base size and soil requirements

 

The latest IBC 2006 code has really played havoc with our base sizes.  The elimination of zones and the addition of different earthquake values for each base has made it 
difficult to use turnkey plans like we used to.  Base sizes now vary so much that they can no longer be listed.  The soils pressures are also averaged and will probably be different when the engineering is completed on your tank.  These numbers can be used as a general reference when hiring a soils engineer to evaluate your site.  Please note that the dynamic (earthquake) loads on water reservoirs when compared to their static loading will be at a much higher ratio than would be expected in a normal non liquid containing building.  This is due to the 'slosh' affect of water moving within the tank during an earthquake. Have a soils engineer keep the numbers as high as the soils will allow.  

Tank Size: Static Pressure Dynamic Pressure   Tank Size: Static Pressure Dynamic Pressure
14 x 10 756 1358 20 x 10 762 1421
14 x 15 926 1938 20 x 15 952 1690
14 x 20 1218 3091 20 x 20 1248 2539
14 x 25 1509 4785 20 x 25 1544 3589
14 x 30 1622 5660 20 x 30 1960 5423
14 x 35 1609 5803 20 x 35 1966 5911
14 x 40 1599 5855 20 x 40 1970 6106
14 x 45 1506 5114 20 x 45 1873 5786
14 x 50 1509 5188 20 x 50 1884 5998
14 x 55     20 x 55    
14 x 60     20 x 60    
           
26 x 10 865 1352 30 x 10 775 1252
26 x 15 980 1626 30 x 15 988 1553
26 x 20 1280 2317 30 x 20 1286 2104
26 x 25 1579 3186 30 x 25 1583 2864
26 x 30 1857 4122 30 x 30 1963 4029
26 x 35 2031 4971 30 x 35 2274 5132
26 x 40 2075 5303 30 x 40 2226 5275
26 x 45 2112 5655 30 x 45 2383 5960
26 x 50 2142 5983 30 x 50 2330 5957
26 x 55     30 x 55    
26 x 60     30 x 60    

(Tank bases are listed as diameter x height)
(Pressures are listed as pounds per square foot)  

Tank Heights for the 14', 20' and 26' can go up to 75' tall.

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