Seismic Design of Storage Tanks: November 2009

Recommendations of a NZSEE Study Group on Seismic Design of Storage Tanks

An updated revision of the 1986 “Red Book” has been released by the NZSEE Study Group and is available to interested uses.

The Recommendation for the Seismic Design of Storage Tanks provides guidance on the particular dynamic load effects during an earthquake of liquids stored in various forms of containment systems, or tanks. Structural analysis and design criteria for tanks constructed from steel, reinforced concrete and other materials are covered by the recommendations. Tank foundation investigation, evaluation, analysis and details are considered. A wide range of issues to do with the design detail are reviewed and covered by commentary, and the document contains design charts and design examples.

The recommendations were first published in 1986 and have been widely used in New Zealand as well as acknowledged internationally. Since 1986 there have been substantial changes to the regulatory environment and applicable standards in New Zealand. Therefore, to meet current requirements the principal changes in this revised document are:

• Seismic load is derived from the current national standard for derivation of seismic loads for buildings in New Zealand, NZS 1170.5.
• A procedure is presented to allow assessment of an appropriate return period factor, Ru.
• A correction factor based on the ductility and damping applicable to tank behaviour is applied.
• Some limited ductility is permitted in steel tanks on grade. This generally reduces the load demands from those given previously.
• The document is presented in a form that can be interfaced with other international design codes.

The document was put out for public comment by the New Zealand  Environmental Protection Authority to determine if the document can be used for the design of tanks for the storage of hazardous substances. The comments are to be reviewed by the NZSEE Management and Project Committees. When approval is given the Seismic Design of Storage Tanks will be re-issued.

Please note that this document is not a “Standard” but a design guide. Designers should assess for themselves as to if the guidance provided by the NZSEE document “Seismic Design of Storage Tanks – November 2009” is appropriate for the structure they propose to design and construct.

An addendum has not yet been fully developed, but notes on identified errors can be downloaded below.

Seismic Design of Storage Tanks – November 2009

Seismic Design of Storage Tanks – Notes