While the general building code (ACI 318) covers standard buildings, ACI 350 specifically addresses . The "350.3" subset deals exclusively with the dynamic forces generated during an earthquake.
If you are maintaining old infrastructure, it is indispensable. If you are learning, the 2006 edition provides the foundational logic of hydrodynamic seismic design with less complexity than the newest iteration. ACI-350.3-06.pdf
Search for the document by its full name on the official ACI website . If you only need the 2006 edition for legacy work, purchase the official PDF there. If you are starting a new project, buy the 2020 edition—but study the 2006 edition first to understand the evolution of the code. While the general building code (ACI 318) covers