Design a minimum-weight, hollow circular steel column for the water tank shown in Fig. 3.73. The weight of the tank \((W)\) is \(500 \mathrm{kN}\) and the height is \(20 \mathrm{~m}\). The stress induced in the column should not exceed the yield strength of the material, which is \(200 \mathrm{MPa}\), when subjected to a harmonic ground acceleration (due to an earthquake) of amplitude \(0.5 \mathrm{~g}\) and frequency \(15 \mathrm{~Hz}\). In addition, the natural frequency of the water tank should be greater than \(15 \mathrm{~Hz}\). Assume a damping ratio of 0.15 for the column.

Transcribed Image Text:

W D x(t) (t) FIGURE 3.73 Column of water tank subjected to ground acceleration.