MECHANICAL ANALOGIES FOR LIQUID STORAGE TANKS AND ACTION OF ECCENTRICGRAVITY LOADS

Mechanical analogies are widely used to represent the action of hydrod ynamic pressures induced by motion of the tank due to earthquake or ot her excitation. The liquid in the tank is typically replaced by two ma sses, one rigidly attached to the container, which represents impulsiv e pressures, and one connected to the container via a spring, which re presents the first sloshing mode. For taller tanks the action of eccen tric gravity loads, or the so-called P - Delta effects, should be cons idered, but questions arise as to what is the proper way of including these effects in the context of the mechanical analogies. This paper a ddresses these questions carefully. A general approach to obtain the p roperties of the equivalent mechanical model for a container of any sh ape is also described.