Where (P_i) is impulsive force, (W_i) is impulsive liquid weight, and (S_DS) is the short-period spectral acceleration from the site geology. The convective force uses (S_D1) (1-second period) instead.
In the field of civil and structural engineering, the design of liquid-containing structures—such as water treatment plants, reservoirs, and wastewater facilities—presents a unique set of challenges. Unlike typical buildings, these structures must account not only for the inertial forces of the structure itself during an earthquake but also for the complex hydrodynamic forces exerted by the contained liquid. The American Concrete Institute’s , titled “Seismic Design of Liquid-Containing Concrete Structures and Commentary,” serves as the definitive standard for addressing these challenges in the United States. ACI-350.3-06.pdf
The in the file name indicates the year of publication: 2006 . As of 2024-2025, this standard has been superseded by newer versions (specifically ACI 350.3-20). However, the 2006 edition remains actively used for several reasons: Where (P_i) is impulsive force, (W_i) is impulsive