The original ACI 350.3-06 is now designated as by the American Concrete Institute, although a PDF version may still be available for purchase. On the official ACI website, the product page for this standard notes that “a newer version of this document exists” and directs users to the current edition, ACI 350.3-20. Nevertheless, the 2006 edition remains in widespread use, especially for projects that reference older building codes or for legacy system evaluations.
The total base shear is calculated by combining these two components using the SRSS (Square Root of Sum of Squares) method:
Before the introduction of ACI 350.3, the seismic design provisions for liquid-containing concrete structures were, by many accounts, "very limited in scope". The 1989 edition of ACI 350 offered only a general description of fundamental principles, leaving engineers to rely on a handful of industry standards that primarily focused on a single type of structure. Notably, the AWWA D110 and D115 standards existed for , but they did not cover the broader range of structures encountered in practice. Furthermore, general building codes like the IBC, UBC, and ASCE-7 either largely refrained from covering these structures or only provided simplified equations for calculating base shear forces, which proved insufficient for detailed design. ACI-350.3-06.pdf
One of the most practical sections in ACI-350.3-06.pdf is Chapter 6: Freeboard . It calculates the maximum vertical height of sloshing waves. If the tank roof is too low, the liquid will slam into the roof, causing structural damage or overflow. The code mandates a minimum freeboard based on the site's (S_D1) and tank radius.
The standard dictates when a tank must be anchored to its foundation versus when it can sit unanchored (gravity base). It defines the overturning moment ($M$) and base shear ($V$) specifically for circular and rectangular tanks. The original ACI 350
However, some research has identified limitations. A 2023 study in the Journal of Numerical Methods in Civil Engineering found that expressions presented in ACI 350.3-06 should be revised when calculating sloshing height in a rectangular tank. Additionally, the frequency content of the input ground motion significantly affects the contained liquid responses for both hydrodynamic pressure and sloshing height.
This article is for informational purposes only. Always refer to the official standards and consult with a qualified structural engineer for specific design applications. The American Concrete Institute periodically issues errata and new editions; verify the current status of any standard before use. The total base shear is calculated by combining
The design philosophy of ACI 350.3-06 is based on the concept of ductility, which allows structures to absorb seismic energy through inelastic deformations. The standard encourages designers to use a performance-based approach, where the structure is designed to achieve a specific level of performance under different levels of seismic hazard.
: Guidelines for construction techniques, including formwork, placement of reinforcement, concrete placement, and curing.
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: