apply to the foundations

we have contacted a heap of the tank suppliers and got a consistent response of this is out typical base fixing detail and no one has asked us for seismic design before.

my questions are thus:
1) is there a requirement to design for seismic, it is not a building so outside the NCC
2) is there any other design guidance for calculating the seismic load of water sloshing around?

thanks

 

[ShawThing]

Not sure about question 1.
In respect to question 2 could you start with the mass of water multiplied by an appropriate coefficient based on AS1170.4 acting at the centroid of the tank.

 

[Agent666]

1. Yeah it's not a building, but the earthquake doesn't know this.
2. If you can't find anything Australian, try NZS3106 (the NZ Design Of Concrete Structures For The Storage Of Liquids code). You'll find all you need in there, you'll need to account for the convective and impulsive components of the liquid loads. Simply taking the static water load time a coefficient won't quite cover what's occuring in practice regarding the sloshing of the liquid.

https://engineervsheep.com

 

[ShawThing]

Further to Agent666's response just had a quick look and AS3735- Concrete structures for retaining liquids code commentary actually references NZS3106 in respect to earthquakes and the movement of liquids.