Aci-350.3-06.pdf Jun 2026

The most critical concept introduced by ACI 350.3-06 is the breakdown of the liquid mass into two distinct components during a seismic event. The standard utilizes the mechanical analogy originally developed by Housner and refined over decades:

ACI 350.3-06 covers a wide range of tank geometries and construction types, including:

The total base shear is calculated by combining these two components using the SRSS (Square Root of Sum of Squares) method:

ACI 350.3-06 establishes the industry standard for the seismic design of liquid-containing concrete structures, defining procedures for calculating impulsive and convective (sloshing) hydrodynamic forces. The standard provides technical guidelines for designing both circular and rectangular concrete tanks to ensure stability during seismic events. For a preview of the document, see this Scribd publication ACI-350.3-06.pdf

Unlike buildings (Risk Categories), ACI 350.3 defines three Seismic Use Groups:

By calculating these two components separately, the engineer can apply appropriate response modification factors (R‑factors) and obtain a more accurate representation of the actual dynamic behavior.

While this article focuses on the -06 edition, it would be incomplete without mentioning that ACI released in 2020. The newer edition aligns with ASCE 7-16 and introduces important changes: The most critical concept introduced by ACI 350

The code applies to rectangular and circular concrete tanks, reservoirs, and basins. It explicitly covers structures containing liquids with mass density up to 75 lb/ft³ (similar to water). Importantly, it excludes pressure vessels and buried tanks where soil provides restraint.

Some of the key provisions of ACI 350.3-06 include:

As of October 2021, ACI 350.3-06 has been by a newer version: ACI 350.3-20 , "Code Requirements for Seismic Analysis and Design of Liquid-Containing Concrete Structures (ACI 350.3-20) and Commentary." However, the 2006 edition remains relevant for existing infrastructure, legacy designs, and situations where project specifications or local regulations still reference the older standard. For a preview of the document, see this

: Provisions for the structural design of concrete tanks and similar structures, including considerations for strength, serviceability, and durability.

To effectively implement ACI 350.3-06, engineers should follow best practices, including:

ACI 350.3-06 is a supplement to ACI 350-06, "Code Requirements for Reinforced Concrete Structures" and provides specific requirements for the seismic design and detailing of reinforced concrete structures. The standard is intended for use in regions of high seismicity, where structures are subject to significant earthquake forces.