Design of earthquake-resistant liquid storage tanks

For an approximate evaluation of design seismic loads acting on vertical cylindrical tanks with liquid a simplified dynamic model is adopted.According to the model, an “impulsive” part of liquid is regarded as associated with a tank body and performing horizontal vibrations simultaneously with it during an earthquake. A “convective” part of liquid involved in the slosh wave formation process on a free surface performs independent vibrations having frequencies which are significantly lower as compared to natural frequencies of the tank body and dominant frequencies of an earthquake. The design model takes in consideration soil stiffness of the tank foundation under elastic uniform shear. Determinations of moments due to seismic loading, lateral forces, normal pressures on the tank shell, contour pressure on the tank bottom and also of the height of surface wave for two levels of seismic actions are provided. When friction forces are exceeded at the tank foundation, seismic displacements in sliding which are limited by the deformability of inlet pipelines can be determined.