Robin Atkinson of HAC engineers has over 30 years of experience in building concrete tanks, reinforced concrete tanks and water retaining structures. Concrete tanks and reinforced concrete tanks aid water treatment. Some examples of concrete tanks and water retaining structures can be seen on the water treatment page.

concrete tanks and reinforced concrete tank

HAC are specialists in the design of water retaining reinforced concrete tanks.

The design of these structures is led by Robin Atkinson who has over 30 years experience designing concrete tanks. Previously, these tanks were designed by hand as separate panels using tables from recognised books but these designs could never accurately reproduce the behaviour of the combined structure. The use of computer based finite element and grillage techniques allows these structures to be designed with greater accuracy and hence economy.

The analysis produces many results which are a combination of bending and axial forces and it has always been a challenge to calculate the crack widths to BS8007 for these combined forces. HAC have distilled all of the key service and ultimate design requirement including thermal, shear, cover requirements, creep, bending and axial and torsion into a concise Excel based spreadsheet. This verifies the proposed reinforcement on a column by column basis thus allowing the requirements for a complete section of a tank to be displayed concisely.

The design of this spreadsheet exposed gaps in BS8007 which Robin Atkinson and Erhard Kruger resolved in their joint paper published in the Structural Engineer Magazine. (see below) The non graphical output method required the solution of a cubic equation using complex number theory. The results have been meticulously checked against published examples and against Erhard Kruger’s similar work.

The layout and usability of this spreadsheet has ensured a uniformity of design procedure and output for tanks and indeed any structural member including beams and columns. It has been adapted to suit the Eurocode EC2 for both ultimate and service designs. It also allows an EC2 shear or punching shear design to be checked. HAC have been running tests comparing EC2 against BS8110 and BS8007 and have found that EC2 requires more reinforcement to resist cracking when there are high tension forces.

Robin Atkinson has published a paper on the subject in Water and Waste Treatment magazine (see below) and has delivered a talk to the IStructE Thames Valley and North Thames branches (see below). He assisted in the early development of QSE and is in regular contact with several of the suppliers of finite element packages and has advised on the pitfalls of uncontrolled use of this software. A static example of the spreadsheet is included below which includes many charts. It allows engineers to see how the N & M interaction curve relates to the stress / strain diagrams.

A web based demonstration trial version is now downloadable via the prompt below. The charts are not as crisp as they are in the original Excel version but they are interactive and demonstrate how the program works. The method and interactivity of the charts can also be seen on the BSCharts and EC2Charts videos. The fully functional original Excel program is now available for trial and purchase which displays 9 designs and 6 charts per page. Please visit the HAC Software page. Feedback and comments on the program are welcome.

BS Charts Video          EC2 Charts Video        

Article in Water and Waste Treatment Magazine - March 2009
Tank Design Standards Change[PDF Download]

Article in Water and Waste Treatment Magazine - June 1997
The Design of Concrete Tanks [PDF Download]

Talk at the Institution of Structural Engineers - September 2003
A Modern Approach to the Design of Concrete Tanks [PDF Download]

Joint Article with Erhard Kruger in Structural Engineer Magazine – May 2005
Improved crack width calculation method to BS8007 for combined flexure and direct tension
[PDF Download]

Reinforcement Calculation Spreadsheet
Notation and Diagrams and Output [PDF Download]

Clarifier GA [PDF Download]

Clarifier RC [PDF Download]

Tank Complex RC [PDF Download]

Aerator GA [PDF Download]


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